Applying Newton's Third Law of Mortion

[Rosieposy08]

Homework Statement

After falling from a rest from a height of 30 m, a .50 kg ball rebounds upward, reaching a height of 20 m. If the contact between ball and ground lasted 2.0 ms, what average force was exerted on the ball?

Homework Equations

2.0ms=.002s

The Attempt at a Solution

 

[leachlife4]

Consider the total energy and direction (and change thereof) the ball has before and after the impact.

 

[supratim1]

hello Rosieposy! Welcome to physics forums!

you need to show your attempt at solving the question, if you are stuck people here will help you.

 

[ashishsinghal]

Use impulse = change in momentum.
BTW how is this an application of Newton's Third Law of Motion. As I recall it was action reaction law. You are not considering the force exerted on the ground by the ball, are you?