WBCS Mains Mechanics, Properties of Matter & Sound Questions 2023

Q. Which theorem/law can explain the working principle of a sprayer?

(A) Stokes’ Law
(B) Bernoulli’s Theorem
(C) Jurin’s Law
(D) Virial Theorem

Correct Answer: (B) Bernoulli’s Theorem.

Q. Fixed torque is applied to a body. What will be generated in the body?

(A) Angular acceleration
(B) Linear acceleration
(C) Angular velocity
(D) Angular displacement

Correct Answer: (A) Angular acceleration.

Q. Which of the following phenomena is not common to sound and light waves?

(A) Interference
(B) Diffraction
(C) Polarisation
(D) Reflection

Correct Answer: (C) Polarisation.

Q. Which one of the following is more elastic?

(A) Copper
(B) Rubber
(C) Sponge
(D) Steel

Correct Answer: (D) Steel.

Q. The frequency of a simple pendulum is f. What is the frequency of change in the energy of the pendulum?

(A) f/2
(B) f
(C) 2f
(D) 4f

Correct Answer: (C) 2f.

WBCS Mains Mechanics, Properties of Matter & Sound Questions 2022

Q. The velocity profile of a liquid flowing through a capillary is:

(A) Straight line
(B) Circular arc
(C) Hyperbolic
(D) Parabolic

Correct Answer: (D) Parabolic.

Q. Hydraulic press is based on:

(A) Archimedes’ Law
(B) Pascal’s Law
(C) Reynolds’ Law
(D) Bernoulli’s Law

Correct Answer: (B) Pascal’s Law.

Q. A bicycle in motion does not fall because one of the following is conserved:

(A) Linear momentum
(B) Angular momentum
(C) Kinetic energy
(D) All of the above

Correct Answer: (B) Angular momentum.

Q. Contact angle of mercury with respect to glass is:

(A) 0°
(B) 90°
(C) <90°
(D) >90°

Correct Answer: (D) >90°.

Q. Human ear is most sensitive to the sound of frequencies between:

(A) 100–500 Hz
(B) 500–5000 Hz
(C) 5000–10000 Hz
(D) 10000–20000 Hz

Correct Answer: (B) 500–5000 Hz.

WBCS Mains Mechanics, Properties of Matter & Sound Questions 2021

Q. Among the following, the weakest forces are:

(A) Gravitational forces
(B) Electric forces
(C) Magnetic forces
(D) Nuclear forces

Correct Answer: (A) Gravitational forces.

Q. Sound travels fastest in:

(A) Air
(B) Water
(C) Vacuum
(D) Steel

Correct Answer: (D) Steel.

Q. Lubricant cannot reduce:

(A) Static friction
(B) Kinetic friction
(C) Rolling friction
(D) Inertia

Correct Answer: (D) Inertia.

Q. Supersonic planes fly:

(A) With a speed less than the speed of sound
(B) With the speed of sound
(C) With a speed greater than the speed of sound
(D) With the speed of light

Correct Answer: (C) With a speed greater than the speed of sound.

Q. The surface tension of a liquid:

(A) Increases with area
(B) Decreases with area
(C) Increases with temperature
(D) Decreases with temperature

Correct Answer: (D) Decreases with temperature.

WBCS Mains Mechanics, Properties of Matter & Sound Questions 2020

Q. A person clapped his hands near a cliff and heard the echo after 2 s. What is the distance of the cliff from the person if the speed of sound is taken as 346 m/s?

(A) 173 m
(B) 346 m
(C) 692 m
(D) 1384 m

Correct Answer: (B) 346 m.

Q. Two bullets are fired simultaneously and horizontally from the same vertical height. The first bullet has mass and velocity m1 and v1 respectively and the second one has mass and velocity m2 and v2 respectively. Which bullet will hit the ground first?

(A) The faster one
(B) The slower one
(C) Both will reach simultaneously
(D) Will depend on masses

Correct Answer: (C) Both will reach simultaneously.

Q. An athlete completes one round of a circular track of diameter 200 m. What will be the distance covered (closest value among the options)?

(A) 528 m
(B) 628 m
(C) 314 m
(D) 1256 m

Correct Answer: (B) 628 m.

