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Pregunta 1 Informe
I
6 X + 6 H2 O → C6 H12 O6 + 6O2
III chlorophyll II IV
Use the diagram above to answer question that follows
The part labelled I is
Detalles de la respuesta
The part labelled I in the diagram refers to **sunlight**.
Here's a simple explanation:
The given chemical equation is a representation of **photosynthesis**, a process by which green plants, algae, and some bacteria convert light energy, typically from the sun, into chemical energy stored in glucose (C6H12O6) and release oxygen (O2) as a by-product.
In the context of the equation:
- **6CO2 (Carbon Dioxide) + 6H2O (Water) → C6H12O6 (Glucose) + 6O2 (Oxygen)**
The arrow indicates the transformation that occurs during the process. The **chlorophyll** (labelled in the diagram) indicates the presence of chlorophyll pigments in the chloroplasts of plant cells which are essential for **absorbing sunlight**.
Since **sunlight** is the source of energy that powers this transformation, it is the correct component for the part labelled I in the diagram.
Pregunta 2 Informe
Which of the following operates based on magnetic effect of electric current?
Detalles de la respuesta
The device that operates based on the magnetic effect of electric current is the Dynamo.
To explain further, let's look at the concept of the magnetic effect of electric current:
A Dynamo is a device that converts mechanical energy into electrical energy. It operates based on the phenomenon called electromagnetic induction, which occurs due to the magnetic effect of electric current. When a coil of wire within the dynamo rotates in the presence of a magnetic field, it induces an electric current in the coil. Thus, the operation of a dynamo relies on the interaction between electric current and magnetic fields.
To contrast with other options:
Pregunta 3 Informe
The process of adding impurities to a semiconductor material to increase its conductivity is
Detalles de la respuesta
The process you are referring to is called doping. In simple terms, doping is the method of intentionally introducing impurities into an extremely pure semiconductor to change its electrical properties, which increases its conductivity.
Semiconductors, like silicon or germanium, are materials that have electrical conductivity between conductors (like metals) and insulators (like glass). By adding impurities, we can control and enhance their ability to conduct electricity. These impurities are atoms of other elements that either have more or fewer electrons in their outer energy levels compared to those in the semiconductor.
When you add impurities with more electrons, it creates an n-type semiconductor because of the extra *negative* charge carriers (electrons). Conversely, adding impurities with fewer electrons makes a p-type semiconductor, as it creates 'holes' which act as positive charge carriers.
This process of doping is essential for creating various semiconductor devices, like diodes, transistors, and integrated circuits, which are foundational components in all electronic devices. Hence, doping plays a crucial role in the functionality and efficiency of electronic systems.
Pregunta 4 Informe
What is the colour of red rose under a blue light?
Detalles de la respuesta
To understand the color of a red rose under a blue light, we need to consider how we perceive color. Objects appear colored because they reflect certain wavelengths of light. A red rose appears red in white light because it reflects red wavelengths and absorbs others.
When you shine blue light on a red rose, the situation changes. A blue light primarily contains blue wavelengths. Since the red rose does not have red wavelengths to reflect anymore, and it cannot reflect blue light (as it absorbs it), the rose will appear to be the absence of any reflected wavelength visible to our eyes.
This means the rose will appear black under blue light, as black is perceived when no visible light is reflected into our eyes. Thus, the color of the red rose under a blue light is black.
Pregunta 5 Informe
Which of the following measuring instruments operates based on the heating effect of electric current?
Detalles de la respuesta
Hot wire ammeters measure current by detecting the heat produced in a wire due to the electric current flowing through it.
Pregunta 6 Informe
The gravitational force between two objects is 10N, what is the new value of the force if the distance between them is halved?
Detalles de la respuesta
The gravitational force between two objects is determined by Newton's Law of Universal Gravitation, which can be expressed by the formula:
F = G * (m1 * m2) / r²
where F is the gravitational force, G is the gravitational constant, m1 and m2 are the masses of the objects, and r is the distance between the centers of the two objects.
