Question

A ball is dropped from a window and takes 2 seconds to reach the ground. It starts from rest and reaches a final speed of 20 m/s. what is the ball's acceleration?

Answer 1

The answer is 40 m, because you must cross multiply by using proportions.
I showed my work below.

Answer 2

The acceleration of the ball is 10
`m/s^2 .`

To find the acceleration of the ball, you can use the following kinematic equation:

v=u+at

where:

v is the final velocity,

u is the initial velocity,

a is the acceleration,

t is the time.

The ball starts from rest, so the initial velocity (u) is 0 m/s. The final velocity (v) is 20 m/s, and the time (t) is 2 seconds.

20=0+a×2

Now, solve for a:

a=
`(20)/(2)`

a=10
`m/s^2`

So, the acceleration of the ball is 10
`m/s^2 .`