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

1

The derived unit of pressure can be expressed as

A

kgms

^{-2}B

kg m

^{-1}s^{-2}C

kg m

^{-2}s^{-2}D

kg m

^{-1}s^{2}**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

510cm

^{3}B

340cm

^{3}C

254cm

^{3}D

170cm

^{3}**correct option:**b

V = \(\frac{M}{D}\)

= \(\frac{3.06}{10} \times \frac{1000}{0.9} = 340\)

Users' Answers & Comments= \(\frac{3.06}{10} \times \frac{1000}{0.9} = 340\)

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 speedA

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

Users' Answers & Comments= 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 = \(\frac{1}{2} gt^2\)

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

Users' Answers & Comments\(\frac{1}{2} \times 10 \times 4^2 = 80\)