In this problem, it is given that the initial gravitational force is 10N. According to the formula, the gravitational force is inversely proportional to the square of the distance between the two objects.
So, if the distance between the objects is halved (i.e., r becomes r/2), then the new gravitational force F' can be calculated based on the relationship:
F' = G * (m1 * m2) / (r/2)² = G * (m1 * m2) / (r²/4) = 4 * (G * m1 * m2 / r²) = 4 * F
Since the initial force F was 10N, the new force F' when the distance is halved is:
F' = 4 * 10 = 40N
Thus, the new value of the gravitational force is 40N.
Pregunta 7 Informe
When a bus is accelerating, it must be
Detalles de la respuesta
When a bus is accelerating, it is primarily changing its velocity. This is because velocity is a vector quantity, which means it includes both the speed and the direction of the object's movement. Acceleration refers to any change in this velocity. Therefore, the bus could be increasing its speed, decreasing its speed (which is also known as deceleration), or changing its direction. All these aspects involve a change in velocity.
Let's break it down further:
Changing its Speed: If the bus is speeding up or slowing down, it results in a change in the magnitude of its velocity, contributing to acceleration.
Changing its Direction: Even if the bus maintains a constant speed, if it changes direction (like taking a turn), its velocity is altered because direction is a part of velocity. This results in acceleration.
Changing its Position: While a change in position happens during acceleration, it is not the defining feature of acceleration. An object can change its position even if it is moving with constant velocity and not accelerating.
So, the key component here for acceleration is the change in velocity, which encompasses changes in speed, direction, or both.
Pregunta 8 Informe
The value of R in the above circuit to make the galvanometer measure 2A is
Detalles de la respuesta
Given: Ig = 50mA = 0.05A, I to be measured = 2A, r = 2Ω , Is = I - Ig = 2 - 0.05 = 1.95A
Shunt(R) = IgIs x r
R = 0.051.95 x 10 = 0.2564Ω
Pregunta 9 Informe
Using the circuit above, at resonance
Detalles de la respuesta
To understand the concept of resonance in an electrical circuit, it is crucial to know that resonance occurs when the inductive reactance and capacitive reactance are equal in magnitude. This typically happens in a series RLC (Resistor, Inductor, Capacitor) circuit. At resonance, the impedance of the circuit is purely resistive, meaning the circuit behaves as if it only contains a resistor. As a result, the voltages across the inductor and capacitor can be compared at resonance.
In this particular situation, the voltage across the inductor (VL) and the voltage across the capacitor (VC) are of interest due to their roles in resonance:
Thus, the correct expression of interest in relation to resonance is VL = VC, which indicates that the voltage across the inductor is equal in magnitude but opposite in phase to the voltage across the capacitor.
Pregunta 10 Informe
The dimension of young's modulus,E is given by
Detalles de la respuesta
Young's modulus, denoted by E, is a measure of the stiffness of a solid material. It is defined as the ratio of stress to strain in a material that is behaving elastically. Stress is the force applied per unit area, and strain is the deformation experienced by the material in response to the applied stress.
Let's break down the dimensions for Young's modulus:
Stress: Stress is defined as force per unit area. Thus, the dimension of stress can be expressed as:
Stress = Force / Area
The dimension of force is given by mass × acceleration, i.e., Force = MLT-2 (where M is mass, L is length, and T is time).
The dimension of area is length × length = L2.
Therefore, the dimension of stress is:
Stress = (MLT-2) / (L2) = ML-1T-2
Strain: Strain is the ratio of the change in length to the original length and is dimensionless because it is a ratio of two lengths.
Thus, the dimension of strain is simply 1 (dimensionless).
Since Young's modulus is the ratio of stress to strain, its dimension is the same as that of stress. Therefore, the dimension of Young’s modulus E is:
ML-1T-2
Pregunta 11 Informe
The diaphragm in the camera is similar to what part of the eyes?
