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 18 of 38
- A. 20 J
- B. 5 J
- C. 10 J
- D. 0 J
Explanation: Net force = ma = 2×5 = 10 N. Work = F d = 10×2 = 20 J. Thus option A is correct.
Correct answer: 20 J- A. 324 J
- B. 486 J
- C. 256 J
- D. 524 J
Explanation: Momentum conservation: 0 = 18×6 + 12 v ⇒ v = −9 m/s. KE of 12 kg = ½×12×9² = 486 J. So option B is correct.
Correct answer: 486 J- A. Frictional force
- B. Gravitational force
- C. Earth's magnetic force
- D. Nuclear force
Explanation: The gravitational forces exerted by the Moon and the Sun are the primary cause of ocean tides.
Correct answer: Gravitational force- A. 50 J
- B. 150 J
- C. 100 J
- D. 200 J
Explanation: Horizontal displacement does no work (force vertical component does no work horizontally if force vertical).
Correct answer: 100 J- A. Po / Po+ PL
- B. PL / Po
- C. PL/ Pi
- D. Po / Pi
Explanation: Power transferred through a machine; input power = Pi ; output power =PO ; Power loss=PL .
Correct answer: Po / Po+ PL- A. 10 J
- B. 90J
- C. 270J
- D. 180J
Explanation: KE ∝ v². Speed increases by factor 3, so KE increases by 3² = 9 times: 30×9 = 270 J. Hence option C.
Correct answer: 270J- A. m⁰
- B. m²
- C. m
- D. m¹/²
Explanation: With constant force F, acceleration a = F/m; final v² ∝ (F/m) s, so KE = ½ m v² ∝ m × (F/m) s = F s, independent of m in that expression.
Correct answer: m- A. mgh
- B. mgh/p
- C. gh
- D. pgh
Explanation: Potential energy per unit volume = (mgh) / volume = (ρVgh)/V = ρ g h (where ρ is density p). So option D (pgh) is correct.
Correct answer: pgh- A. Doubled
- B. Halved
- C. Four times
- D. Same
Explanation: KE = p²/(2m); if p doubles, KE increases by factor 2² = 4. Hence KE becomes four times, option C.
Correct answer: Four times- A. mgh
- B. Zero
- C. 1/2 mv²
- D. 2 mgh
Explanation: At maximum height vertical speed is zero so KE = 0; total energy equals potential energy mgh.
Correct answer: mgh- A. 100 m
- B. 10 m
- C. 50 m
- D. 5 m
Explanation: Using ½ v² = g h ⇒ h = v²/(2 g) = 100/(2×9.8) ≈ 5.10 m ≈ 5 m. So option D is correct.
Correct answer: 5 m- A. Be negligible
- B. Be maximum
- C. Be zero
- D. Not be predicted
Explanation: If mgh = ½ m v² without additional terms, no energy is lost to friction; thus frictional work fh = 0, implying negligible or zero air…
Correct answer: Be zero- A. 0°
- B. 60°
- C. 90°
- D. 23°
Explanation: P = F v cosθ ⇒ cosθ = P/(F v) = 2500/(500×10) = 0.5 ⇒ θ = 60°. Thus option B is correct.
Correct answer: 60°- A. 25 ms⁻¹
- B. 4.0 ms⁻¹
- C. 2.5 ms⁻¹
- D. 40 ms⁻¹
Explanation: v = P/F = 24000 W / 600 N = 40 m/s. Hence option D is correct.
Correct answer: 40 ms⁻¹- A. 33 kW
- B. 3.3 kW
- C. 0.33 kW
- D. 0.033 kW
Explanation: Useful power = m g h / t = 100×10×10 /5 = 2000 W. Input power = useful / 0.6 ≈ 3333 W = 3.333 kW ≈ 3.3 kW.
Correct answer: 3.3 kW- A. 1.2 kW
- B. 12 kW
- C. 120 kW
- D. 1200 kW
Explanation: Power = rate of change of mechanical energy; here P = ṁ × (½ v² + g h); if interpreted as lifting to give exit kinetic energy only, use P…
Correct answer: 1.2 kW- A. 30.6 ms⁻¹
- B. 3.06 ms⁻¹
- C. 0.306 ms⁻1
- D. 300.6 ms⁻¹
Explanation: v = P/(m g) = 3000/(1000×9.8) ≈ 0.306 m/s. Thus option C is correct.
Correct answer: 0.306 ms⁻1- A. 2.45 watt
- B. 245 watt
- C. 24.5 watt
- D. 2.45 Kwatt
Explanation: m = 5 kg, power = m g h / t = 5×9.8×1 /2 = 24.5 W. So option C is correct.
Correct answer: 24.5 watt- A. 120 J
- B. 60 J
- C. 30 J
- D. 0.02 J
Explanation: Given:Power = P = 60 wattTime = t = 2 secondsEnergy = E = ?To determine the consumption of energy, we can use theformula:E = P × tE = 60 ×…
Correct answer: 120 J- A. 50 J
- B. 75 J
- C. 100 J
- D. 150 J
Explanation: Work = F d cosθ = 15×10×cos60° = 150×0.5 = 75 J. So option B is correct.
Correct answer: 75 J