Advertisements
Advertisements
प्रश्न
A person holds a bundle of hay over his head for 30 minutes and gets tired. Has he done some work or not? Justify your answer.
Advertisements
उत्तर
Work is done whenever the given two conditions are satisfied:
- A force acts on the body.
- There is a body displacement by applying force in or opposite to the direction of force.
- A person holding a bundle of hay on his head becomes exhausted due to muscular weariness. This tiredness is caused by converting chemical energy into heat energy via muscular effort. The guy has done no work because his exertion does not cause the bundle over his head to move, i.e., s = 0.
APPEARS IN
संबंधित प्रश्न
What is power?
A battery lights a bulb. Describe the energy changes involved in the process.
Find the energy in joules consumed in 10 hours by four devices of power 500 W each.
How much is the mass of a man if he has to do 2500 joules of work in climbing a tree 5 m tall? (g = 10 m s−2)
What is the power of a body which is doing work at the rate of one joule per second?
Fill in the blank with suitable word :
Power is the rate of doing ___________.
The power output of an engine is 3kW. How much work does the engine do in 20 s?
A car of weight 20000 N climbs up a hill at a steady speed of 8 m/s, gaining a height of 120 m is 100 s. Calculate : power of engine of car.
Define power. Give the SI unit of power.
A boy weighing 40 kg carries a box weighing 20 kg to the top of a building 15 m high in 25 seconds. Calculate the power. (g = 10 m/s2)
