Question

A 4.1-kg ball is thrown from the top of a 4-m tall building (point A) with a speed of 1 m/s at an angle 2 degrees above the horizontal. If air resistance is negligible, what is the value of the kinetic energy of the ball as it hits the ground?

Answer 1

Gravitational acceleration = g = 9.81 m/s²

Mass of the ball = m = 4.1 kg

Height of the building = H = 4 m

Initial velocity of the ball = V₁ = 1 m/s

Angle at which the ball is thrown = = 2^o

Kinetic energy of the ball as it hits the ground = E

By conservation of energy the potential energy and kinetic energy of the ball initially is equal to the kinetic energy of the ball as it hits the ground.

mgH + mV₁²/2 = E

E = (4.1)(9.81)(4) + (4.1)(1)²/2

E = 162.934 J

Value of kinetic energy of the ball as it hits the ground = 162.934 J