Question

What is the kinetic energy of an object with a mass of `3` `kg` that has been in freefall for `9` `s`?

Answer 1

First step is to calculate the velocity, `v=u+at=0+9.8*9=88.2` `ms^-1`.

Second step is to use this to calculate the kinetic energy, `E_k=1/2mv^2=1/2*3*88.2^2=11669` `J=11.7` `kJ`.

Explanation:

The initial velocity, `u` can be assumed to be `0` `ms^-1` if we are not told otherwise, and the acceleration is just the acceleration due to gravity, `9.8` `ms^-2`.

The kinetic energy is a function of the mass and velocity of the object.