What is its speed when it hits the ground?

Question

A student drops a water balloon out of a dorm window 11 m above the ground. What is its speed when it hits the ground?

Answer 1

We can find the speed of the water balloon when it hits the ground from the law of conservation of energy (the potential energy of the water balloon at the height of 11m above the ground becomes the kinetic energy at ground level):

Potential Energy =Kinetic Energy

PE=KE

mgh=1/2mv² the mass can cancel out

gh=1/2v² where g=9.81m/s²

v=√2gh

=√2*9.81m/s²*11m

= 14.7 m/s