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 10 of 38
- A. Man has more power than child
- B. Both have same power
- C. Child has more power than man
- D. It is a foolish question
Explanation: Wman = mgh = (40)(10)(1) = 400 JP = Wman / t = 400 / 10 = 40 wattWchild = mgh = (10)(10)(1) = 100 JP = Wchild / t = 100 / 1 = 100 watt
Correct answer: Child has more power than man- A. 5 W
- B. 40 W
- C. 60 W
- D. 500 W
Explanation: The power of a machine is calculated using the formula: Power = Work / Time.
Correct answer: 5 W183. An elevator lifts a weight of 400 N through a height of 10 m in 20 s. The power of the motor is
- A. 200 W.
- B. 800 W.
- C. 4000 W.
- D. 8000 W.
Explanation: To calculate the power of the motor, you need to find the work done and then divide it by the time.
Correct answer: 200 W.- A. 40 J.
- B. 90 J.
- C. 2400 J.
- D. 144000 J.
Explanation: Energy (E) = Power (P) × Time (t)Given:Power (P) = 40 WTime (t) = 1 hourFirst, convert the time from hours to seconds, as 1 Watt is equal…
Correct answer: 144000 J.- A. 10 W
- B. 15 W
- C. 20 W
- D. 25 W
Explanation: This is correct because power = work ÷ time = 300 ÷ 20 = 15 W.
Correct answer: 15 W- A. Joule
- B. Newton
- C. Watt
- D. Pascal
Explanation: This is correct because watt (W) is defined as 1 joule per second, the SI unit for power.
Correct answer: Watt- A. 70 J
- B. 270 J
- C. 35 J
- D. 135 J
Explanation: W = ∫ F . dx = ∫ from 0 to 5 (7 - 2x + 3x²) dx= [ 7x - (2x²)/2 + (3x³)/3 ] from 0 to 5 = 35 - 25 + 125 = 135 J
Correct answer: 135 J- A. Power
- B. Energy
- C. Density
- D. Force
Explanation: The rate at which work is done is called power. It is expressed as the amount of work per unit of time.
Correct answer: Power- A. 37.2 x 10^-19 joule
- B. 27.702 x 10^-19 joule
- C. 17.70 x 10^-19 joule
- D. 7.702 x 10^-29 joule
Explanation: The following is the solution:speed of neutron = distance travelled by neutron / time taken by neutron for covered that distance .speed of…
Correct answer: 37.2 x 10^-19 joule- A. It is squared
- B. It is halved
- C. It is doubled
- D. It does not change
Explanation: Power = force * velocityWith velocity kept constant, Power is directly proportional to force. Therefore, doubling force would double power.
Correct answer: It is doubled- A. The force of friction
- B. The force of gravity
- C. The normal force
- D. The force you are pushing
Explanation: As the crate is moving at a constant speed, the net force is 0. The total of the forces exerted on the crate down the slope is equal to…
Correct answer: The force of friction- A. 100 J
- B. 200 J
- C. 300 J
- D. 400 J
Explanation: Work done = change in KEWork done = 1/2 m (v22 - v12)Work done = 1/2 x 10 x (82 - 22)Work done = 1/2 x 10 x (64 - 4)Work done = 300 J
Correct answer: 300 J- A. 2000 J
- B. 4000 J
- C. 20000 J
- D. 40000 J
Explanation: According to the given data; m=20 g = 0.02 kg , v= 2000 m/s2 K.E = 1/2 mv2 = 1/2 (0.02)(2000)2 =40,000 J
Correct answer: 40000 J- A. The path taken by the suitcase
- B. Initial and final position
- C. Weight of the suitcase
- D. None
Explanation: Option A is correct. Work done is conservative as it doesn't depends on path followed by body.
Correct answer: The path taken by the suitcase- A. 1/9 times
- B. 1/3 times
- C. 6 times
- D. 9 times
Explanation: K.E = 1/2 x m x v2If mass remains constant, thenK.E ∝ v2So, if speed is tripled, thenK.E' ∝ (3)2 = 9K.E' / K.E = 9 / 1K.E' = 9 K.EK.E will…
Correct answer: 9 times196. 1 kilowatt hour =
- A. 1.6 x 10^-19 J
- B. 3.6 x 10^6 J
- C. 9.1 x 10^31J
- D. 1.67 x 10^-27 J
Explanation: The commercial unit of electrical energy is a kilowatt-hour (kWh). The energy generated by a kilowatt power source in 1 hour is 1 kWh.1kWh…
Correct answer: 3.6 x 10^6 J- A. 2mgh
- B. 3mgh
- C. 4mgh
- D. 6mgh
Explanation: The work done on the blocks in stacking them on top of one another is equal to the force required to lift each block multiplied by the…
Correct answer: 6mgh- A. 50J
- B. 75 J
- C. 100 J
- D. 150 J
Explanation: According to the given data;Force= 15N , angle of application of force= 60° , displacement covered= 10mWork= Force x displacement x cos(θ)…
Correct answer: 75 J- A. Force and displacement
- B. Force and time
- C. Force and velocity
- D. Force and mass
Explanation: Power =F→ .v→Power is dot product of force and velocity.
Correct answer: Force and velocity- A. Frictional force
- B. Centripetal force
- C. Gravitational force
- D. Restoring force
Explanation: W = F.dW = Fcd Cosθ = Fd cos90º=Fcd (0)= 0Due to centripetal force the object will move in a circular path.
Correct answer: Centripetal force