A3-kg ball is thrown with a speed of 8 m/s at an unknown angle above the horizontal. the ball attains a maximum height of 2.8 m before striking the ground.

if air resistance is negligible, what is the value of the kinetic energy of the ball at its highest point?

13.5 J

Explanation:

mass of ball, m = 3 kg

maximum height, h = 2.8 m

initial speed, u = 8 m/ s

Angle of projection, θ

use the formula of maximum height

Sin θ = 0.926

θ = 67.8°

The velocity at maximum height is u Cosθ = 8 Cos 67.8 = 3 m/s

So, kinetic energy at maximum height

K = 0.5 x 3 x 3 x 3

K = 13.5 J

force is mass*acceleration.

we have a very small mass: 11.4*0.001 kg

if we want 0.035n of force, we need an acceleration:

0.035 = 11.4*0.001*a

a = 0.035/(11.4*0.001) m/s^2