Q. Acceleration due to gravity of the Earth is maximum at:

(A) The center of the Earth
(B) The midpoint between the center and the surface of the Earth
(C) The surface of the Earth
(D) A height equal to the radius of the Earth from the surface of the Earth

Correct Answer: (C) The surface of the Earth.

Q. Which of the following frequencies is not in the audible range of sound for human beings?

(A) 5 Hz
(B) 50 Hz
(C) 500 Hz
(D) 5000 Hz

Correct Answer: (A) 5 Hz.

Q. A person travelling on a straight line moves with a uniform speed v1 for a distance x and with a uniform speed v2 for the next equal distance. The average speed v is given by:

(A) v = (v1 + v2) / 2
(B) v = √(v1v2)
(C) 2 / v = 1 / v1 + 1 / v2
(D) 1 / v = 1 / v1 + 1 / v2

Correct Answer: (C) 2 / v = 1 / v1 + 1 / v2.

Q. Gravitational force on the surface of the Moon is:

(A) 1/6 of that on the surface of the Earth
(B) 1/5 of that on the surface of the Earth
(C) 1/4 of that on the surface of the Earth
(D) 1/3 of that on the surface of the Earth

Correct Answer: (A) 1/6 of that on the surface of the Earth.

Q. A porter lifts a luggage of 15 kg from the ground and puts it on his head 1.5 m above the ground. The work done by him on the luggage is (g = 10 m/s²):

(A) 25 Joule
(B) 125 Joule
(C) 225 Joule
(D) 112.5 Joule

Correct Answer: (C) 225 Joule.

WBCS Mains Mechanics, Properties of Matter & Sound Questions 2019

Q. The potential energy of a molecule on the surface of a liquid compared to one inside the liquid is:

(A) Zero
(B) Lesser
(C) Equal
(D) Greater

Correct Answer: (D) Greater.

Q. A body is floating in a liquid at rest. Which of the following statements is incorrect?

(A) Buoyancy is equal to the weight of the body.
(B) Weight of the liquid displaced by the body is equal to the buoyancy.
(C) Force applied by the body on the liquid is equal and opposite to the buoyant force.
(D) Weight will be greater than buoyancy.

Correct Answer: (D) Weight will be greater than buoyancy.

Q. Water is flowing through a very narrow tube. The velocity of water below which the flow remains a streamline flow is known as:

(A) Relative velocity
(B) Terminal velocity
(C) Critical velocity
(D) Particle velocity

Correct Answer: (C) Critical velocity.

Q. A bullet, on penetrating 30 cm into its target, loses its velocity by 50%. What additional distance will it penetrate into the target before it comes to rest?

(A) 30 cm
(B) 20 cm
(C) 10 cm
(D) 5 cm

Correct Answer: (C) 10 cm.

Q. The value of the compressibility of an ideal fluid is:

(A) Zero
(B) Unity
(C) Infinity
(D) More than that of a real fluid

Correct Answer: (A) Zero.

Q. What is the shape of Earth’s orbit?

(A) Ellipse with high eccentricity
(B) Ellipse with low eccentricity
(C) Circle
(D) None of the above

Correct Answer: (B) Ellipse with low eccentricity.

WBCS Mains Mechanics, Properties of Matter & Sound Questions 2018

Q. Which material is used for the production of automobile springs requiring high elastic property?

(A) Copper
(B) Steel
(C) Brass
(D) All of the above

Correct Answer: (B) Steel.

Q. Sound waves having a frequency of more than 20,000 Hertz are known as:

(A) Ultrasonic
(B) Supersonic
(C) Microwave
(D) Seismic

Correct Answer: (A) Ultrasonic.

Q. Walking on a smooth floor may cause a fall because:

(A) The grip of the legs with the floor surface is minimized.
(B) Frictional force is nil.
(C) The centre of gravity of the body changes.
(D) Forwarding forces increase.

Correct Answer: (A) The grip of the legs with the floor surface is minimized.

Q. Quality of a musical note depends on:

(A) Fundamental frequency
(B) Harmonics
(C) Amplitude of the wave
(D) Velocity of sound

Correct Answer: (B) Harmonics.

