Free Work and Energy MCQs with Answers
748 Work and Energy MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Work transfers energy when a force causes displacement, while kinetic energy, gravitational potential energy and power describe motion, position and the rate of energy transfer. The work-energy theorem links net work with change in kinetic energy, and efficiency accounts for energy losses rather than treating them as energy destruction.
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Read the Work and Energy notesFree MDCAT chapter notes with key terms748 questions · page 5 of 38
- A. Stiffness
- B. Toughness
- C. Extension
- D. Deformation
Explanation: Deformation is any change in a body's shape or dimensions caused by an applied force, including changes in length, area or volume.
Correct answer: Deformation- A. Brittle
- B. Ductile
- C. Amorphous
- D. Polymers
Explanation: A ductile material can undergo substantial plastic deformation, meaning permanent deformation, before it fractures.
Correct answer: Ductile- A. 2 x 10^8 Nm-2
- B. 5 x 10^6 Nm-2
- C. 0.5 x 10^-6 Nm-2
- D. 0.2 x 10^-6Nm-2
Explanation: Young's modulus is Y = FL/(AΔL). Converting 2 cm^2 to 2 x 10^-4 m^2, Y = (10 N)(1 m)/[(2 x 10^-4 m^2)(0.01 m)] = 5 x 10^6 N m^-2.
Correct answer: 5 x 10^6 Nm-2- A. Nm-2
- B. Jm-2
- C. Nm-1
- D. Being a number it has no unit.
Explanation: Modulus of elasticity is stress divided by strain; strain has no unit, so its unit is the unit of stress, N m^-2, also called the pascal.
Correct answer: Nm-2- A. non-conservative force
- B. conservative force
- C. both A and B
- D. none of these
Explanation: Rocket thrust is produced by ejecting gases and depends on the changing mass and interaction of the rocket with its exhaust, so it is…
Correct answer: non-conservative force- A. area
- B. work done
- C. power
- D. none of these
Explanation: Work is the integral of force with respect to displacement, so the area under a force-displacement graph gives work done, measured in…
Correct answer: work done- A. torque
- B. angular momentum
- C. linear momentum
- D. power
Explanation: Work has dimensions force x distance, giving [M L2 T-2]. Torque is also force x perpendicular distance, so it has the same dimensions…
Correct answer: torque- A. frictional force
- B. gravitational force
- C. elastic force
- D. centripetal force
Explanation: Work is W = Fd cos θ. Centripetal force points toward the centre while instantaneous displacement is tangential, so θ = 90° and W = Fd cos…
Correct answer: centripetal force- A. electric field
- B. conservative field
- C. electromagnetic field
- D. gravitational field
Explanation: A conservative field has zero net work around every closed path, so the work depends only on the initial and final positions.
Correct answer: conservative field- A. 45°
- B. 90°
- C. 180°
- D. 0°
Explanation: Work is W = Fd cos θ. For fixed force and displacement, cos θ is greatest at θ = 0°, where W = Fd, so the work is maximum.
Correct answer: 0°- A. friction
- B. electric
- C. gravitational
- D. magnetic
Explanation: Friction is non-conservative because the work it does depends on the path and mechanical energy is converted into thermal energy.
Correct answer: friction- A. always positive
- B. always negative
- C. positive only for small frictional force
- D. positive only for large frictional force
Explanation: For ordinary friction opposing the motion, the angle between friction and displacement is 180°, so W = Fs cos 180° = -Fs, making the work…
Correct answer: always negative- A. force into small interval
- B. displacement into small interval
- C. both force and displacement into small intervals
- D. force into small and displacement into large intervals
Explanation: For a variable force, the displacement is divided into small intervals and the work over each interval is approximated by F Δs, then these…
Correct answer: displacement into small interval- A. zero
- B. minimum
- C. infinity
- D. maximum
Explanation: Work is W = Fs cos θ. When the force is parallel to displacement, θ = 0° and cos 0° = 1, so W = Fs, the maximum possible work for fixed…
Correct answer: maximum- A. Disc
- B. Loop
- C. Sphere
- D. All have the same speed
Explanation: The sphere has most of its mass near the axis of rotation, so it will have the smallest moment of inertia and will reach the ground…
Correct answer: Sphere- A. mg (x/h)
- B. mg (h/x)
- C. mg (1+h/x)
- D. mg (1 - h/x)
- E. mgh + mgd
Explanation: The work done by the resistive force of sand is given by:W = Fd = (1/2) kx2where F is the average resistive force offered by the sand on…
Correct answer: mg (h/x)- A. 30 cm
- B. 20 cm
- C. 10 cm
- D. 5 cm
Explanation: Let's use the equation of motion to find the additional distance the bullet will penetrate before coming to rest.
Correct answer: 10 cm98. Work is a:
- A. Vector quantity
- B. Scalar quantity
- C. Sometimes scalar sometimes vector
- D. None of these
Explanation: Work has only a magnitude but no direction. The formula for work is written as a dot product of force and displacement.
Correct answer: Scalar quantity- A. 4.00
- B. 1.00
- C. 0.25
- D. Impossible to determine
Explanation: Thermal efficiency (η) is the ratio of the useful work output to the total energy input.
Correct answer: 0.25- A. 10-25%
- B. 25-30%
- C. 30-40%
- D. 40-50%
Explanation: Due to thermodynamic limitations (like the Carnot cycle) and practical losses from friction and incomplete combustion, a typical…
Correct answer: 25-30%