JAMB - Physics (2021)

1
The slope of the straight line displacement-time graph indicates?
Відповідь
(B)
uniform velocity
2
A man will exert the greatest pressure when he?
Відповідь
(D)
stands on the toes of one foot
3
Which of the units of the following physical quantities are derived?

I. Area
II. Thrust
III. Pressure
IV. Mass
Відповідь
(B)
I, II, and III only
4
A ball of mass 0.5kg moving at 10ms\(^{-1}\) collides with another ball of equal mass at rest. If the two balls move off together after the impact, calculate their common velocity.
Відповідь
(C)
5.0ms\(^{-1}\)
5
The motion of a body is simple harmonic if the?
Відповідь
(A)
acceleration is always directed towards a fixed point
6
Which of the following is not correct about the molecules of a substance in a gaseous state. They?
Відповідь
(D)
The collision between the gases is perfectly inelastic
7
A given mass of gas has a pressure of 80 Nm\(^{-2}\) at a temperature of 47 C. If the temperature is reduced to 27 C with volume remaining constant, the new pressure is?
Відповідь
(B)
75.0 Nm\(^{-2}\)
8
0.5kg of water at 10ºC is completely converted to ice at 0ºC by extracting (88000) of heat from it. If the specific heat capacity of water is 4200jkg\(^{1}\) Cº. Calculate the specific latent heat of fusion of ice.
Відповідь
(C)
134.0kjkg\(^{-1}\)
9
Which of the following instruments may be used to measure relative humidity?
Відповідь
(C)
Hygrometer
10
A source of sound produces waves in air of wavelength 1.65m. If the speed of sound in air is 330ms\(^{-1}\), the period of vibration in air is?
Відповідь
(B)
0.005
11
A boy standing some distance from the foot of a tall cliff claps his hands and hears an echo 0.5s later. If the speed of sound is 340ms\(^{-1}\), how far is he from the cliff?
Відповідь
(D)
85m
12
Which of the following is not a vector quantity?
Відповідь
(C)
temperature
13
Calculate the heat energy required to vaporize 50g of water initially at 80ºC if the specific heat capacity of water is 4.23jg\(^{-1}\)k\(^{-1}\) (specific latent heat of vaporization of water is 2260jg\(^{-1}\)
Відповідь
(D)
130000J
14
In a series R-L-C circuit at resonance, the voltages across the resistor and the inductors are 30V and 40V respectively. What is the voltage across the capacitor?
Відповідь
(B)
40V
15
If the frequency of an emitted x-ray is 1.6 x 10\(^{16}\)Hz, the accelerating potential is?

[e = 1.6 x 10\(^{-19}\)J, h = 6.63 x 10-\(^{34}\)Js]
Відповідь
(C)
66.3V
16
If the fraction of the atoms of a radioactive material left after 120 years is 1/64, what is the half-life of the material?
Відповідь
(B)
20 years
17
A certain radioactive source emits radiation that was found to be deflected by both magnetic and electric fields. The radiation is?
Відповідь
(A)
beta rays
18
The inner diameter of a test tube can be measured accurately using a?
Відповідь
(D)
pair of vernier calipers
19
Two bodies have masses in the ratio3:1. They experience forces which impart to them, acceleration in the ratio 2:9 respectively. Find the ratio of forces the masses experienced
Відповідь
(C)
2:3
20
Particles of mass 10\(^{-2}\)kg is fixed to the tip of a fan blade which rotates with angular velocity of 100rad\(^{-1}\). If the radius of the blade is 0.2m, the centripetal force is?
Відповідь
(B)
20N
21
A lead bullet of mass 0.05kg is fired with a velocity of 200ms\(^{-1}\) into a block of mass 0.95kg. Given that the lead block can move freely, the final kinetic energy after impact is?
Відповідь
(A)
50J
22
A ball of mass 0.1kg is thrown vertically upwards with a speed of 10ms\(^{-1}\) from the top of a tower 10m high. Neglecting air resistance, its total energy just before hitting the ground is? (Take g = 10ms\(^{-2}\))
Відповідь
(C)
15J
23
A car of mass 800kg attains a speed of 25m/s in 20secs. The power developed in the engine is?
Відповідь
(B)
2.50x 10\(^{4}\)W
24
When the breaks in a car are applied, the frictional force on the tyres is?
Відповідь
(D)
an advantage because it is in the opposite direction of the motion of the car
25
If the stress on a wire is 10\(^{7}\)NM\(^{-2}\) and the wire is stretched from its original length of 10.00m to 10.05m. The young's modulus of the wire is?
Відповідь
(D)
2.0 x 10\(^{9}\)Nm\(^{-2}\)
26
A solid weighs 10.00N in air, 6N when forcefully immersed in water, and 7.0N when fully immersed in a liquid, X. Calculate the relative density of the liquid X.
Відповідь
(C)
\(\frac{3}{4}\)
27
When the temperature of a liquid increases, its surface tension
Відповідь
(A)
decreases
28
A gas at a volume of V\(_{0}\) in a container at pressure p\(_{0}\) is compressed to one-fifth of its volume. What will be its pressure if the magnitude of its original temperature T is constant?
Відповідь
(D)
5P\(_{0}\)
29
A piece of substance of specific heat capacity 450Jkg\(^{-1}\)k\(^{1}\) falls through a vertical distance of 20m from rest. Calculate the rise in temperature of the substance on hitting the ground when all its energies are converted into heat. [g = 10ms\(^{-2}\)]

Відповідь
(B)
\(\frac{4}{9}\)ºC
30
I. A liquid boils when its saturated vapor pressure is equal to the external pressure
II. Dissolved substances in pure water lead to an increase in the boiling point.
III. When the external pressure is increased, the boiling point increases.
IV. Dissolved substances in pure water decreases the boiling point

Which of the above combinations are peculiarities of the boiling point of a liquid?
Відповідь
(A)
I, II and III only
31
The temperature gradient across a copper rod of thickness 0.02m, maintained at two temperature junctions of 20º and 80ºC respectively is?
Відповідь
(B)
3.0 x 10\(^{3}\)km\(^{-1}\)
32
Calculate the mass of ice that would melt when 2kg of copper is quickly transferred from boiling water to a block of ice without heat loss (specific heat capacity of copper = 400Jkg\(^{1}\)k\(^{-1}\), latent heat of fusion of ice = 3.3 x 10\(^{5}\)Jkg\(^{-1}\))
Відповідь
(A)
\(\frac{8}{33}\)kg
33
The equation of a wave traveling along the positive x-direction is given by; y = 0.25 x 10\(^{-3}\) sin (500t - 0.025x). Determine the angular velocity of the wave motion.
Відповідь
(C)
5.00 x 10\(^{2}\)rads\(^{-1}\)
34
If a sound wave goes from a cold air region to a hot air region, its wavelength will?
Відповідь
(A)
increase
35
The lowest note emitted by a stretched string has a frequency of 40Hz. How many overtones are there between 40Hz and 180Hz?
Відповідь
(B)
3