1. A boy is standing on top of a roof that is 4.5 m high. If he throws a 1.4 kg water balloon down with a velocity of 2m/s, what velocity will the water balloon strike the ground with? (ignore air resistance)

The magnitude of the final velocity of the water balloon is 84.3 m/s.

Explanation:

To calculate the velocity of the water balloon when it strikes the ground we need to use the next equation:

Where:

: is the final velocity =?

: is the initial velocity = 2 m/s

g: is the gravity = 9.81 m/s²

h: is the height = 4.5 m

By entering the above values into equation (1) we have:

The minus sign is because the direction of the velocity vector is in the negative vertical axis.  

Therefore, the magnitude of the final velocity of the water balloon is 84.3 m/s.

I hope it helps you!