Posted by **Fabian** on Sunday, February 14, 2010 at 1:51pm.

An object is thrown downward with an initial speed of 5 m/s from a height of 78 m above the ground. At the same instant, a second object is propelled vertically from ground level with a speed of 50 m/s.

The acceleration of gravity is 9.8 m/s2. At what height above the ground will the two objects pass each other?

Answer in units of m.

- physics -
**bobpursley**, Sunday, February 14, 2010 at 4:31pm
The height of each is

h1=78+(-5)t-4.9t^2

h2=0+50t-4.9t^2

set them equal, solve for t.

Then put time t into either, to solve for final height.

- Physics -
**Joe**, Thursday, October 4, 2012 at 7:09pm
The acceleration due to gravity on planet X is

one fifth that on the surface of the earth.

If it takes 3.9 s for an object to fall a certain

distance from rest on earth, how long would

it take to fall the same distance on planet X?

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