posted by Li on .
A child throws a snowball with a horizontal velocity of 18m/s directly toward a tree, from a distance of 9m and a height above the ground of 1.5 m.
After what interval does the ball hit the tree?
At what height above the ground will the snowball hit the tree?
Determine the snowball's velocity as it strikes the tree.
I was able to figure out that the time is .5s and the height is .3m; according to the back of the book, these are correct. I can't figure out the last answer, though. Can someon eplease help?
Well, if you found the answer to the first and second question, you should be able to figure that out via the kinematics equations esp if you got the height question
that's the problem, I can't....
Use conservation of energy. The kinetic energy when it hits the tree will be
(1/2) M V2^2 = (1/2) M V1^2 + M g H
where h is the 1.2 m distance that it falls vertically and V1 is the initial velocity of 18 m/s. The M's cancel. Solve for V2
V2^2 = V1^2 + 2 g H