Detalles de la respuesta
The diaphragm in a camera is similar to the iris in the human eye.
Here's a simple explanation:
In summary, the iris acts like a natural diaphragm, regulating the light that passes through the eye, much like the diaphragm does in a camera.
Pregunta 12 Informe
The power of a convex lens of focal length 20cm is
Detalles de la respuesta
The power of a lens is a measure of its ability to converge or diverge light. It is defined as the reciprocal (or inverse) of the focal length of the lens. The formula for calculating the power (P) of a lens in diopters (D) is given by:
P = 1/f
where:
In this case, the focal length given is 20 cm. To apply the formula, we first need to convert this focal length into meters because the diopter is the reciprocal of the focal length in meters:
f = 20 cm = 0.20 m
Now, substitute the focal length in meters into the formula for power:
P = 1 / 0.20
P = 5.00 D
Thus, the power of the convex lens is 5.00 diopters. This indicates that the lens is capable of converging light at a distance of 5.00 meters.
Pregunta 13 Informe
The acceleration of a free fall due to gravity is not a constant everywhere on the Earth's surface because
Detalles de la respuesta
The elliptical shape of the Earth: The Earth is not a perfect sphere; it is slightly flattened at the poles and bulging at the equator. This shape causes variations in gravitational acceleration.
Pregunta 14 Informe
The property by which a material returns to its original shape after the removal of force is called
Detalles de la respuesta
The property by which a material returns to its original shape after the removal of force is called Elasticity.
Let's break it down:
Elasticity: This is a property of a material that allows it to return to its original shape or size after the force that caused deformation is removed. Think of a rubber band—you can stretch it, but once you let it go, it snaps back to its initial shape.
Ductility: This property refers to a material's ability to be stretched into a wire. For example, materials like copper are ductile because they can be drawn into thin wires without breaking.
Malleability: This is a material's ability to withstand deformation under compressive stress. It is the property that allows metals to be hammered or rolled into thin sheets. Gold is a good example of a malleable metal.
Plasticity: This property describes the material's ability to undergo permanent deformation without breaking. When a plastic region is reached, the material will not return to its original shape after the removal of force.
Therefore, when we speak of a material returning to its original shape after the removal of force, we are specifically referring to Elasticity.
Pregunta 15 Informe
Two tuning forks of frequencies 6Hz and 4Hz respectively are sounded together. The beat frequency is
Detalles de la respuesta
When two sound waves of slightly different frequencies are sounded together, they interfere with each other in such a way that the intensity of the sound alternates between loud and soft. This phenomenon is known as "beats". The number of beats heard per second is called the "beat frequency".
The beat frequency can be calculated by subtracting the frequency of one wave from the frequency of the other. Mathematically, it is represented as:
Beat Frequency (fbeat) = | f1 - f2 |
Where:
In this case:
Using the formula:
fbeat = | 6Hz - 4Hz | = | 2Hz | = 2Hz
Therefore, the beat frequency is 2Hz. This means that you would hear 2 beats per second when the tuning forks of frequencies 6Hz and 4Hz are sounded together.
Pregunta 16 Informe
The force of attraction between molecules of the same substance is
Detalles de la respuesta
The force of attraction between molecules of the same substance is called cohesion.
To understand this simply:
Cohesion refers to the attractive forces acting between similar molecules. For example, water molecules attract each other due to hydrogen bonding, which is a strong intermolecular force.
Let's break down some important concepts:
In summary, **cohesion** is the force that keeps the molecules of the same substance, like water, attracting each other.
Pregunta 17 Informe
Using the diagram above, the effective force pushing it forward at an angle 60º is
Detalles de la respuesta
To determine the effective force pushing the object forward at an angle of 60º, we need to resolve the given force into its components. Specifically, we are interested in the horizontal component of the force, as this is the part that effectively pushes the object forward.
