# 2012 - WAEC Physics Past Questions & Answers - page 1

1
The derived unit of pressure can be expressed as
A
kgms-2
B
kg m-1s-2
C
kg m-2s-2
D
kg m-1s2
CORRECT OPTION: b
2
The diagram above illustrates trapped air in a syringe placed in water that is gradually heated. It is observed that the piston rises as the temperature of the water rises. Which of the following statements explains this observation?
A
frequency of collision of trapped air molecules with walls of the syringe is more
B
molecules of trapped air expands more
C
speed of the trapped air molecules decreases
D
number of molecules of trapped air increases
CORRECT OPTION: b
3
Which of the following devices is used to determine the relative density of an acid?
A
manometer
B
hydrometer
C
hypsometer
D
hygrometer
CORRECT OPTION: b
4
A block of wood of density 0.6 gcm-3, weighing 3.06N in air, floats freely in a liquid of density 0.9 gcm-3. Calculate volume of the portion immersed (g = 10ms-2)
A
510cm3
B
340cm3
C
254cm3
D
170cm3
CORRECT OPTION: b
V = $$\frac{M}{D}$$

= $$\frac{3.06}{10} \times \frac{1000}{0.9} = 340$$
5
A metal ball of weight W falls through a column of glycerine of viscosity V. If the ball experiences an upthrust U and terminal velocity is attained is attained, then
A
W > U + V
B
W = U + V
C
W = U - V
D
W < U + V
CORRECT OPTION: b
6
The movement of fluid up or down a narrow tube is
A
osmosis
B
brownian motion
C
capillarity
D
diffusion
CORRECT OPTION: c
7
Which of the following substances is the most volatile at room temperature?
A
water
B
diesel
C
petrol
D
kerosine
CORRECT OPTION: c
8
a bird flies at 10ms-1 for 3s, 15ms-1 for 3s and 20 ms-1 for 4s. Calculate the bird's average speed
A
4.5 ms-1
B
15.0 ms-1
C
15.5 ms-1
D
51.7 ms-1
CORRECT OPTION: c
A.V. speed = $$\frac{3 \times 15 + 3 \times 20 + 4 \times 20}{3 + 3 + 4}$$

= 15.5 ms-1
9
The time of flight for a projectile motion is given by the expression
A
$$\frac{U sin \theta}{g}$$
B
$$\frac{U sin \theta}{2g}$$
C
$$\frac{2U sin \theta}{g}$$
D
$$\frac{U sin 2\theta}{g}$$
CORRECT OPTION: c
10
An object is dropped from the top of a tower. If it takes 4s for it to reach the ground, calculate the height of the tower.(g = 10 ms-2, ignore air resistance)
A
20m
B
40m
C
80m
D
160m
CORRECT OPTION: c
H = $$\frac{1}{2} gt^2$$

$$\frac{1}{2} \times 10 \times 4^2 = 80$$
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