JAMB Physics 2021

The slope of the straight line displacement-time graph indicates?

A) distance travelled B) uniform velocity C) uniform acceleration D) uniform speed

Correct Answer: B) uniform velocity

A man will exert the greatest pressure when he?

A) lies flat on his back B) lies on his belly C) stands on both feet D) stands on the toes of one foot

Correct Answer: D) stands on the toes of one foot

Which of the units of the following physical quantities are derived? I. Area II. Thrust III. Pressure IV. Mass

A) I, II, III and IV B) I, II and III only C) I, II and IV only D) I and IV only

Correct Answer: B) I, II and III only

A ball of mass 0.5kg moving at 10 m/s collides with another ball of equal mass at rest. If the two balls move together after impact, calculate their common velocity.

A) 0.2 m/s B) 0.5 m/s C) 5.0 m/s D) 10 m/s

Correct Answer: C) 5.0 m/s

The motion of a body is simple harmonic if the?

A) acceleration is always directed towards a fixed point B) path of motion is a straight line C) acceleration is proportional to the square of the distance D) acceleration is constant

Correct Answer: A) acceleration is always directed towards a fixed point

Which of the following is not correct about molecules in a gaseous state?

A) constant motion B) different speeds C) temperature related to kinetic energy D) collisions are perfectly inelastic

Correct Answer: D) collisions are perfectly inelastic

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?

A) 46.0 Nm^-2 B) 75.0 Nm^-2 C) 80.0 Nm^-2 D) 85.3 Nm^-2

Correct Answer: B) 75.0 Nm⁻²

0.5kg of water at 10°C is completely converted to ice at 0°C by extracting 88,000J of heat. If the specific heat capacity of water is 4200 Jkg^-1C^-1, calculate the specific latent heat of fusion of ice.

A) 9.0 kJkg⁻¹ B) 84.0 kJkg⁻¹ C) 134.0 kJkg⁻¹ D) 168.0 kJkg⁻¹

Correct Answer: C) 134.0 kJkg⁻¹

Which of the following instruments may be used to measure relative humidity?

A) Hydrometer B) Manometer C) Hygrometer D) Hypsometer

Correct Answer: C) Hygrometer

A source of sound produces waves in air of wavelength 1.65m. If the speed of sound in air is 330 ms⁻¹, the period of vibration is?

A) 200 B) 0.005 C) 0.5 D) 0.02

Correct Answer: B) 0.005

A boy standing some distance from a tall cliff claps his hands and hears an echo 0.5s later. If the speed of sound is 340 ms⁻¹, how far is he from the cliff?

A) 680m B) 170m C) 34m D) 85m

Correct Answer: D) 85m

Which of the following is not a vector quantity?

A) momentum B) force C) temperature D) displacement

Correct Answer: C) temperature

Calculate the heat energy required to vaporise 50g of water initially at 80°C. (Specific heat capacity of water = 4.23 Jg⁻¹K⁻¹, latent heat of vaporisation = 2260 Jg⁻¹)

A) 530000J B) 23200J C) 17200J D) 130000J

Correct Answer: D) 130000J

In a series R-L-C circuit at resonance, the voltages across the resistor and inductor are 30V and 40V respectively. What is the voltage across the capacitor?

A) 30V B) 40V C) 50V D) 70V

Correct Answer: B) 40V

If the frequency of an emitted X-ray is 1.6 × 10¹⁶ Hz, the accelerating potential is? (e = 1.6 × 10^-19 J, h = 6.63 × 10^-34 Js)

A) 6630.0V B) 663.0V C) 66.3V D) 6.6V

Correct Answer: C) 66.3V

If the fraction of atoms of a radioactive material left after 120 years is 1/64, what is the half-life of the material?

A) 24 years B) 20 years C) 10 years D) 2 years

Correct Answer: B) 20 years

A certain radioactive source emits radiation that is deflected by both magnetic and electric fields. The radiation is?

A) beta rays B) gamma rays C) x-rays D) ultra-violet rays

Correct Answer: A) beta rays

The inner diameter of a test tube can be measured accurately using a?

A) micrometer screw gauge B) pair of dividers C) metre rule D) pair of vernier calipers

Correct Answer: D) pair of vernier calipers

Two bodies have masses in the ratio 3:1. They experience accelerations in the ratio 2:9 respectively. Find the ratio of the forces acting on them.

A) 1:4 B) 2:1 C) 2:3 D) 2:5

Correct Answer: C) 2:3

A particle of mass 10kg is fixed to the tip of a fan blade rotating with angular velocity 100 rad s⁻¹. If the radius is 0.2m, the centripetal force is?

A) 2N B) 20N C) 200N D) 400N

Correct Answer: B) 20N

A lead bullet of mass 0.05kg is fired with velocity 200 m/s into a block of mass 0.95kg which can move freely. The final kinetic energy after impact is?

