2008 - JAMB Physics Past Questions & Answers - page 1

1
I. Force (N)
II.Torque (NM)
III. Current (A)
IV. Power (W)
Which of the above are the correct S. I: units of the quantities indicated?
A
I and II only
B
I and III only
C
I, II and III only
D
I, III and IV only
CORRECT OPTION: d
Torque has the same unit as moment = Nm
∴i, iii and iv have correct units.
2
Which of the following is NOT a vector quantity?
A
altitude
B
acceleration
C
displacement
D
weight
CORRECT OPTION: a
Altitude is just a measure of height, regardless of direction.
3
If a wheel 1.2 m in diameter rotates at one revolation per second, calculate the velocity of the wheel.
A
3.6 ms-1
B
3.77 ms-1
C
4.0 ms-1
D
7.5 ms-1
CORRECT OPTION: b
V = wr = 2πf r = 2 x (22)/7 x 1 x 0.6
= 3.77ms-1
4
I. All the three forces must be concurrent.
II. The upward force is equal to the downward force.
III. The algebraic sum of the moment about any point must be zero.

which of the above conditions must hold for a body acted upon by a system of three coplanar forces equilibrium?
A
I and II only
B
I and III only
C
II and III only
D
I, II and III
CORRECT OPTION: b
Option ii is one of the condition of an equilibrium of parallel forces only i and iii are correct
5
What is the frquency of vibration if the balance wheel of a wrist watch makes 90 revolutions in 25 s?
A
0.01 Hz
B
0.04 Hz
C
2.27 Hz
D
3.60 Hz
CORRECT OPTION: d
Frequency = (No. of revolutions)/ Time = (90)/25 = 3.6 Hz
6
If a body mass 5kg is thrown vertically upwards with velocity u,at what height will the potential energy equal to the kinetic energy?
A
h =(u)2/g
B
h = (u)2/4g
C
h = (2u)2/g
D
h = (u)2/2g
CORRECT OPTION: b
From V2 = U2 + 2as
O = U 2 - 2gH, since at maximum height H, the final velocity, v = O.
∴ H = (U)2/2g
PE = KE at (1)/2 H = (U)2/2g x (1)/2 = U2 4g
7
counting of currency notes with moist fingers is based on the principles of?
A
diffusion
B
cohesion
C
adhesion
D
viscosity
CORRECT OPTION: c
since currency and finger contain unlike molecules, the force involved is adhesion
8
A motorcycle of mass 100kg moves round in a circle of radius 10m with a velocity of 5 ms-1. find the coefficient of friction between the road and the tyres.
A
25.00
B
2.50
C
0.50
D
0.25
CORRECT OPTION: d
F = (mv)2/r = (100 x 5)2 = 250N
R = mg = 100 x 10 - 1000N
coefficient of friction,
µ = (F)/R = (250)/1000 = 0.25
9
A spring of force constant 500 NM-1 is compressed such that its length shortens by 5cm. The energy stored in the spring is?
A
0.625 J
B
6.250 J
C
62.500 J
D
625.000 J
CORRECT OPTION: a
Energy stored in a spring = (1)/2 K e2 = (1)/2 x 500(0.05)2 = 0.625J
10
In the hare's apparatus, water rises to a height of 26.5 cm in one limb. if a liquid rises to a height of 20.4 cm in the other limb, what is the relative density of the liquid?
A
0.8
B
1.1
C
1.2
D
1.3
CORRECT OPTION: d
hlpl = hwpw
where, L =liquid and W = water
(pl)/pw = (hw)/hl = (26.5)/20.4
= 1.299
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