A ball is thrown straight up with an initial velocity of 35.7 m/s. How long does

it take to hit the ground?

y = v₀t - gt²/2

For y=0 (back to where we started),

0 = t (v₀ - gt/2)

t=0 (which we knew) or v₀ - gt/2 = 0

v₀ = gt/2

2v₀ = gt

t = 2v₀/g

t = 2 (35.7 m/s) / (9.8 m/s/s) = 7.3 seconds

Answer: 7.3 seconds