Advertisements
Advertisements
Question
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)
Advertisements
Solution
Work done in climbing or potential energy, (P.E) = 2500 J
Acceleration due to gravity, (g) = 10 m/s2
Height above the ground be, (h) = 5 m
Let the mass of the man be (m)
We have a relation as,
P.E = m × g × h
So, mass can be calculated as,
`m = (P.E)/(h xx g)`
so , mass of the man ,
`m = 2500/(5 xx 10)` kg
= `250/5` kg
= 50 kg
APPEARS IN
RELATED QUESTIONS
What is power?
A lamp consumes 1000 J of electrical energy in 10 s. What is its power?
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.
Find the energy in joules consumed in 10 hours by four devices of power 500 W each.
A load of 100 kg is pulled up by 5 m. Calculate the work done. (g = 9.8 m/s2)
Define kilowatt-hour.
A man weighing 500 N carried a load of 100 N up a flight of stairs 4 m high in 5 seconds. What is the power?
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 : work done by the car.
In loading a truck, a man lifts boxes of 100 N each through a height of 1.5 m.
If the man lifts 4 boxes per minute, at what power is he working?
(g = 10 m s−2)
Which one of the following statements about power stations is not true?
