# A ball is thrown vertically from ground level and it rises to a maximum height of 50 m. Calculate the time at which 50 m is reached.?

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- ?Lv 72 months ago
v = u + at

so, 0 = u - gt

i.e. u = gt

Also, v² = u² + 2as

so, 0 = u² - 2g(50)

Then, u² = 100g

Hence, (gt)² = 100g

=> g²t² = 100g

i.e. t² = 100/g

Hence, t = 10/√g => 3.19 seconds

:)>

- oldschoolLv 72 months ago
Max height is defined as the moment when Vy = 0

Vy(t) = Vyo - g*t = 0 at t = Vyo/g but 50 = Vyo²/19.6 so Vyo² = 19.6*50 = 31.3²

t = 31.3/9.8 = 3.2s <<<<<

- billrussell42Lv 72 months ago
time to fall 50 m = t = √(2h/g) = √(2•50/9.8) = 3.19 s

falling object starting from rest (and reverse)h is height in meters, t is time falling in seconds,g is acceleration of gravity, usually 9.8 m/s²v is velocity in m/sh = ½gt²t = √(2h/g)v = √(2gh)h = v²/2gv = gt

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