a ball is rolling along a ground with a velocity of 10m/s and comes to rest after 8s. what is its acceleration

-1.25 m/s²

Explanation:

Use the formula a=(v-u)/t,

acceleration a = unknown

final velocity v= 0 m/s (rest)

initial velocity u = 10m/s

time t = 8s

a = (0-10)/8

a = -1.25 m/s²

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.