Free Work and Energy MCQs with Answers

• A. 120 W
• B. 60 W
• C. 300 W
• D. 294 W

Explanation: We use the formula of power, P = W/t = mgh/tP = PE/t = mgh/t = (60)(10)(10)/20 = 300 wattHence, this is the correct option.

• A. -75 J
• B. -73.5 J
• C. 73.5 J
• D. 75 J

Explanation: The correct answer is 75 J. To find the work done against gravity, you use the formula W = m * g * h.

• A. 16/25
• B. 2/5
• C. 3/5
• D. 9/2

Explanation: According to the law of conservation of energy energy, can neither be created nor be destroyed.

• A. 1000 kg/s
• B. 2000 kg/s
• C. 4000 kg/s
• D. 5000 kg/s

Explanation: The formula of power isPower = W/t = PE/t = mgh/tm/t = P/gh = 10⁶/(10)(20) = 5000 kg/sHence, this option is correct.

• A. 0°
• B. 45°
• C. 30°
• D. 60°

Explanation: Work done by a force is calculated as W = Fdcosθ, where θ is the angle between the force and the direction of displacement.

• A. 20 J
• B. 32 J
• C. 26 J
• D. Zero

Explanation: W = F . d= (3 i + 2 j + 4 k) . (10 j)W = 20 J

• A. 0o
• B. 30o
• C. 45o
• D. 60°

Explanation: W = F d cosθθ = cos⁻¹ ( W / Fd )= cos⁻¹ ( 25 / (10 × 5) )= cos⁻¹ ( 1/2 )θ = 60°.

• A. 1: 2
• B. 1 : 16
• C. 1 : 4
• D. 1 : 1

Explanation: Kinetic energy, momentum and mass are related as:KE = P²/2mP² = KE × 2mAs KE1 = KE2, the ration will become,P1²/P2² = m1/m2P1/P2 = √m1/√m2…

• A. 5 x 10^7 J
• B. 5 x 10^-2 J
• C. 5 x 10^8 J
• D. 5 x 100 J

Explanation: Momentum, kinetic energy and velocity are related asKE = 1/2pv = 1/2 (10000×10-2)/1000×(10000×10-2)KE = 1/2(10000/1000) = 5JHence, this…

• A. 10J
• B. 180 J
• C. 90 J
• D. 270 J

Explanation: K.E₁ / K.E₂ = v₁² / v₂²K.E₂ = K.E₁ (v₂² / v₁²)K.E₂ = 30 × 900 / 100 = 270 J

• A. 324J
• B. 486 J
• C. 256 J
• D. 524 J

Explanation: Final Answer: 486 J1. Apply conservation of momentum:0 = m1 v1 + m2 v20 = 18 × 6 + 12 × v2v2 = - (18 × 6) / 12 = -9 m/s2. Calculate K.E.

• A. 10 J
• B. 15 J
• C. 40 J
• D. 150 J

Explanation: W = n (n - 1) / 2 * mgh = 10 (10 - 1) / 2 * mgh = 45 mghW = 40 J

• A. The kinetic energy of the ball is greatest at the greatest height attained
• B. The potential energy of the ball increase uniformly with time during the ascent.
• C. By the principle of conservation of momentum, the momentum of the ball is constant throughout its motion
• D. By the principle of conservation of energy, the total energy of the ball is constant throughout its motion

Explanation: By principle of conservation of energy, total energy remains same through the motion as P.E converts to K.E and K.E converts to P.E.

• A. 0o
• B. 60°
• C. 90°
• D. 23°

Explanation: We are given:P = 2500 WF = 500 Nv = 10 m/sWe can rearrange the formula to solve forcos theta=P/F.vcos theta = 2500/500×10 cos theta…

• A. 2 s
• B. 4 s
• C. 86 s
• D. 16 s

Explanation: First, we need to calculate the work done (W) to lift the mass. The work done is equal to the change in gravitational potential energy…

• A. 25 ms-1
• B. 4.0 ms-1
• C. 2.5 ms-1
• D. 40 ms-1

Explanation: P is the power in watts.F is the force in newtons.v is the speed in meters per second.We are given:P = 24 kW = 24 × 1000 = 24000 WF = 600…

• A. 3 J
• B. 120 J
• C. 720 J
• D. 430 J

Explanation: To find the energy (E) given out by the lamp, we use the formula:E = P twhere P is power and t is time.Given:P = 6 Wt = 2 minutes = 2×60 =…

• A. 1
• B. 4/3
• C. 16/9
• D. None of these

Explanation: W = 80Nm = 80 / gt = 15 secP = W / t = mgh / t1st manW = mgh= 80 × 9.8 × h= 784 hPower₁ = 784 h / 15m₂ = 80 kgSame heightt = 20 sW = 80 ×…

• A. 44%
• B. 55%
• C. 66%
• D. 77%

Explanation: 2(n) + n² / 100 %Put n = 202(20) + (20)² / 100 %40 + 400 / 100 %40 + 4 = 44 %So 44% is your answer.

• A. Become twice its initial value
• B. Become three time, its initial value
• C. Become four time, its initial value
• D. Remains constant

Explanation: K.Ef= 4 K.Ei=> pf² / 2m = 4 (pi² / 2m)=> pf² = 4 pi²=> pf² = 2 pi²The new momentum will be two times the initial momentum.