2005 - WAEC Physics Past Questions & Answers - page 1

1
Which of the following phenomena is the practical evidence for the existence of the continual motion of molecules?
A
Translational motion
B
rotational motion
C
brownian motion
D
oscillatory motion
CORRECT OPTION: c
2
Each of the following physical quantities is classified as a vector or a scalar quantity. Which of the classifications is correct?
A
electric potential (Vector)
B
momentum (scalar)
C
gravitational field intensity (scalar)
D
magnetic flux density (vector)
CORRECT OPTION: d
3
Which of the following statements about a spring balance and/or a chemical balance is not correct?
A
the chemical balance operates on the principle of moments
B
the sprin balance operates on Hooke's law
C
either may be used to measure the weight of a substance
D
the reading of a spring balance changes over the surface of the earth, while that of the chemical balance remaind constant
CORRECT OPTION: c
4
The friction which exists between two layers of liquid in relative motion is called
A
capillarity
B
surface tension
C
viscosity
D
cohension
CORRECT OPTION: c
5
A body of mass 25kg, moving at 3ms-1 on a rough horizontal floor is at rest after sliding through a distance of 2.50m on the floor. Calculate the co-efficient of sliding friction. [g = 10.0ms-2]
A
0.09
B
0.18
C
0.36
D
0.54
CORRECT OPTION: b
a = \(\frac{v^2 - u^2}{2a} = \frac{0^2 - 3^2}{2 \times 2.5}\) = 1.8m/s2

F = ma = 25 x 1.8 = 45N

but \(\mu = \frac{F}{R} = \frac{45}{25 \times 10} = 0.18\)
6
Which of the following simple machines is a second class lever?
A
wheel barrow
B
crowbar
C
claw hammer
D
seesae
CORRECT OPTION: a
7
A wheel and axle of radii 800mm and 200mm respectively is used to raise a body of weight 800N by the application of 250N. Calculate the efficiency of the machine
A
85%
B
80%
C
60%
D
20%
CORRECT OPTION: b
V.R = \(\frac{R}{r} = \frac{800}{200} = 4\)

M.A = \(\frac{L}{E} = \frac{800}{250} = 3.2\)

y = \(\frac{M.A}{v.R} \times \frac{100}{1} = 80\)%
8
Masses,m1 and m2 at the 20-cm and 65-cm marks respectively of a uniform metre rule freely suspended at its centre of gravity. If the metre rule balances horizontally, determine the ratio m2 : m1
A
2 : 1
B
3 : 3
C
2 : 3
D
1 : 2
CORRECT OPTION: d
9
Which of the following type of motion does a body undergo when acted upon by a couple?V
A
vibrational
B
translational
C
rotational
D
random
CORRECT OPTION: c
10
A body starts from rest and accelerates uniformly at 5ms-1 until it attains a velocity of 25ms-1. Calculate the time taken to attain this velocity
A
2.5s
B
5.0s
C
10.0s
D
125.0s
CORRECT OPTION: b
V = u + at = 25 = 0 + 5t

t = 5s
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