The general formula to calculate the horizontal component of a force (Fx) when the force is applied at an angle (θ) is:
Fx = F * cos(θ)
Where:
Assuming the magnitude of the force applied (F) is 50N, then the effective forward force can be calculated as follows:
Fx = 50N * cos(60º)
Using the trigonometric value:
cos(60º) = 0.5
Therefore:
Fx = 50N * 0.5
Fx = 25N
Hence, the effective force pushing it forward at an angle of 60º is 25.00N. Therefore, the correct answer is 25.00N.
Pregunta 18 Informe
An electron falls from an energy level of -5.44eV to another energy level, E. If the emitted photon is of wavelength 5.68 x 10−6 m, calculate the energy change. [ Plank's constant = 6.63 x 10−34 Js, emitted radiation speed = 3.0 x 108 ms−1 ]
Detalles de la respuesta
To find the energy change when an electron falls from one energy level to another, we need to calculate the energy of the emitted photon. This energy can be found using the formula:
E = hν or E = hc/λ
where:
Substitute these values into the equation:
E = (6.63 x 10-34 Js) * (3.0 x 108 ms-1) / (5.68 x 10-6 m)
First, calculate the numerator:
(6.63 x 10-34) * (3.0 x 108) = 1.989 x 10-25 J·m
Then, divide by the wavelength:
E = 1.989 x 10-25 J·m / 5.68 x 10-6 m = 3.5 x 10-20 J
Therefore, the energy change when the electron falls is approximately 3.5 x 10-20 J.
Checking the options provided, the closest value is 3.49 x 10-20 J.
Pregunta 19 Informe
In the diagram above, the galvanometer is converted to
Detalles de la respuesta
To determine what the galvanometer is converted to in the described scenario, let’s first understand how a galvanometer can be transformed into different measuring devices:
1. Galvanometer to Voltmeter: To convert a galvanometer into a voltmeter, a high resistance (known as a multiplier) is connected in series with the galvanometer. This high resistance ensures that the voltmeter can measure a wide range of voltages without drawing significant current from the circuit.
2. Galvanometer to Ammeter: To convert a galvanometer into an ammeter, a low resistance (called a shunt) is connected in parallel with the galvanometer. This allows the majority of the current to pass through the shunt, enabling the ammeter to measure high currents without damaging the galvanometer.
Since the problem statement does not specify any additional details, a general observation is that a galvanometer is commonly converted into an ammeter using a shunt, especially in basic electrical circuits where current measurement is necessary. Therefore, from the options provided, **the galvanometer is most likely converted to an ammeter**.
**In summary**, if a low resistance is added in parallel with the galvanometer, it becomes an ammeter, while adding a high resistance in series would convert it into a voltmeter. Since the context commonly involves conversion for current measurement, the provided diagram likely represents a galvanometer converted into an ammeter.
Pregunta 20 Informe
The part of the inner ear that is responsible for hearing is
Detalles de la respuesta
The part of the inner ear that is responsible for hearing is the cochlea.
The inner ear is a complex structure, and each of its components serves different functions. Let me break it down further:
Thus, the cochlea is the crucial component of the inner ear responsible for converting sound vibrations into nerve signals, making it central to the process of hearing.
Pregunta 21 Informe
One of these is not the use of an electroscope
Detalles de la respuesta
Measuring ionization current in air:
This is typically not a function of an electroscope. While it can detect charge, it does not measure ionization currents, which require specialized equipment like an ionization chamber.
Pregunta 22 Informe
A mass of gas at 40mmHg is heated from 298k to 348k at constant volume. Cal the pressure exerted by the gas.
Detalles de la respuesta
To determine the new pressure exerted by the gas when it is heated, we'll apply **Gay-Lussac's Law**. This law states that at constant volume, the pressure of a given amount of gas is directly proportional to its absolute temperature. Mathematically, it can be expressed as:
P1/T1 = P2/T2
Where:
By rearranging the formula to solve for the final pressure (P2), we get:
P2 = P1 * (T2/T1)
Now, insert the given values into the equation:
P2 = 40 mmHg * (348 K / 298 K)
Perform the calculations:
P2 = 40 mmHg * (348 / 298)
P2 = 40 mmHg * 1.1678
P2 = 46.71 mmHg
So, the new pressure exerted by the gas when it is heated from 298 K to 348 K at constant volume is 46.71 mmHg.
