Answer:
Acceleration, 
Explanation:
Given that,
Height from a ball falls the ground, h = 17.3 m
It is in contact with the ground for 24.0 ms before stopping.
We need to find the average acceleration the ball during the time it is in contact with the ground.
Firstly, find the velocity when it reached the ground. So,

u = initial velocity=0 m/s
a = acceleration=g

It is in negative direction, u = -18.41 m/s
Let a is average acceleration of the ball. Consider, v = and u = -18.41 m/s.

So, the average acceleration of the ball during the time it is in contact is
.
There are two ways to solve this problem. First we write the given.
Given: Force F = 400 N; Height h = 0.5 m; Time t = 2 s
Formula: P = W/t; but Work W = Force x distance or W = f x d
Weight is also a Force, therefore: W = mg, solve for Mass m = ?
m = w/g m = 400 N/9.8 m/s² m = 40.82 Kg
P = W/t = F x d/t = mgh/t P = (40.82 Kg)(9.8 m/s²)/2 s
P = 100 J/s or 100 Watts
The correct answer is b changing tides