A) 50J B) 100J C) 150J D) 200J

Correct Answer: A) 50J

A ball of mass 0.1kg is thrown vertically upward with speed 10 m/s from the top of a tower 10m high. Neglecting air resistance, its total energy just before hitting the ground is?

A) 5J B) 10J C) 15J D) 20J

Correct Answer: C) 15J

A car of mass 800kg attains a speed of 25m/s in 20s. The power developed in the engine is?

A) 1.25 × 10⁴ W B) 2.50 × 10⁴ W C) 1.25 × 10⁶ W D) 2.50 × 10⁶ W

Correct Answer: B) 2.50 × 10⁴ W

When the brakes of a car are applied, the frictional force on the tyres is?

A) disadvantage because it is in the direction of motion B) disadvantage because it is opposite to motion C) advantage because it is in direction of motion D) advantage because it is opposite to motion

Correct Answer: D) advantage because it is opposite to motion

If the stress on a wire is 10⁷ Nm⁻² and the wire stretches from 10.00m to 10.05m, the Young's modulus of the wire is?

A) 5.0 × 10^-4 Nm^-2 B) 5.0 × 10^-5 Nm^-2 C) 2.0 × 10^-8 Nm^-2 D) 2.0 × 10⁹ Nm^-2

Correct Answer: D) 2.0 × 10⁹ Nm⁻²

A solid weighs 10N in air, 6N when immersed in water, and 7N when immersed in liquid X. Calculate the relative density of liquid X.

A) 5/3 B) 4/3 C) 3/4 D) 7/10

Correct Answer: C) 3/4

When the temperature of a liquid increases, its surface tension?

A) decreases B) increases C) remains constant D) increases then decreases

Correct Answer: A) decreases

A gas at volume V and pressure P₀ is compressed to one-fifth of its volume while temperature remains constant. What is the new pressure?

A) P₀/5 B) 4P₀/5 C) P₀ D) 5P₀

Correct Answer: D) 5P₀

A substance with specific heat capacity 450 Jkg⁻¹K^-1 falls through a height of 20m. Calculate the rise in temperature if all energy converts to heat. (g = 10 m/s²)

A) 29°C B) 49°C C) 92°C D) 94°C

Correct Answer: B) 49°C

Which statements describe boiling point properties of a liquid? I. Boiling occurs when vapour pressure equals external pressure. II. Dissolved substances increase boiling point. III. Increasing external pressure increases boiling point. IV. Dissolved substances decrease boiling point.

A) I, II and III only B) I, II, III and IV C) I, II and IV D) II, III and IV

Correct Answer: A) I, II and III only

The temperature gradient across a copper rod of thickness 0.02m maintained at 20°C and 80°C is?

A) 3.0 × 10² Km⁻¹ B) 3.0 × 10³ Km⁻¹ C) 5.0 × 10² Km⁻¹ D) 3.0 × 10⁴ Km⁻¹

Correct Answer: B) 3.0 × 10³ Km⁻¹

Calculate the mass of ice melted when 2kg of copper at 100°C is placed on ice. (c = 400 Jkg⁻¹, Lf = 3.3 × 10⁵ Jkg⁻¹)

A) 0.24 kg B) 3.38 kg C) 8.03 kg D) 0.03 kg

Correct Answer: A) 0.24 kg

For the wave equation y = 0.25×10⁻³ sin(500t − 0.025x), determine the angular velocity.

A) 0.25 × 10³ rad/s B) 0.25 × 10⁻¹ rad/s C) 5.00 × 10² rad/s D) 2.50 × 10³ rad/s

Correct Answer: C) 5.00 × 10² rad/s

If a sound wave travels from cold air to hot air, its wavelength will?

A) increase B) decrease C) decrease then increase D) remain constant

Correct Answer: A) increase

The lowest frequency from a stretched string is 40Hz. How many overtones exist between 40Hz and 180Hz?

A) 4 B) 3 C) 2 D) 1

Correct Answer: B) 3

A man stands 4m in front of a plane mirror. If the mirror moves 1m towards him, the distance between him and his image is?

A) 3m B) 5m C) 6m D) 10m

Correct Answer: C) 6m

The velocity of light in air is 3.0×10⁸ m/s and in glass 2.0×10⁸ m/s. If angle of refraction is 30°, find sin(i).

A) 0.33 B) 0.50 C) 0.67 D) 0.75

Correct Answer: D) 0.75

An astronomical telescope is in normal adjustment when the?

A) eye is accommodated B) focal length of objective is longer than eyepiece C) final image at near point D) final image at infinity

Correct Answer: D) final image at infinity

A 2H inductor is connected to a 50π Hz AC supply. The reactance is?

A) 200Ω B) 50Ω C) 100/π Ω D) 25/π Ω

Correct Answer: A) 200Ω

An astronomical telescope is said to be in normal adjustment when the?

A) eye is accommodated B) focal length of objective is longer than eyepiece C) final image at near point D) final image at infinity

Correct Answer: D) final image at infinity