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 4 of 38
- A. power
- B. work
- C. impulse
- D. torque
Explanation: Instantaneous power is the dot product of force and velocity: P = F · v, measured in watts.
Correct answer: power- A. [ML2T-3]
- B. [ML2T-2]
- C. [ML2T3]
- D. none of these
Explanation: Power is work divided by time. Since work has dimensions [M L2 T-2], power has dimensions [M L2 T-2]/T = [M L2 T-3], which is option a.
Correct answer: [ML2T-3]- A. 120 J
- B. 60 J
- C. 30 J
- D. 0.02 J
Explanation: Power is the rate of energy consumption, so energy = power x time = 60 W x 2 s = 120 J.
Correct answer: 120 J- A. any rate
- B. at variable rate
- C. at uniform rate
- D. at high rate
Explanation: Average power is total work divided by total time, while instantaneous power is the rate of doing work at a particular instant.
Correct answer: at uniform rate- A. IRt
- B. I2R
- C. I2Rt
- D. VIt
Explanation: The rate at which electrical energy is converted into heat is electrical power, P = I²R, measured in watts (W).
Correct answer: I2R- A. watt
- B. horse power
- C. kilo watt
- D. kilowatt hour
Explanation: Electrical energy used by homes and appliances is commonly measured in kilowatt-hours (kWh), where 1 kWh = 1000 W used for 1 hour.
Correct answer: kilowatt hour- A. 12
- B. 24
- C. 5
- D. 1100
Explanation: The energy consumed is E = Pt = 500 W x 24 h = 12000 Wh = 12 kWh, so the answer is 12 units of electrical energy.
Correct answer: 12- A. 144000J
- B. 144J
- C. 1.44J
- D. 14J
Explanation: Electrical energy is calculated from E = Pt: 40 W x 1 h x 3600 s/h = 144000 J.
Correct answer: 144000J- A. one second
- B. one day
- C. one minute
- D. one hour
Explanation: One kilowatt-hour is the energy supplied by a power of 1 kilowatt operating for 1 hour, so the time interval is one hour.
Correct answer: one hour- A. more heat is produced in thick wire
- B. more heat is produced in thin wire
- C. no heat is produced in wire
- D. less heat is produced in thick wire
Explanation: For the same current and time, heat produced is H = I²Rt. A thin wire of the same material and length has greater resistance because its…
Correct answer: more heat is produced in thin wire- A. 22N
- B. 16N
- C. 20N
- D. 4N
Explanation: The hand does work equal to the ball's gain in gravitational potential energy while it moves 0.2 m and then rises a further 2.0 m: F x 0.2…
Correct answer: 22N- A. to smooth out the energy variation
- B. to add more weight to engine to work it stable
- C. to start engine
- D. both A and BEngine & Transmission
Explanation: A flywheel stores rotational kinetic energy when the engine produces excess torque and releases it when torque falls, smoothing energy and…
Correct answer: to smooth out the energy variation- A. E=mc2
- B. Vf=Vi+at
- C. S=Vt2
- D. S=1/2at2
Explanation: In S = Vt², the right side has dimensions (m s^-1)(s²) = m s, which is not a length.
Correct answer: S=Vt2- A. Deriving a possible formula
- B. Checking the homogeneity of a physical equation
- C. Verification of laws
- D. Only A and B are correct
Explanation: Dimensional analysis can suggest a possible formula and can test whether both sides of an equation have the same dimensions.
Correct answer: Only A and B are correct75. The ration stress to strain in youngs modulus of the material then tension is__________________?
- A. Directly proportional to extension
- B. Directly proportional to strain
- C. Directly proportional to square of amplitude
- D. Inversely proportional to extension
Explanation: Within the elastic limit, Young's modulus remains constant, so stress is proportional to strain.
Correct answer: Directly proportional to extension- A. 3.5 x 10^-3 J
- B. 3.5 x 10^4 J
- C. 3.5 x 10^6 J
- D. 3.5 x 10^9 J
Explanation: With no friction, the work done in raising the elevator equals force times vertical distance: W = Fd = (3.5 x 10^-6 N)(1000 m) = 3.5 x…
Correct answer: 3.5 x 10^-3 J- A. Work
- B. Energy
- C. Power
- D. Momentum
Explanation: Energy is defined as the capacity of a body or system to do work, and it is measured in joules (J).
Correct answer: Energy- A. It's works equals the change in the kinetic energy of the particle.
- B. It's obeys Newton's second law
- C. It's obeys Newton's third law
- D. It work depends on the end points of every motion, not on the path between.
Explanation: A conservative force does work that depends only on the initial and final positions, not on the path taken between them.
Correct answer: It work depends on the end points of every motion, not on the path between.- A. at any instant
- B. averagely
- C. during its operation
- D. during one cycle
Explanation: On a pressure-volume diagram, the area enclosed by a complete cycle equals the net work done, because work is found from the integral of…
Correct answer: during one cycle- A. Maximum work
- B. Minimum work
- C. Negative work
- D. No work
Explanation: Centripetal force acts radially inward, while instantaneous displacement is tangential to the circle.
Correct answer: No work