2013 - JAMB Physics Past Questions and Answers - page 1

1
When a brick is taken from the earth's surface to the moon, its mass
A
remains constant
B
reduces
C
increases
D
becomes zero
correct option: a
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2
The resultant of two forces is 50N. If the forces are perpendicular to each other and one of them makes an angle 0f 30o with the resultant, find its magnitude.
A
100.0N
B
57.7N
C
43.3N
D
25.0N
correct option: c
F = 50Cos30o = 43.3
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3
The pair of physical quantities that are scalar only are ?
A
volume and area
B
moment and momentum
C
length and displacement
D
Impulse and time
correct option: a
This is because volume and the area have only magnitude but no direction
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4
A simple pendulum of length 0.4m has a period of 2s. What is the period a similar pendulum of length 0.8m at the same place?
A
8s
B
4s
C
2\(\sqrt{2}s\)
D
\(\sqrt{2}s\)
correct option: c
T2 = \(\sqrt{\frac{L^2 \times T_1^2}{L_1}}\)

= \(\sqrt{\frac{0.8 \times 2^2}{0.4}}\)

= 2\(\sqrt{2}s\)
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5
A train with an initial velocity of 20ms-1 is subjected to a uniform deceleration of 2m-2. The time required to bring the train to a complete halt is?
A
5s
B
10s
C
20s
D
40s
correct option: b
t = \(\frac{v - u}{a}\) = \(\frac{0 - 20}{-2}\) = 10s
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6
Calculate the apparent weight loss of a man weighing 70kg in an elevator moving downwards with an acceleration of 1.5ms-2.

[g = 10ms-2]
A
686N
B
595N
C
581N
D
105N
correct option: d
Wt loss = mg - m (g - a)

= 70 x 10 - 70 (10 - 1.5) = 105N
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7
A piece of cork floats in a liquid. What fraction of its volume will be immersed in the liquid?

[Density of the cork = 0.25 x 103kgm-3, Density of the liquid = 1.25 x 103kgm-3]
A
0.8
B
0.5
C
0.2
D
0.1
correct option: c
\(\frac{0.25 \times 10^3} {1.25 \times 10^3}\) = 0.2
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8
An object is moving with a velocity of 5m-1. At what height must a similar body be situated to have a potential energy equal in value with kinetic energy of the moving body?
A
25.0m
B
20.0m
C
1.3m
D
1.0m
correct option: c
P.E = K.E

Therefore, h = \(\frac{v^2}{2g} = \frac{5^2}{2 \times 10}\)

= 1.25

Approx 1.3 (C)
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9
If a pump is capable of lifting 5000kg of water through a vertical height of 60m in 15 min, the power of the pump is
A
2.2.5 x 10 5js-1
B
2.5 x 104js-1
C
3.3 x 103js-1
D
3.3 x 102js-1
correct option: c
P = \(\frac{mgh}{t}\)

P = \(\frac{5000 \times 10 \times 60}{(15 \times 60)s}\)

P = 3333.3333

P = 3.3 x 103js-1
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10
The coefficient of friction between two perfectly smooth surface is
A
infinity
B
one
C
half
D
zero
correct option: d
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