Free Power MCQs with Answers

• A. the total work done
• B. the rate of doing work
• C. work done times time taken
• D. force times displacement

Explanation: Power is work done per unit time, measured in watts, where one watt is one joule per second.

• A. 100 W
• B. 1000 W
• C. 2000 W
• D. 20000 W

Explanation: The work done is mgh, which is 200 times 10 times 10, giving 20000 J. Dividing by the 20 s taken gives 1000 W, or 1 kW.

• A. the total work done
• B. the rate at which work is done or energy is transferred
• C. the force multiplied by the distance
• D. the energy stored in a body

Explanation: One watt is one joule per second, so power tells you how quickly energy is delivered rather than how much.

• A. 500 W
• B. 1000 W
• C. 200 W
• D. 10000 W

Explanation: The work done is mgh, that is 100 multiplied by 10 multiplied by 10, giving 10,000 J, and dividing by 20 seconds gives 500 W.

• A. watt
• B. Joule
• C. Newton
• D. Pascal

Explanation: Power is the rate of doing work or transferring energy, P = W/t, and its SI unit is the watt (W).

• A. Force and time
• B. Force and velocity
• C. Force and speed
• D. None of these

Explanation: Mechanical power is the rate of doing work: P = F · v = Fv cosθ, so it is the dot product of force and velocity.

• A. displacement
• B. acceleration
• C. power
• D. energy

Explanation: Power is the rate at which work is done, P = W/t. Therefore, the slope of a work-time graph, ΔW/Δt, is power and is measured in watts.

• A. 1 hp = 546 watts
• B. 1 hp = 746 watts
• C. 1 hp = 1000 watts
• D. 1 hp = 946 watts

Explanation: The mechanical horsepower is defined as approximately 746 W. Thus 1 hp = 746 watts, where a watt is 1 J/s.

• A. power
• B. work
• C. impulse
• D. torque

Explanation: Instantaneous power is the dot product of force and velocity: P = F · v, measured in watts.

• A. [ML2T-3]
• B. [ML2T-2]
• C. [ML2T3]
• D. none of these

Explanation: Power is work divided by time. Since work has dimensions [M L2 T-2], power has dimensions [M L2 T-2]/T = [M L2 T-3], which is option a.

• A. 120 J
• B. 60 J
• C. 30 J
• D. 0.02 J

Explanation: Power is the rate of energy consumption, so energy = power x time = 60 W x 2 s = 120 J.

• A. any rate
• B. at variable rate
• C. at uniform rate
• D. at high rate

Explanation: Average power is total work divided by total time, while instantaneous power is the rate of doing work at a particular instant.

• A. IRt
• B. I2R
• C. I2Rt
• D. VIt

Explanation: The rate at which electrical energy is converted into heat is electrical power, P = I²R, measured in watts (W).

• A. watt
• B. horse power
• C. kilo watt
• D. kilowatt hour

Explanation: Electrical energy used by homes and appliances is commonly measured in kilowatt-hours (kWh), where 1 kWh = 1000 W used for 1 hour.

• A. 12
• B. 24
• C. 5
• D. 1100

Explanation: The energy consumed is E = Pt = 500 W x 24 h = 12000 Wh = 12 kWh, so the answer is 12 units of electrical energy.

• A. 144000J
• B. 144J
• C. 1.44J
• D. 14J

Explanation: Electrical energy is calculated from E = Pt: 40 W x 1 h x 3600 s/h = 144000 J.

• A. one second
• B. one day
• C. one minute
• D. one hour

Explanation: One kilowatt-hour is the energy supplied by a power of 1 kilowatt operating for 1 hour, so the time interval is one hour.

• A. more heat is produced in thick wire
• B. more heat is produced in thin wire
• C. no heat is produced in wire
• D. less heat is produced in thick wire

Explanation: For the same current and time, heat produced is H = I²Rt. A thin wire of the same material and length has greater resistance because its…

• A. 1260 W
• B. 12.6 kW
• C. 210 W
• D. 12.6 W

Explanation: To find : the power of the heater if the specific heat capacity of water is 4.2 J/g/C is..solution : first we should find the energy…

• A. 3000 N
• B. 30000 N
• C. 300000 N
• D. 300 N

Explanation: To find the pushing force exerted by the motorbike engine, we can use the equation: Power = Force × Velocity (P = W/T = Fd/T = Fv as d/T…