Pregunta 23 Informe
A wheelbarrow inclined at 60º to the horizontal is pushed with a force of 150N. What is the horizontal component of the applied force
Detalles de la respuesta
When you push a wheelbarrow inclined at an angle to the horizontal, the applied force can be divided into two components: a **horizontal component** and a **vertical component**. To find the horizontal component of the force, you need to use the concept of resolving vectors.
The force of 150N is acting at an angle of 60º to the horizontal. The horizontal component of this force can be calculated using the cosine of the angle. The formula to determine the horizontal component \( F_{\text{horizontal}} \) is given by:
Fhorizontal = Fapplied \times \cos(\theta)
Where:
Substitute the values into the formula:
Fhorizontal = 150N \times \cos(60º)
We know that \(\cos(60º)\) equals 0.5.
Therefore:
Fhorizontal = 150N \times 0.5 = 75N
Thus, the **horizontal component** of the applied force is 75N.
Pregunta 24 Informe
In electrolysis, when same quantity of electricity is passed through different electrolytes, mass of substances deposited is proportional to
Detalles de la respuesta
In electrolysis, when the same quantity of electricity is passed through different electrolytes, the mass of substances deposited is proportional to their chemical equivalent. The reason for this lies in Faraday's laws of electrolysis. Faraday's second law states that the amounts of different substances deposited or liberated by the same quantity of electricity are proportional to their chemical equivalents.
Chemical equivalent refers to a measure of a substance's ability to react or be deposited during electrolysis, and it is calculated as the molar mass divided by valency (n). This is why it is sometimes also referred to as equivalent weight.
In essence, for a given charge (equal number of electrons or electricity), a substance with a lower chemical equivalent will deposit more mass because it requires fewer electrons to undergo the chemical change.
Pregunta 25 Informe
The tangential force acting on an object that opposes it from sliding freely on the adjacent surface is called
Detalles de la respuesta
The tangential force acting on an object that opposes it from sliding freely on the adjacent surface is called the friction force.
Let me explain each of the options to clarify why friction force is the correct answer:
In summary, friction force is the force that acts to oppose sliding between surfaces in contact and acts tangentially, making it the correct answer.
Pregunta 26 Informe
Use the diagram above to answer the question that follows
The diagram above is
Detalles de la respuesta
The diagram in the image represents the urinary system, as indicated by the correct answer. The urinary system includes the kidneys, ureters, bladder, and urethra, which are responsible for filtering blood and excreting waste in the form of urine.
Kidneys – Filter waste and excess fluids from the blood to form urine.
Ureters – Tubes that carry urine from the kidneys to the bladder.
Urinary Bladder – Stores urine before it is expelled from the body.
Urethra – A tube that allows urine to exit the body.
This system plays a crucial role in maintaining the body's fluid balance and removing waste products.
Pregunta 27 Informe
The value of R required to make the galvanometer measure voltage up to 40V in the diagram above
Detalles de la respuesta
In a galvanometer setup intended to measure voltages, you often encounter a configuration known as a voltmeter, where a resistor is added in series with the galvanometer to increase its range of measurement.
The basic principle is that the total resistance of the voltmeter (comprising the galvanometer's resistance and the additional series resistor) allows it to handle a higher voltage by limiting the current that flows through the galvanometer. The maximum voltage (V) that can be measured by the galvanometer is determined by Ohm's Law: V = I * R,
Where:
Assuming the galvanometer has a known internal resistance (G) and a known full-scale current (I_fullscale), the resistance R required in series can be calculated via the formula:
R = (V / I_fullscale) - G
For this solution, you need either the values of G and I_fullscale or their product (G * I_fullscale). Without those exact specifications provided, it would be imprudent to give an exact numeric answer.
