JAMB UTME - Physics - 1986

A 1000kg elevator is descending vertically with an acceleration of 1.0ms-2, if the acceleration due to gravity is 10ms-2, the tension in the suspending cable is

Antwoorddetails

The elevator is descending so the weight acts in line with the acceleration which is downwards. So according to Newton's law,
mg(weight) -R (tension/reaction) = ma

If the inclination at Ibadan is 7oS, this means that

Antwoorddetails

The sign of the change on a charged glass rod may be determined with

Antwoorddetails

Which of the following is most strongly deflected by magnetic field?

Antwoorddetails

In which of the following arrangements is the wavelength in an increasing order?

Antwoorddetails

The vibration of an air column produces the sound in the

Antwoorddetails

A man clapping his hands at regular intervals observes that the echo of a clap coincides with the next clap. If the reflecting cliff is 160m away and the speed of sound is 320ms-1, what is the frequency of the clapping?

Antwoorddetails

Total distance = 2 x 160 = 320cm

Total time = $\frac{320}{320}$ = 1s

F = $\frac{1}{1}$ = $\frac{1}{1}$

= 1Hz

If the refractive index of glass is 1.5, what is the critical angle at the air-glass interface?

Antwoorddetails

sin ic $\frac{1}{n}$ = $\frac{1}{1?5}$

i = sin-1$\frac{1}{1?5}$

= sin-1$\frac{10}{15}$

= sin-1$\frac{2}{3}$

Which of the following is NOT a part of a d.c. electric motor?

Antwoorddetails

Which of the following is in a neutral equilibrium?

Antwoorddetails

A constant force of magnitude F acts on an object of mass 0.04kg initially at rest at a point O. if the speed of the object when it has moved 50m from O is 500ms-1, what is the value of F?

Antwoorddetails

F = ma and V2 = U2 + 2aX

F = m$\frac{(V^2-U^2)}{2X}$

= 0.04$\frac{({500}^2-0^2)}{2\times 50}$

F = 100N

The expansion of solids can be considered a disadvantage in the

Antwoorddetails

When a box of mass 45kg, is given an initial speed of 5ms-1 it slides along a horizontal floor a distance of 3m before coming to a rest. what is the coefficient of kinetic friction between the box and the floor? (G = 10ms-2)

Antwoorddetails

The specific latent heat of fusion of lead is the amount of heat required to

Antwoorddetails

A rectangular tank contains water to a depth of 2m, if the base is 4m x 3m, calculate the force on the base (Density of water = 103kgm-3, g = 10ms-2)

Antwoorddetails

Volume = 2 x 4 x 3 = 24m3

mass = V x D = 24 x 103

F = mg

= 24 x 103 x 10

= 24 x 104

In fig 9 the value of R is

Antwoorddetails

If the fig above E is an accumulator with negligible internal resistance. and the EMF 9.0V, The the total current is

Antwoorddetails

Which of the following assumptions is made in a simple pendulum experiment? the

Antwoorddetails

When two objects P and Q are supplied with the same quantity of heat, the temperature change in P is observed to be twice that of Q. The ratio of the specific heat capacity of P to Q is

Antwoorddetails

$\theta$p = 2$\theta$q

mq = 2mp

Cp X mp X $\theta$p = Cq x mq x $\theta$q

$\frac{C_p{m}_q\theta q}{C_q{m}_p\theta q}$ = $\frac{\theta q\times 2mp}{2\theta qmp}$

$\frac{C_p}{Cq}$ = $\frac{2}{2}$

In fig 6, a ray of light in air strikes a glass plate at an angle of incidence 60 degrees, the reflected ray is observed to be perpendicular to the refracted ray, what is the refractive index of the glass

Antwoorddetails

Which of the following represents the correct precision if the length of a piece of wire is measured with a meter rule?

Antwoorddetails

Two objects, one having three times the mass of the other, are dropped at the same time from a tall building. When they are above the ground, the two objects will have the same

Antwoorddetails

Which of the following is a derived unit?

