An object of mass 40 kg is raised to a height of 5 m above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down.

Asked by Vishal kumar | 1 year ago |  183

##### Solution :-

Given Mass (m) = 40 kg

Acceleration due to gravity = (g) = 10 m/s2

Height (h) = 5 m

Potential energy = $$m\, \times\,g\,\times\,h$$

P.E = $$40\,\times\,10\,\times\,5\,=\,200J$$

potential energy = 2000 J (2000 joules)

At a height of 5 metre, the object has a potential energy of 2000 J.

When this object is allowed to fall, and it is Halfway down its height above the ground will be half of 5 m = $$5\,m=\,\frac{5}{2}=\,2.5\,m$$

P.E at Halfway down = $$m\, \times\,g\,\times\,h$$

P.E = $$40\,\times\,10\,\times\,2.5\,=\,1000J$$

{h =2.5 m}

Potential Energy at halfway down = 1000 joules

According to law of conservation of energy

Total potential energy = potential energy at Halfway down + kinetic energy at Halfway of a down 2000 = 1000 + K.E at Halfway down

K.E at Half down = 2000 - 1000 = 1000 J

Kinetic energy at halfway down = 1000 joules.

Answered by Shivani Kumari | 1 year ago

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