Question

A ball is thrown vertically upwards from the top of the 75 m high tower it takes 5 seconds to reach the foot of the tower ignoring the effect of the air resistance and taking g=10m/s² find the initial speed of the ball​

Answer 1

Given:-

• Height ,h = 75m

• Time ,t = 5s

• Acceleration due to gravity ,g = 10m/s²

• Final velocity ,v = 0m/s

Solution:-

By using 3rd equation of motion

• v² = u² +2as

Substitute the value we get

→ 0² = u² + 2× (-10) ×75

→ 0 = u² + (-20) ×75

→ -u² = -1500

→ u² = 1500

→ u = √1500

→ u = 38.72 m/s

∴ The initial velocity of the ball is 38.72 m/s.