Antwoorddetails

Force is a derived quantity, it's unit is a derived unit

Which of the following is stored by a dry Leclanche cell?

Antwoorddetails

Which of the following is common to evaporation and boiling? They

Antwoorddetails

Which of the following is true of the loudness of sound? It

Antwoorddetails

A ball is thrown vertically into the air with an initial velocity u. What is the greatest height reached?

Antwoorddetails

Using V2 = U2 - 2gS

V = 0ms-1 at greatest height

S = $\frac{u^2}{2g}$

A lens of focal length 12.0cm forms an upright image three times the size of a real object. The distance between the object and the images is

Antwoorddetails

F = 12cm, V = 3u

F = $\frac{uv}{u+v}$

12 = $\frac{u\times 3u}{u+3v}$

u = 16cm, and v = 48cm

therefore, distance between u and v

v = 48 - 16 = 32cm

A dentist obtains a linear magnification of 4 of a hole in a tooth by placing a concave mirror at a distance, of 2.0cm from the tooth. The radius of Curvature of the mirror is

Antwoorddetails

v = 4u, if u = 2cm, v = 8cm

F = $\frac{uv}{u+v}$

= $\frac{2\times 8}{2+8}$

= 1.6cm

r = 2F

= 2 x 1.6

= 3.2cm

Which of the following is true of sounds?

Antwoorddetails

The mode of heat transfer which does not require a material medium is

Antwoorddetails

Fig 4 represents a block-and-tackle pulley system on which an effort of W newtons supports a load of 120.0N if the efficiency of the system is 40% then the value of W is

Antwoorddetails

In fig 3, three forces F1, F2, and F3 acting at O are in equilibrium. If the magnitude of F1 is 10N,and the magnitude of F2 is 5N, find the magnitude of F3

Antwoorddetails

Which of the following properties makes metals ideal for cooking utensils?

Antwoorddetails

The angle between the magnetic meridian and the geographic meridian at a locality on the earth is the

Antwoorddetails

A pencil is placed vertically between a concave mirror and its focal point. The image of the pencil in the mirror will be

Antwoorddetails

In an experiment in which molten naphthalene is allowed to cool, the cooling curve in fig 5 was obtained, the temperature ${80}^{\circ }C$ is known as

Antwoorddetails

A heavy object is suspended from a string and lowered into water so that it is completely submerged. The object appears lighter because

Antwoorddetails

A wave of frequency 10Hz forms a stationary wave pattern in a medium where the velocity is 20cms-1. The distance between adjacent nodes is

Antwoorddetails

$\lambda$ = $\frac{v}{f}$

= $\frac{20}{10}$

= 2cm ; distance between adjacent nodes

Which of the following is true of magnetism?

Antwoorddetails

A gas occupies a volume of 300cm3at a temperature of 27oC. What is its volume at 54oC, when the pressure is constant?

Antwoorddetails

$\frac{V_1}{T_1}$ = $\frac{V_2}{T_2}$

$\frac{300}{27+273}$ = $\frac{V_2}{54+273}$

V2 = 327cm3

Mercury is suitable as a barometric fluid because it

Antwoorddetails

What is the effect of the increase in the size of the hole of a pin-hole camera on the image? it

Antwoorddetails

A uniform meter rule QR is balanced on a knife edge which is 55cm from R, when a mass of 10g is hung at P as shown above, the mass of the meter rule is (Note that QP is 10cm)

Antwoorddetails

Fig 1 is a graph of force against extension for a spiral spring, the force constant of the spring is given by the

Antwoorddetails

The wavelength of ultraviolet radiation is 400nm. If the speed of light in air is 3 x 108ms-1, then the frequency of the ultraviolet radiation is

Antwoorddetails

F = $\frac{V}{\lambda }$

= $\frac{3\times {10}^8}{400\times {10}^9}$

= 75 x 1015Hz