A boy of mass 50 kg runs up a staircase of 40 steps in 10 s. If the height of each step is 15 cm, find his power. Take \(g = 10 \text{ ms}^{-2}\).
300 W
Total height climbed h = 40 × 0.15 = 6 m. Work done against gravity W = mgh = 50 × 10 × 6 = 3000 J. Power = work / time = 3000 / 10 = 300 W. Note the unit — power is Watt (J/s), not Joule. Hence the power is 300 W, matching option 2.
Similar Questions
A device uses 1 kilowatt (kW) of power for 1 hour. How much energy does it consume?
Student A takes 20 seconds, while student B takes 40 seconds to complete the same amount of work. Which of the following statements is correct in connection to A and B?
If a girl of weight 40 N climbs a rope with a power of 160 W for 20 seconds, up to what height can she reach?
A boy of mass 50 kg runs up a staircase of 40 steps in 10 s. If the height of each step is 15 cm, find his power. Take \(g = 10 \text{ ms}^{-2}\).
A boy of mass 50 kg climbs 43 steps in 10 s. If each step is 15 cm high, find his power. Take \(g = 10 \text{ ms}^{-2}\).
A 100 W electric bulb is used for 8 hours a day. The energy used by the bulb in 5 days is _____ units.
A boy of mass 50 kg climbs 42 steps in 10 s. If each step is 15 cm high, find his power. Take \(g = 10\text{ms}^{-2}\).
What is the SI unit of Power?
A factory manager is comparing two machines that perform the same task. Machine A takes more time to complete the task than Machine B. Based on the definition of power, which factor should the manager consider to determine which machine is more powerful?
Rate of doing work is called ________.
Important Questions from Power
Express the power dissipated in a 100 Ω resistor in dB relative to 1 mW, when the voltage across the resistor is 1.0 Vrms
An elevator weighing 500 kg is to be lifted up at a constant velocity of 0.25 m/s. What would be the minimum horsepower of the motor to be used? G = 9.8 m/s2 and there is no frictional loss.
A man of mass 80 kg climbs up 4 m high stairs in 10 sec. Find the power spent by the man. (Take g = 10 m/sec2)
How many units of electric power will be consumed by 4 motors of 0.5 HP each in 8 hours?
The power of a water pump is 2 kW. The amount of water (in litres) it can raise in one minute to a height of 10 m will be :
(g = 10 m/s 2 )
