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 22 of 38
421. Two bodies of masses 2m and 1m have their K.E. in the ratio 8: 1, then their ratio of momenta is:
- A. 1:1
- B. 4:1
- C. 2:1
- D. 8:1
Explanation: Use the relation: p = (2 * m * K.E)1/2 P 2m/P m = (2 * 2m * 8K.E)1/2 / (2 * m * K.E)1/2 This gives us the ratio 4:1.
Correct answer: 4:1422. The decrease in the potential energy of a ball of mass 20 kg which falls from a height of 50 cm is:
- A. 968 J
- B. 1980 J
- C. 98 J
- D. None of these
Explanation: To calculate the potential energy of the ball, we can use the formula for gravitational potential energy: Potential Energy (PE) = mass (m)…
Correct answer: 98 J- A. 0°
- B. 60°
- C. 30o
- D. 90°
Explanation: To find the angle between the force and the direction of motion of the body, we can use the work-energy principle, which states that the…
Correct answer: 60°- A. -7 joules
- B. +7 joules
- C. + 13 joules
- D. -11 joules
Explanation: Work done is given as W = F.d W= (5i - 3j) . (2i - 1j) W= 10 + 3 W= 13J
Correct answer: + 13 joules- A. The kinetic energy increases
- B. The kinetic energy remains the same
- C. The kinetic energy decreases
- D. The kinetic energy is zero
Explanation: Work dne on the body equals the change in its kinetic energy. If work done is positive KE inc. If work done is negative KE dec.
Correct answer: The kinetic energy increases- A. 200 Js-1
- B. 170 Js-1
- C. 40 Js-1
- D. 140 Js-1
Explanation: Power = Force · Velocity Force · Velocity = (10i + 10j + 20k) · (-3j + 5i + 6k) (10i + 10j + 20k) · (-3j + 5i + 6k)= (10 * (-3) + 10 * 5 +…
Correct answer: 140 Js-1- A. Work is positive on the way up, work is positive on the way down
- B. Work is negative on the way up, work is negative on the way down
- C. Work is negative on the way up, work is positive on the way down
- D. Work is positive on the way up, work is negative on the way down
Explanation: If displacement is in the direction of gravitational force, the work Is positive, as going downward.
Correct answer: Work is negative on the way up, work is positive on the way down428. The burning of coal, wood or natural gas and releasing of heat and light energy in the air is a
- A. nuclear reaction
- B. kinetic reaction
- C. chemical reaction
- D. potential reaction
Explanation: The burning of coal, wood, or natural gas and the release of heat and light energy into the air is a combustion process.
Correct answer: chemical reaction429. If the linear momentum of the object is increased by 0.1%, then the kinetic energy is increased by
- A. 0.1%
- B. 0.2%
- C. 0.4%
- D. 0.01%
Explanation: The linear momentum (p) of an object is given by the formula: p = mv, where m is the mass of the object and v is its velocity.
Correct answer: 0.2%- A. 6 m
- B. 12 m
- C. 18 m
- D. 24 m
Explanation: Option D is correct.Given data: velocity 1=v1 =50km/h velocity 2 = v2= 100km/hdisplacement 1=d1 =6m find out: d2=?
Correct answer: 24 m- A. t1/2
- B. t3/4
- C. t3/2
- D. t1/4
Explanation: Option C is correct.Yes, the distance moved by a body in time "t" is proportional to t3/2 when a machine delivers a constant power.
Correct answer: t3/2- A. 1 : 4
- B. 1 : 2
- C. 1 : √2
- D. √2 : 1
Explanation: Option B is correct.Given data: m1= 2kg, m2=4 kgh1= 60m ,h2=30mFind out: K.E1/K.E2=?Solution:According to the law of conservation of…
Correct answer: 1 : 2- A. Positive
- B. Zero
- C. Negative
- D. All of these
Explanation: Option D is correct. 1.The work done by the frictional force can be positive when the frictional force is in the same direction as the…
Correct answer: All of these- A. E1/E2=m1/m2
- B. E1 > E2
- C. E1=E2
- D. E1< E2
Explanation: Given that: Particle 1: Mass = m1, Velocity = v1 ,Momentum = m1v1 ,Kinetic Energy = (1/2)m1v1^2 Particle 2: Mass = m2, Velocity = v2…
Correct answer: E1< E2- A. 16 J
- B. 32 J
- C. 8 J
- D. 2 J
Explanation: Option A is correct.Given data: P=8 Ns , v=4ms-1 Ignoring massFind out: K.E.=?Solution:The formula for kinetic energy is: K.E = (1/2) *…
Correct answer: 16 J- A. Fd
- B. Zero
- C. -mgh
- D. mgh
Explanation: Option B is correct"The field in which work done on a body does not depend on the path followed by the body is called conservative…
Correct answer: Zero- A. Is positive
- B. Is negative
- C. Is zero
- D. Depends for its sign on the direction of the y axis
Explanation: During descent (downward motion) force of gravity and displacement are in the same direction. So, θ = 0°, cosθ = 1 W = Fd (+ve)
Correct answer: Is positive- A. The velocity of the object
- B. The kinetic energy of the object
- C. The mass of the object times its acceleration
- D. The mass of the object times its velocity
Explanation: By work energy principle Work done = ∆K.E
Correct answer: The kinetic energy of the object- A. mgh
- B. mgh/2
- C. Zero
- D. 2mgh
Explanation: In upward motionLoss in KE = Gain in P.EInitial K.E = mgh
Correct answer: mgh- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: At the extreme points, P and Q, the spring is not moving. So there is no kinetic energy at both points.
Correct answer: Option D