Question

If a ball is tossed up vertically from the ground at 20m/s, what is it’s velocity 1 second before reaching maximum height?

Answer 1

Gravitational acceleration = g = -9.81 m/s²

Initial velocity of the ball = V₀ = 20 m/s

Velocity of the ball at maximum height = V₁ = 0 m/s

Time taken to reach maximum height = t₁

V₁ = V₀ + gt₁

0 = 20 + (-9.81)t₁

t₁ = 2.038 sec

Velocity of the ball 1 second before reaching maximum height = V₂

Time the ball has been in air = t₂

t₂ = t₁ - 1

t₂ = 2.038 - 1

t₂ = 1.038 sec

V₂ = V₀ + gt₂

V₂ = 20 + (-9.81)(1.038)

V₂ = 9.81 m/s

Velocity of the ball 1 second before reaching maximum height = 9.81 m/s