2011 - JAMB Physics Past Questions and Answers - page 2
11
A machine is used to lift a load of 20 N through a height of 10 m. if the efficiency of the machine is 40%, how much work is done?
A
80 J
B
500 J
C
300 J
D
120 J
12
I. Density of the liquid.
II. Depth below the surface of the liquid.
III. Surface area of the liquid.
In which of the statement above will pressure be dependent?
A
I and II only.
B
II and III only.
C
I, II and III only.
D
I and III only.
13
Which of the following could be effectively used to reduce friction?
A
kerosene
B
grease
C
water
D
petrol
14
Which of the following types of waves needs a medium for propagation?
A
sound waves
B
light waves
C
radio waves
D
x - rays
15
Which of the following electromagnetic waves has the highest frequency?
A
utra - violet rays
B
radio waves
C
x - rays
D
infrared - rays
16
A perfect emitter or absorber of radiant energy is a
A
conductor
B
black body
C
white body
D
red body
17
The ground is always cold at night because the
A
atmosphere absorbs the sun's energy at night
B
earth radiates heat to the atmosphere at night
C
sun no longer shine at night
D
atmosphere reflects the sun's energy at night
18
A cannon is fired from town X,after how long is the sound heard at a town Y 4.95 km away?
[velocity of sound in the air = 330 ms-1]
[velocity of sound in the air = 330 ms-1]
A
30 s
B
10 s
C
10 s
D
15 s
19
The phenomenon that shows that increase in pressure lowers the melting point can be observed in
A
sublimation
B
condensation
C
coagulation
D
regelation
20
A block of aluminum is heated electrically by a 30 w heater if the temperature rises by 10°c in 5 minutes, the heat capacity of the aluminum is
A
900 JK-1
B
90 JK-1
C
100 JK-1
D
200 JK-1
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