# What is the kinetic energy of an object with a mass of 15 kg that has been in freefall for 3 s?

The kinetic energy is $\mathrm{dK} = \frac{1}{2} m {\left(a t\right)}^{2} = 6496 J$
You find the final speed on the object $v = a t$
and consider the equation $\mathrm{dK} = \frac{1}{2} m {v}^{2} = 6496 J$