Advertisements
Advertisements
Question
A weightlifter is lifting weights of mass 200 kg up to a height of 2 metres. If g = 9.8 m s−2, calculate :
potential energy acquired by the weights.
Advertisements
Solution
Mass of the weights, (m) = 200 kg
Acceleration due to gravity, (g) = 9.8 m/s2
Height above the ground, (h) = 2 m
We can calculate potential energy as,
F.E = m × g × h
So,
`P.E = 200 xx 9.8 xx 2 "J"`
= 3920 J
APPEARS IN
RELATED QUESTIONS
A body of mass m is moved from ground to a height h. If the force of gravity on mass of 1 kg is g newton, find the force needed to lift the body.
The gravitational potential energy stored in a box of weight 150 kgf is 1.5 × 104 J. Find the height of the box. Take 1 kgf = 10 N.
A body falls freely under gravity from rest. Name the kind of energy it will possess at the point from where it falls.
Is potential energy a vector or a scalar quantity?
A boy weighing 50 kg climbs up a vertical height of 100 m. Calculate the amount of work done by him. How much potential energy does he gain? (g = 9.8 m/s2)
To what height should a box of mass 150 kg be lifted, so that its potential energy may become 7350 joules? (g = 9.8 m/s2)
Give one example each of a body possessing : (i) kinetic energy, and (ii) potential energy.
Explain by an example what is meant by potential energy. Write down the expression for gravitational potential energy of a body of mass m placed at a height h above the surface of the earth.
If 784 J of work was done in lifting a 20 kg mass, calculate the height through which it was lifted. (g = 9.8 m/s2)
If we increase the velocity of a car moving on a flat surface to four times its original speed, its potential energy ______.
