A man of power 558W threw a
cricket ball of mass 300g to the upward direction with a
velocity 40m/s.
At what height the potential and kinetic energy of
the ball will be same? Calculate it
Answers
Answer:
The 300 gram (0.300 kg) ball travels vertically at 40 m/s. Its kinetic energy
Ek initially is:
Kinetic Energy =1/2^2
Kinetic Energy = 1/2 x 0.300 x 40^2
=240 joules
In the absence of air friction, all of this kinetic energy will be converted to potential energy. So Gain of Gravitational Potential Energy (GPE) = Loss of Kinetic Energy (KE).
GPE = mass (m) x gravity (g) x height (g)
GPE = KE
Mass x gravity x height = Kinetic energy
Mass x gravity x height = 240 Joules (from above)
Rearrange the equation mgh = 240 so that h is the subject
height = 240 ÷ (mass x gravity)
height = 240 ÷ (0.3 x 10)
height = 80 metres
Potential energy is directly proportional to height, so when half of the initial kinetic energy has been converted to potential energy, the ball is at half of its maximum height. At that height, the potential and kinetic energy will be equal.
Half of 80 metres = 40 metres
Final answer= 40 metres
Explanation: Hope this helps :)