# 2017 - WAEC Physics Past Questions and Answers - page 1

1

The diagram above is a micrometer screw gauge. Determine its reading.

A
2.44mm
B
2.46mm
C
2.86mm
D
2.96mm
correct option: b
2

Which of the following is the dimension for impulse?

A
MLT$$^{-1}$$
B
MLT$$^{-2}$$
C
MLT
D
ML
correct option: a

Impulse = Force $$\times$$ time

Force has the dimension $$\frac{ML}{T^{2}}$$, hence

Impulse= $$\frac{ML}{T^{2}} \times T = \frac{ML}{T}$$

3

A body accelerates uniformly from rest at 2$$ms^{-2}$$. Calculate its velocity when it has travelled a distance of 9m.

A
3.0$$ms^{-1}$$
B
4.5$$ms^{-1}$$
C
6.0$$ms^{-1}$$
D
18.0$$ms^{-1}$$
correct option: c

Given that $$u = 0ms^{-1}, a = 2ms^{-2}, s = 9m$$

We can use the equation, $$v^{2}=u^{2} +2as$$ so that we have,

$$v^{2} = 0^{2} + 2\times 2\times 9$$

$$v^{2} = 36; v= 6.0ms^{-1}$$

Note; u = Initial velocity

v = final velocity

a = acceleration

s = distance covered

4

Which of the following statements about matter is not correct?

A
Molecules of solids move more freely than molecules of liquids and gases
B
Molecules of solids are more closely packed than those of liquids
C
Energy is required to break the intermolecular forces of attraction between molecules
D
Molecules of liquids move about within the liquid and they are in constant motion
correct option: a

All other properties of the different states of matter holds except that the molecules of solids don't move freely due to the fact that the particles in the solids are closely packed so it inhibits free motion.

5

A ball is projected horizontally from the top of a tower. Neglecting air resistance, which of the following statements about its motion is/are correct?

I. Vertical acceleration on the ball decreases as it falls

II. The vertical force on the ball remains constant

III. The vertical speed of the ball increases as it falls

A
I only
B
II only
C
I and II only
D
II and III only
correct option: d

The body while coming down is acted upon by acceleration due to gravity, hence, the vertical force is constant. Also, at maximum height, the vertical velocity is 0 and then increases as the body comes downward.

6

A body weighing 14N in air is partially immersed in water. If the mass of water displaced in the process is 200g, calculate the upthrust on the body. [g=10$$m/s^{2}$$]

A
2.0N
B
3.0N
C
3.5N
D
7.0N
correct option: a

Upthrust = weight of liquid displaced

= mass of liquid displaced $$\times$$ acceleration due to gravity

= $$\frac{200}{1000} \times 10$$

= 2N

7

Which of the following processes is not a surface phenomenon?

A
Condensation
B
Evaporation
C
Photo Emission
D
Thermionic Emission
correct option: a
8

A chemical balance is used for measuring

A
volume
B
mass
C
thickness
D
density
correct option: b

It is a type of beam balance with great precision, and it can pick up the slightest mass placed on it.

9

A body is whirled round a circular path at constant speed. Which of the following diagrams correctly indicates the direction of the body's velocity (v) and its acceleration (a)?

A
I
B
II
C
III
D
IV
correct option: b
10

A motorist travelling at 72$$kmh^{-1}$$ had his eyes shut for 0.4s during a hard sneeze. Calculate the distance covered by him during this time interval.

A
50.0m
B
28.8m
C
18.0m
D
8.0m
correct option: d

Convert velocity from $$kmh^{-1}$$ to $$ms^{-1}$$, by multiplying $$\frac{1000}{3600}$$,

$$72 \times \frac{1000}{3600}$$ = $$20ms^{-1}$$

Therefore, distance covered in 0.4s =  $$20 \times 0.4 = 8m$$