**Power Quiz and Answers **are must for the aspirants who are preparing for various competitive examination. It covers the concept of Work, Energy and Power which is very important for any competitive exams. This Law of Work, Energy and Power topic is given most importance in various competitive exams like JEE Main, JEE Advanced, NEET, AIIMS etc.

## Power Quiz and Answers

**1. A motor is used to pump water from a depth of 5 m to fill a volume of 10 cubic meters in 5 minutes. If 50% of the power is wasted, what is the power of the motor? (Assume g = 10m/s**^{2}**)**

^{2}

a) 1000/3 W

b) 3000/3 W

c) 5000/3 W

d) 10000/3 W

**Answer****:** d

**2. A machine has a power of 20kW. How long will it take for it to lift a body of mass 10kg from the ground to a height of 100m? (Assume g = 10m/s**^{2}**)**

^{2}

a) 1 second

b) 2 seconds

c) 3 seconds

d) 4 seconds

**Answer**: b

**3****. A 2-ton vehicle travels at 20m/s on a road where the frictional force is 10% of the weight of the vehicle. What is the power required? (Assume g = 10m/s**^{2}**)**

^{2}

a) 220 kW

b) 240 kW

c) 420 kW

d) 440 kW

**Answer**: d

**4. 1000 kW of power is supplied to a motor. 90% of this is transmitted to a machine operating at 80% efficiency. The machine lifts an object of 10-tons with a velocity _____ m/s. (Assume g = 10m/s**^{2}**)**

^{2}

a) 2

b) 4

c) 6

d) 8

**Answer**: c

**5. A 200 kg wagon climbs up a hill of slope 30-degrees in 1 minute at a speed of 10 m/s. How much power is delivered by the engine? (Assume g = 10m/s**^{2}**)**

^{2}

a) 10 kW

b) 20 kW

c) 30 kW

d) 40 kW

**Answer**: b

**6. A body of mass 3 kg starts from rest with a uniform acceleration of unknown magnitude. If the body has a velocity of 30 m/s in 6 seconds, what is the power consumed in 3**** seconds?**

a) 125 W

b) 225 W

c) 325 W

d) 425 W

**Answer****:** b

**7. The force required to tow a vehicle at constant velocity is directly proportional to the magnitude of velocity raised to the first power. It requires 1000 W to tow with a velocity of 10 m/s. How much power is required**** to tow at a velocity of 8 m/s?**

a) 320 W

b) 640 W

c) 160 W

d) 80 W

**Answer**: b

**8. What are the units of power?**

a) Newton

b) Joule

c) Watt

d) No units

**Answer: **c

**9. A machine gun fires 360 bullets per minute. Each bullet has a mass of 5 grams and travels at 600 m/s. What is the power of the gun? (Assume no loss of energy and 100% power transmission)**

a) 300 W

b) 600 W

c) 900 W

d) 1800 W

**Answer: **c

**10. A motor is used to deliver water through a pipe. Let the motor have a power P initially. To double the rate of flow of water through the pipe, the power is increased to P’. What is the value of P’/P?**

a) 2

b) 4

c) 6

d) 8

**Answer: **d