# physics

posted by maura

An object is dropped from a height H above the ground. This free-falling object requires 0.904 s to travel the last 34 m before hitting the ground.
From what height H above the ground did
the object fall? The acceleration of gravity is 9.8 m/s^2.

i understand that t= .904s
distance is 34m
and a = 9.8m/s^2
But I'm not sure what else to do here?

1. Elena

H=g•t²/2
H-34 = g• (t-0.904)²/2

g•t²/2 – 34 = 0,5•g•(t²-2•0.904•t +0.904²)
8.86t=38
t=38.8.86 = 4.3 s.
H= g•t²/2 = 9.8•4.3²/2 = 90 m

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