- #1
PeachBanana
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Homework Statement
A tennis ball of mass = 0.060 kg and speed = 26 m/s strikes a wall at a 45° angle and rebounds with the same speed at 45° .
Homework Equations
Δp = pfinal - pinitial
horizontal velocity = (26 m/s)cos 45°
There's a picture if you all care.
The Attempt at a Solution
pintial = mv
pintial = (0.060 kg)cos 45°
pinitial = 1.1028 kgm/s
pfinal = - pintial
I made this relationship because it is now going in the opposite direction.
pfinal = -1.1028 kgm/s
Δp = -1.1028 kgm/s - 1.1028 kgm/s = -2.2056 kgm/s
The answer is positive and I cannot understand why.
What is the direction of the impulse given to the ball?
A. Upward
B. Downward
C. Left
D. Right
I've eliminated B and C but I'm still unsure. The sine and cosine of forty-five degrees are the same.