1990 - JAMB Physics Past Questions & 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
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