Power — NEET Physics MCQs with Solutions
Free NEET Physics Power MCQs with step-by-step solutions (8 questions). Part of Work, Power and Energy. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Power · easy · theory
Instantaneous power delivered by a force F⃗ to a body moving with velocity v⃗ is:
A. P = F⃗ × v⃗
B. P = F⃗·v⃗ ✓ Correct
C. P = F/v
D. P = Fv always (any angle)
Solution: P = F⃗·v⃗ = Fv cosθ. It is a scalar; 1 W = 1 J/s and 1 hp ≈ 746 W.
Q2 — Power · medium · theory
A machine delivers constant POWER to a body. The work done by it in time t is:
A. W = Pt (grows linearly with time) ✓ Correct
B. W = P/t
C. W = ½Pt²
D. Constant, independent of t
Solution: P = dW/dt constant ⇒ W = Pt. (The body's speed then grows as √t.)
Q3 — Power · easy · numerical
A motor lifts a 100 kg load through 3 m in 10 s at constant speed. The power delivered is:
A. 1000 W
B. 30 W
C. 3000 W
D. 300 W ✓ Correct
Solution: P = mgh/t = 100×10×3/10 = 300 W.
Q4 — Power · medium · numerical
A car moves at a constant 20 m/s against a total resistance of 500 N. The power developed by the engine is:
A. 25 kW
B. 100 kW
C. 2.5 kW
D. 10 kW ✓ Correct
Solution: Constant speed ⇒ drive force = resistance. P = Fv = 500×20 = 10⁴ W = 10 kW.
Q5 — Power · hard · numerical
A pump raises 200 kg of water per minute to a height of 10 m and ejects it at 2 m/s. The power required is:
A. ≈ 333 W
B. ≈ 3400 W
C. ≈ 400 W
D. ≈ 340 W ✓ Correct
Solution: Per minute: mgh + ½mv² = 20000 + ½×200×4 = 20400 J. P = 20400/60 = 340 W. Trap: don't forget the kinetic-energy term.
Q6 — Power · medium · numerical
A machine gun fires 60 bullets per minute, each of mass 10 g at 600 m/s. The power delivered to the bullets is:
A. 3600 W
B. 1080 W
C. 1800 W ✓ Correct
D. 600 W
Solution: One bullet: ½×0.01×360000 = 1800 J; 60 per minute = 1 per second ⇒ P = 1800 W.
Q7 — Power · easy · numerical
A 60 kg person climbs stairs of total height 3 m in 6 s. The average power developed is:
A. 30 W
B. 300 W ✓ Correct
C. 600 W
D. 180 W
Solution: P = mgh/t = 60×10×3/6 = 300 W.
Q8 — Power · medium · numerical
A 2 kW motor pump lifts water to a height of 20 m. The mass of water raised per second is:
A. 2 kg
B. 100 kg
C. 20 kg
D. 10 kg ✓ Correct
Solution: P = (dm/dt)gh ⇒ dm/dt = 2000/(10×20) = 10 kg/s.