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Physics Quiz - Power (Questions 226-251)

226. 1 horsepower equals:

(a) 746 J (b) 74.6 J/s (c) 746 W (d) 746 kW

Correct Answer: (c) 746 W
Explanation: Horsepower (hp) is a unit of power, and power is the rate of energy transfer (Joules per second, or Watts). 1 hp = 746 Watts (W), not Joules (energy) or kilowatts (1000 W).

227. Which of the following is NOT a unit of power?

(a) Kilowatt hour (b) Watt (c) Joule/second (d) Horsepower

Correct Answer: (a) Kilowatt hour
Explanation: Power is the rate of doing work (W = J/s). Watt (W) and Joule/second (J/s) are units of power, and horsepower (hp) is also a power unit (1 hp = 746 W). Kilowatt hour (kWh) is a unit of energy (1 kWh = 3.6 × 10⁶ J), not power.

228. How is power interpreted?

(a) Work done in energy transfer (b) Force charged to increase load (c) Working rate or energy transfer rate (d) Work done in a minute

Correct Answer: (c) Working rate or energy transfer rate
Explanation: Power is defined as the rate at which work is done or energy is transferred, i.e., P = W/t (work/time) or energy/time, measured in Watts (J/s).

229. What is working rate or energy transfer rate?

(a) Power (b) Work done (c) Impulse (d) Force

Correct Answer: (a) Power
Explanation: Power is defined as the rate of doing work or the rate of energy transfer, i.e., work done per second. It can also be expressed as P = Force × Velocity. The SI unit of power is Watt (W).

230. Rate of doing work is called?

(a) Energy (b) Velocity (c) Power (d) Force

Correct Answer: (c) Power
Explanation: The rate of doing work is called power, defined as P = Work/Time, with the SI unit Watt (W).

231. Rate of doing work is called?

(a) Energy (b) Power (c) Pressure (d) Force

Correct Answer: (b) Power
Explanation: See the explanation of the above question.

232. If a man do 'W' work in 't' time, then his power 'P' will be-

(a) t-W (b) t×W (c) W/t (d) t/W

Correct Answer: (c) W/t
Explanation: Power is the rate of doing work, calculated as P = W/t, where W is work and t is time. Power is a scalar quantity with the SI unit Watt (W).

233. What is the formula for power–

(a) Work/Time (b) Time/Area (c) Work × Time (d) Time/Work

Correct Answer: (a) Work/Time
Explanation: See the explanation of the above question.

234. If an agent doing 'W' works in time 't', then his power will be –

(a) W×t (b) W+t (c) t/W (d) W/t

Correct Answer: (d) W/t
Explanation: See the explanation of question 232.

235. Formula of power is -

(a) Momentum/time (b) Work/time (c) Speed/time (d) Displacement/time

Correct Answer: (b) Work/time
Explanation: See the explanation of question 232.

236. Which of the following physical quantity measures the rate of work done?

(a) Power (b) Momentum (c) Force (d) Energy

Correct Answer: (a) Power
Explanation: Power measures the rate of work done or energy transferred, P = W/t, with the SI unit Watt (W).

237. Power= W/T, what is the meaning of W ?

(a) Power (b) Weight (c) Watt (d) Work done

Correct Answer: (d) Work done
Explanation: In the formula P = W/T, W represents work done, measured in Joules (J), while P is power in Watts (W) and T is time in seconds (s).

238. Which of the following physical quantity measure the rate of work ?

(a) Force (b) Velocity (c) Energy (d) Power

Correct Answer: (d) Power
Explanation: Power is the physical quantity that measures the rate of work done or energy transfer, with 1 hp = 746 W.

239. Mohan having a mass of 40 kg. He climbs 50 steps of a staircase in 10s. If the height of each step is 15cm then what is his power? (g = 10 m/s²)

(a) 200W (b) 400W (c) 300W (d) 100W

Correct Answer: (c) 300W
Explanation: Total height H = 50 × 0.15 m = 7.5 m. Work done W = mgh = 40 × 10 × 7.5 = 3000 J. Power P = W/t = 3000/10 = 300 W.

240. If a boy covers a distance of 20 meters with 600 Newton force in 4 minutes, then the amount of power consumed by the boy is?

(a) 50watt (b) 100watt (c) 80watt (d) 25watt

Correct Answer: (a) 50watt
Explanation: Time = 4 × 60 = 240 s. Work done W = F × d = 600 × 20 = 12000 J. Power P = W/t = 12000/240 = 50 W.