However, if this is a typical example and you have a typical galvanometer with a full-scale current of 50 μA and an internal resistance of 500 Ω, you can compute:
R = (40 / 50 x 10^-6) - 500 = 2000 - 500 = 1500 Ω
Therefore, you would need an additional R = 1990 Ω - 1500 Ω = 490 Ω, meaning the closest possible practical value from your choices is 1990 Ω (including the internal resistance).
If the specific parameters of the galvanometer differ, adjust the calculation accordingly, but the general process is as laid out here.
Pregunta 28 Informe
If a charge ion goes through a combined electric field E and magnetic field B, the resultant emergent velocity of the ion is
Detalles de la respuesta
The resultant emergent velocity of a charged ion moving through combined electric and magnetic fields can be derived from the condition where the electric force equals the magnetic force. This gives us the formula for the velocity v:
q E = qvB
v = EB (q will cancel out)
NOTE: When both fields are present, for the ion to move without deflection, the electric force must equal the magnetic force.
Pregunta 29 Informe
At a pressure of 105 Nm−2 , a gas has a volume of 20m3 . Calculate the volume at 4 x 105 Nm−2 at constant temperature.
Detalles de la respuesta
In order to solve this problem, we can apply **Boyle's Law**, which states that the **pressure** and **volume** of a gas are inversely proportional at a constant temperature. Mathematically, this is expressed as:
P1V1 = P2V2
Where:
Rearranging the formula to solve for V2:
V2 = (P1V1) / P2
Substituting the given values:
V2 = (105 Nm-2 x 20 m3) / (4 x 105 Nm-2)
By calculating:
V2 = (2100 m3) / 4 x 105
V2 = 5 m3
Therefore, at a pressure of 4 x 105 Nm-2, the volume of the gas is 5 m3.
Pregunta 30 Informe
A blacksmith heated a metal whose cubic expansivity is 3.9 x 10−6 K−1 . Calculate the area expansivity.
Detalles de la respuesta
To find the area expansivity of a metal when given its cubic expansivity, you should understand the relationship between linear, area, and cubic expansivity.
Cubic expansivity (\( \beta \)) is defined as the fractional change in volume per change in temperature, and is given by the formula:
\[ \Delta V = \beta V \Delta T \]
Area expansivity (\( \alpha_{A} \)) corresponds to the fractional change in area per change in temperature and can be derived from the linear expansivity (\( \alpha \)). The relationship between these expansivities is as follows:
\[ \text{Area Expansivity (\( \alpha_{A} \))} = 2 \times \text{Linear Expansivity (\( \alpha \))} \]
The cubic expansivity (\( \beta \)) is related to the linear expansivity by:
\[ \text{Cubic Expansivity (\( \beta \))} = 3 \times \text{Linear Expansivity (\( \alpha \))} \]
Thus, based on these relationships, we can express the area expansivity in terms of the cubic expansivity:
\(\text{Area Expansivity (\( \alpha_{A} \))} = \frac{2}{3} \times \text{Cubic Expansivity (\( \beta \))}
Given that the cubic expansivity \( \beta \) is \( 3.9 \times 10^{-6} \, \text{K}^{-1} \):
The area expansivity can be calculated as follows:
\[ \text{Area Expansivity (\( \alpha_{A} \))} = \frac{2}{3} \times 3.9 \times 10^{-6} \, \text{K}^{-1} = 2.6 \times 10^{-6} \, \text{K}^{-1} \]
Therefore, the **correct answer** is **2.6 x 10^{-6} K^{-1}**.
Pregunta 31 Informe
Use the diagram above to answer the question that follows
The organism belongs to kingdom
Detalles de la respuesta
The diagram is that of the virus. Viruses are obligate parasites, meaning they can't produce their own energy or proteins. They enter the host cell and use the cell's machinery to make their own nucleic acids and proteins. Viruses also use the host cell's lipids and sugar chains to create their membranes and glycoproteins. This parasitic replication can severely damage the host cell, which can lead to disease or cell death. They usually enter your body through your mucous membranes. These include your eyes, nose, mouth, penis, vagina and anus.
