Aball is thrown vertically upward on the moon and returns to it starting point in 4.0s. the acceleration due to gravity there is 1.60m/s^2 downward. find the ball’s original speed

Explanation:

applying motion equations we can find the answer,

v = u + a*t

Let assume ,

u = starting speed(velocity)

v = Final speed (velocity)

t =  time taken for the motion

a = acceleration

for the complete motion it takes 4 s. that means to reach the highest point it will take 4/2 =2 seconds

by the time of reaching the highest point subjected to the gravity , the speed shoud be equal to zero

we consider the motion upwards , in this case the acceleration should be negative in upwards

that is,

v = 0 , a = -1.6    , t =2

v = u + at

0 = u -1.6*2

u = 3.2

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s