Question

What is the kinetic energy of an object with a mass of `5 kg` that has been in freefall for `8 s`?

Answer 1

`15.366kJ`

Explanation:

Assuming the object has fallen from rest near earth, we may use the equations of motion for constant acceleration to find its velocity after 8 seconds :

`v=u+at`

`=0+(9,8)(8)`

`=78,4m//s`

Hence its kinetic energy at this stage is

`E_k=1/2mv^2`

`=1/2xx5xx78.4^2`

`=15,366kJ`