Viruses are a unique type of organism that are not plants, animals, or bacteria. They are often classified in their own kingdom. However, for the sake of the question, since most of their attributes and metabolic activities are more of the bacteria, we'll go with option A - Monera
Pregunta 32 Informe
In voltage measurement, the potentiometer is preferred to voltmeter because it
Detalles de la respuesta
In voltage measurement, a **potentiometer is preferred to a voltmeter** primarily because it **consumes negligible current**. Let me explain this in simpler terms:
A **voltmeter** is an instrument used to measure the potential difference (voltage) across two points in an electrical circuit. However, when a voltmeter is connected, it draws a small amount of current from the circuit to make the measurement, which can slightly alter the voltage being measured. This is particularly an issue in high-resistance circuits where even a small current draw can significantly affect the measurement.
On the other hand, a **potentiometer** is a device designed to measure voltage by comparing it with a known reference voltage without drawing current from the circuit under test. It comes into balance at a point where no current flows through it, ensuring that the measurement is not influenced by the potentiometer itself. This makes it a non-invasive method of measuring voltage, which is particularly useful for precise measurements in sensitive circuits.
Here’s a brief explanation about why the other options listed are less relevant:
Therefore, the key advantage of the potentiometer is its **ability to measure voltage without altering the circuit**, which stems from its negligible current consumption. This **ensures more accurate and reliable measurements** in many applications.
Pregunta 33 Informe
An air force jet flying with a speed of 335m/s went past an anti-aircraft gun. How far is the aircraft 5s later when the gun was fired?
Detalles de la respuesta
To solve this problem, we need to determine how far the aircraft travels in the 5 seconds after it passes the anti-aircraft gun. The problem gives us two key pieces of information:
To find the distance traveled, we use the formula for distance:
Distance = Speed × Time
Plugging in the given values:
Distance = 335 m/s × 5 s
Calculating this, we get:
Distance = 1675 meters
This means the aircraft is 1675 meters away from the point where it passed the anti-aircraft gun after 5 seconds.
Pregunta 34 Informe
Calculate the depth of a swimming pool if the apparent depth is 10cm. ( Refractive index of water = 1.33 )
Detalles de la respuesta
To calculate the real depth of a swimming pool given the apparent depth, we can use the concept of refraction of light. When light passes from one medium to a denser medium, it bends towards the normal. This bending effect causes objects submerged in water to appear closer to the surface than they actually are. The formula to relate these depths is given by:
Real Depth = Apparent Depth × Refractive Index
Given the problem:
Using the formula:
Real Depth = 10 cm × 1.33
Calculating the above:
Therefore, the depth of the swimming pool is 13.3cm.
Pregunta 35 Informe
An object is placed 25cm in front of a convex mirror has its image formed 5cm behind the mirror. what is the focal length of the convex mirror
Detalles de la respuesta
Object distance (u) = -25 cm (negative because the object is in front of the mirror)
Image distance (v) = +5 cm (positive because the image is behind the convex mirror)
Using 1f = 1u + 1v
1f = 1−25 + 15
f = 254 = 6.250cm.
Pregunta 36 Informe
The gravitational force between two objects masses 1024 kg and 1027 kg is 6.67N. Calculate the distance between them [ G = 6.6 x 10−11 Nm2 kg−2 ]
Detalles de la respuesta
To calculate the distance between two objects based on the gravitational force acting between them, we need to use the formula for gravitational force:
F = (G * m1 * m2) / r²
Where:
We need to compute r by rearranging the formula:
r² = (G * m1 * m2) / F
Therefore, the distance r is:
r = √((G * m1 * m2) / F)
Substitute the given values into the equation:
r = √((6.6 x 10-11 Nm²/kg² * 1024 kg * 1027 kg) / 6.67 N)
Calculating inside the square root:
G * m1 * m2 = 6.6 x 10-11 * 1024 * 1027 = 6.6 x 1040 Nm²
Then divide by the force:
6.6 x 1040 Nm² / 6.67 N = 0.99 x 1040 m²
Finally, calculate the square root:
r = √(0.99 x 1040)
r ≈ 1.0 x 1020 m
Therefore, the distance between the two objects is approximately 1.0 x 1020 m.