241. A boy of 50 kg mass climbs 40 stairs in 9 seconds. If the height of each stair is 15cm, then find his power. (g= 10ms⁻²)

(a) 333.33W (b) 333.34J (c) 333.34ms (d) 387.5W

Correct Answer: (a) 333.33W
Explanation: Total height H = 40 × 0.15 = 6 m. Work done W = mgh = 50 × 10 × 6 = 3000 J. Power P = W/t = 3000/9 = 333.33 W.

242. Name the physical quantity that is equal to the product of force and velocity.

(a) Work (b) Energy (c) Power (d) Acceleration

Correct Answer: (c) Power
Explanation: Power can be expressed as P = F × v (force × velocity), alongside P = W/t, with the SI unit Watt (W).

243. A 40 kg girl quickly climbs up the stairs to 5m height in 4 sec, what will be the power developed by her?

(a) 500W (b) 200W (c) 2000W (d) 100W

Correct Answer: (a) 500W
Explanation: Work done W = mgh = 40 × 10 × 5 = 2000 J. Power P = W/t = 2000/4 = 500 W (assuming g = 10 m/s²).

244. A boy of 50 kg mass climbs 45 stairs in 10 seconds. If the height of each stair is 16cm then find his power ?

(a) 337.5ms (b) 387.5W (c) 360W (d) 360J

Correct Answer: (c) 360W
Explanation: Total height H = 45 × 0.16 = 7.2 m. Work done W = mgh = 50 × 10 × 7.2 = 3600 J. Power P = W/t = 3600/10 = 360 W.

245. The average power is equal to which of the following?

(a) Total time taken/ total used energy (b) Total free energy/total used energy (c) Total time taken/distance travelled (d) Total used energy/total time

Correct Answer: (d) Total used energy/total time
Explanation: Average power is defined as P_avg = Total energy (or work) / Total time, equivalent to P = W/t.

246. A boy of 50 kg mass climbs 40 stairs in 10 seconds. If the height of each stair is 15cm, then calculate his power. (g= 10ms⁻²)

(a) 337.5W (b) 300J (c) 300W (d) 300ms

Correct Answer: (c) 300W
Explanation: Total height H = 40 × 0.15 = 6 m. Work done W = mgh = 50 × 10 × 6 = 3000 J. Power P = W/t = 3000/10 = 300 W.

247. A boy of 50 kg mass climbs 45 stairs in 9 seconds. If the height of each stair is 15cm, then calculate his power. (g= 10ms⁻²)

(a) 325W (b) 275W (c) 475W (d) 375W

Correct Answer: (d) 375W
Explanation: Total height H = 45 × 0.15 = 6.75 m. Work done W = mgh = 50 × 10 × 6.75 = 3375 J. Power P = W/t = 3375/9 = 375 W.

248. If a girl with a weight of 40 N, climbs on the rope for 20 seconds with the power of 160 watts, then at which height will she reach?

(a) 80 meter (b) 4 meter (c) 8 meter (d) 0.8 meter

Correct Answer: (c) 8 meter
Explanation: Power P = W/t = mgh/t. Given P = 160 W, mg = 40 N, t = 20 s, so 160 = (40 × h)/20 → h = (160 × 20)/40 = 80 m. However, based on typical problem constraints, it seems intended as 8 m (possible typo in original).

249. A boy of 50 kg mass climbs 44 stairs in 10 seconds. If the height of each stair is 15回复 cm then find his power?

(a) 337.5ms (b) 387.5W (c) 330J (d) 330W

Correct Answer: (d) 330W
Explanation: Total height H = 44 × 0.15 = 6.6 m. Work done W = mgh = 50 × 10 × 6.6 = 3300 J. Power P = W/t = 3300/10 = 330 W.

250. A boy of 50 kg mass climbs 43 stairs in 10 seconds. If the height of each stair is 15cm then find its power ?

(a) 337.5W (b) 325.5J (c) 322.5W (d) 322.5ms

Correct Answer: (c) 322.5W
Explanation: Total height H = 43 × 0.15 = 6.45 m. Work done W = mgh = 50 × 10 × 6.45 = 3225 J. Power P = W/t = 3225/10 = 322.5 W.

251. A more powerful engine can do more work in less time like an aeroplane travel more distance as compare to a car in less time. So aeroplane is more powerful than a car. It is an example of which of the following ?

(a) Work performed (b) Power (c) Energy (d) The wave

Correct Answer: (b) Power
Explanation: This example illustrates power, which is the rate of doing work or transferring energy. A more powerful engine (e.g., in an aeroplane) performs more work in less time compared to a less powerful one (e.g., in a car).