# 1990 - JAMB Physics Past Questions and Answers - page 1

1
Which of the following is a fundamental unit?
A
Newton
B
Watt
C
Joule
D
Second
correct option: d
2
A car moving with a speed of 90kmh-1 was brought uniformly to rest by the application of the brakes in 10s. How far did the car travel after the brakes were applied?
A
125m
B
150m
C
250m
D
15km
correct option: c
speed = $$\frac{9 \times 10^3}{3600}$$ = 25ms-1

distance = speed x time

= 25 x 10 = 250m
3
A particle of mass M which is at rest splits up into two. If the mass and velocity of one of the particles are m and v respectively, calculate the velocity of the second particle
A
$$\frac{mv}{M}$$
B
$$\frac{Mv}{M - m}$$
C
$$\frac{mv}{M + m}$$
D
$$\frac{mv}{M - m}$$
correct option: d
(M - m)V2 = mv

V2 = $$\frac{mv}{M - m}$$
4
Which of the following statements are correct about an object in equilibrium under parallel forces? i. the total clockwise moments of the forces about any point equals the total anti-clockwise moments about the same point. ii. the total forces in one direction equals the total forces in the opposite direction. iii. the resolved components along the x-axis equals the resolved components along the y-axis.
A
i and ii only
B
i and iii only
C
ii and iii
D
i, ii, and iii only
correct option: a
5
To keep a vehicle moving at a constant speed v, requires power P, from the engine. The force provided by the engine is
A
$$\frac{p}{v}$$
B
$$\frac{1}{2}$$ v
C
pv
D
$$\frac{p}{v^2}$$ v
correct option: a
power = speed x force

force = $$\frac{power}{speed}$$
6
A stone of mass m kg is held h meters above the floor for 50s. The work done in joules over this period is
A
mh
B
mgh
C
$$\frac{mgh}{50}$$
D
O
correct option: d
work = mgh(no motion)
7
A body of mass 10kg rests on a rough inclined plane whose angle of tilt $$\theta$$ is variable. $$\theta$$ is gradually increased until the body starts to slide down the plane at 30o. The coefficient of limiting friction between the body and the plane
A
0.30
B
0.50
C
0.58
D
0.87
correct option: c
n = tan 30 = 0.58
8
An inclined plane which makes an angle of 30o with the horizontal has a velocity ratio of
A
2
B
1
C
0.866
D
0.50
correct option: a
V.R = $$\frac{1}{sin\theta}$$

= $$\frac{1}{sin30}$$

= 2
9
What is the length of liquid column in a barometer tube that would support an atmospheric pressure of 102000Nm-2 if the density of the liquid is 2600kgm-3? [g = 10ms-2]
A
0.75m
B
0.76m
C
3.92m
D
39.23m
correct option: c
pressure = g x density x height

102000 = 10 x 2600 x height

height = 3.92m
10
40m3 of liquid is mixed with 60m3 of another liquid Q. If the density of P and Q are 1.00kgm-3 and 1.6kgm-3 respectively, what is the density of the mixture?
A
0.05kgm-3
B
1.25kgm-3
C
1.30kgm-3
D
1.36kgm-3
correct option: d
Mp = 1 x 40 = 40kg ; mQ = 1.6 x 60 = 96kg

volume of mixture = 40 + 60 = 100m3

mass of mixture = 40 + 96 = 136kg

density of mixture = $$\frac{136}{100}$$

= 1.36kgm3