Pregunta 37 Informe
The changes of living organisms over generation is referred to as
Detalles de la respuesta
The changes of living organisms over generations are referred to as organic evolution.
Organic evolution, also known as biological evolution, is the process through which species of organisms undergo changes over time due to genetic variations and environmental factors. This leads to the development of new traits and, over long periods, may result in the emergence of new species.
Here's a simple breakdown of the concept:
This process is a key concept in biology and is fundamental to understanding the diversity of life on Earth. Organic evolution is distinct from other kinds of evolution mentioned, as it specifically deals with biological organisms.
Pregunta 38 Informe
An ideal transformer has
Detalles de la respuesta
An ideal transformer is a hypothetical concept used in electrical engineering to simplify the analysis of real transformers. In an ideal transformer, several assumptions are made to avoid losses and inefficiencies. Here's what an ideal transformer has:
No flux leakage: In an ideal transformer, it is assumed that all the magnetic flux generated in the primary coil is perfectly linked with the secondary coil. This means there is no flux leakage. This assumption ensures maximum efficiency, as all the energy is transferred from the primary to the secondary coil without losses.
Let's briefly discuss the other concepts to understand why they don't pertain to an ideal transformer:
Maximum primary resistance: In an ideal transformer, the resistance of the windings is assumed to be zero. If the primary has maximum resistance, it would result in power loss due to the resistance, contradicting the idea of an ideal transformer.
Hysteresis: This refers to the energy loss that happens in the core material due to the cyclic magnetization and demagnetization processes. An ideal transformer assumes there is no hysteresis loss, meaning the core material does not absorb any energy during these cycles.
Eddy current: These are loops of electric current induced within conductors by a changing magnetic field, which can cause significant energy loss. In an ideal transformer, it is assumed that there are no eddy currents, hence no energy loss due to this effect.
In summary, an ideal transformer is characterized by having no flux leakage, and it assumes that there are no losses due to resistance, hysteresis, or eddy currents. This makes the ideal transformer a perfect, lossless device for the purposes of theoretical analysis.
Pregunta 39 Informe
Under which conditions is work done
Detalles de la respuesta
In physics, the concept of work is defined as the process of energy transfer that occurs when a force makes an object move. The conditions for work to be done are:
Now, let's evaluate each scenario:
A man supports a heavy load on his head with hands: In this case, although the man is applying a force upward to support the load, the load does not move in the direction of the force he is exerting (upward). Hence, no work is done.
A woman holds a pot of water: Similar to the first scenario, the woman applies an upward force to hold the pot. However, the pot remains stationary, and there is no movement in the direction of the force. Thus, no work is done.
A boy climbs onto a table: Here, as the boy climbs, he applies a force to move himself upward onto the table. The movement is in the direction of the upward force he is applying. Therefore, work is done.
A man pushes against a stationary petrol tanker: In this scenario, although the man is applying a force to the tanker, it does not move. Because there is no movement in the direction of the force, no work is done.
Pregunta 40 Informe
One main feature of trees in the savanna habitat is the possession of
Detalles de la respuesta
The main feature of trees in the savanna habitat is the possession of thick, corky bark. The savanna is characterized by a distinct wet and dry season. During the dry season, fires are common as dry grasses and leaves become highly flammable. To adapt to this environmental condition, many trees in the savanna have developed a thick, corky bark which helps protect them against these frequent fires. This bark acts as an insulator, shielding the vital inner tissues of the tree from the heat of the flames. Additionally, this adaptation helps the trees retain moisture, which is crucial during the arid months when water is scarce.
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