Quote Originally Posted by ironchef
Shoot again, but see if theres formulas, i cant remember them for shit lol.
A 2.3 kg rock initially at rest loses 403 J of potential energy while falling to the ground. Assume that air resistance is negligible.
(a) Calculate the kinetic energy that the rock gains while falling.
___J
(b) What is the rock's speed just before it strikes the ground?
___m/s

The main formula is PE(before) + KE (before) = PE (after) + KE (after)
where PE = mgh
and KE = 1/2mv^2



and another one that should be easy
A cannonball is fired at 50 m/s at an angle of 30 degrees. How high does it go? (Hint: determine the vertical velocity, and use conservation principles.)
___m
I just cant seem to figure it out. I tried doing trig functions but it doesnt work out