- #1
Np14
- 27
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Homework Statement
A 0.500 kg ball is dropped from rest at a point 1.20 m above the floor. The ball rebounds straight upward to a height of 0.700 m. What are the magnitude and direction of the impulse of the net force applied to the ball during the collision with the floor?
Homework Equations
FNETt = mv - mvo
k = 1/2mv2
Ug = magh
The Attempt at a Solution
I first solved Ug = K as the ball's gravitational energy will be converted to kinetic energy in an elastic collision. Point A is the highest point (1.2 m); point B is the highest point the ball bounces back up (0.7m).
magh = 1/2mv2
(0.5)(9.8)(1.2) = (1/2)(0.5)(VB)2
That gives VB = 4.85 m/s.
FNETt = mv - mvo
FNETt = (0.5)(4.85) - (0.5)(0)
I tried to solve for Impulse using the first equation (the impulse momentum theorem) and got +2.42 N(s) upward. The answer is +4.28 N(s) upward. What did I do incorrectly?