WBCS Mains Mechanics, Properties of Matter & Sound Questions 2017

Q. Who first experimentally determined the value of the gravitational constant (G)?

(A) Newton
(B) Cavendish
(C) Galileo
(D) None of the above

Correct Answer: (B) Cavendish.

Q. A geostationary satellite has an orbital period of:

(A) 2 hours
(B) 6 hours
(C) 12 hours
(D) 24 hours

Correct Answer: (D) 24 hours.

Q. When milk is churned vigorously, the cream is separated due to:

(A) Frictional force
(B) Centrifugal force
(C) Centripetal force
(D) Gravitational force

Correct Answer: (B) Centrifugal force.

Q. The contact angle of mercury (Hg) on glass is:

(A) = 90°
(B) > 90°
(C) < 90°
(D) None of the above

Correct Answer: (B) > 90°.

WBCS Mains Mechanics, Properties of Matter & Sound Questions 2016

Q. Which type/types of pen uses/use capillary action in addition to gravity for the flow of ink?

(A) Fountain pen
(B) Ball point pen
(C) Gel pen
(D) Both ball point and gel pens

Correct Answer: (A) Fountain pen.

Q. If a bomb dropped from an airplane explodes in mid-air:

(A) Its kinetic energy increases.
(B) Its total energy increases.
(C) Its total energy decreases.
(D) None of the above

Correct Answer: (D) None of the above.

Q. Fat can be separated from milk in a cream separator because of:

(A) Cohesive force
(B) Gravitational force
(C) Centripetal force
(D) Centrifugal force

Correct Answer: (D) Centrifugal force.

Q. A small and a large raindrop are falling through air:

(A) The small drop moves faster.
(B) The large drop moves faster.
(C) Both move with the same speed.
(D) None of the above

Correct Answer: (B) The large drop moves faster.

Q. Weightlessness experienced in a spaceship is due to:

(A) Absence of inertia
(B) Absence of accelerating force
(C) Absence of gravity
(D) Free fall of the spaceship

Correct Answer: (D) Free fall of the spaceship.

Q. If the Earth stopped rotating, the value of ‘g’:

(A) Increases
(B) Decreases
(C) Remains unchanged
(D) Becomes zero

Correct Answer: (A) Increases.

WBCS Mains Mechanics, Properties of Matter & Sound Questions 2015

Q. If the radius of the Earth were to shrink by one percent, its mass remaining the same, the value of ‘g’ on the Earth’s surface would:

(A) Increase by 0.5%
(B) Increase by 2.0%
(C) Decrease by 0.5%
(D) Decrease by 2.0%

Correct Answer: (B) Increase by 2.0%.

Q. A weightless rubber balloon is filled with 200 c.c. of water. Its weight in water is equal to:

(A) 9.8/5 N
(B) 9.8/10 N
(C) 9.8/2 N
(D) Zero

Correct Answer: (D) Zero.

Q. A car is running on a road at a uniform speed of 60 km/h. The net resultant force on the car is:

(A) Driving force in the direction of motion of the car
(B) Resistance force in the direction opposite to the car’s motion
(C) An inclined force
(D) Equal to zero

Correct Answer: (D) Equal to zero.

Q. An artificial satellite orbiting around the Earth does not fall down because the attraction of the Earth:

(A) Does not exist at such distance
(B) Is neutralized by the attraction of the Moon
(C) Provides the necessary speed for its steady motion
(D) Provides the necessary acceleration for its motion

Correct Answer: (D) Provides the necessary acceleration for its motion.

WBCS Mains Mechanics, Properties of Matter & Sound Questions 2014

Q. Newton’s third law gives directly the law of conservation of:

(A) Momentum
(B) Energy
(C) Angular Momentum
(D) Power

Correct Answer: (A) Momentum.

Q. A body, falling freely from rest, covers a distance of 4 m in the first second. The acceleration due to gravity at that place is:

(A) 10.0 m/sec²
(B) 9.8 m/sec²
(C) 8.0 m/sec²
(D) 7.5 m/sec²

Correct Answer: (C) 8.0 m/sec².

Q. If the Earth-Sun distance is increased by a factor of four, the length of the year will increase approximately by a factor of:

(A) Two
(B) Four
(C) Eight
(D) Sixteen

Correct Answer: (C) Eight.