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A 0.12-kg ball is moving east at velocity v when it is hit by a bat, causing it to reverse direction and have?
A 0.12-kg ball is moving east at velocity v when it is hit by a bat, causing it to reverse direction and have a speed of 14 m/s west. If the momentum of the ball change by 2.4 kg.m/s west, what is the initial velocity of the ball?
Answer 18 m/s
-18 m/s
6 m/s
24 m/s
1 Answer
- Anonymous9 years agoFavorite Answer
If you chose west to be the positive x direction, then the initial momentum, p(i), is
p(i) = m (-v) = 0.12 kg (-v)
v is negative because it is moving to the east (and we said that west was positive).
The final momentum, p(f) is
p(f) = 0.12 kg (14 m/s) = 1.68 kg m/s
Δp = p(f) - p(i)
Δp = 2.4 kg m/s = 1.68 kg m/s - 0.12 kg (-v)
The two negative signs will cancel
2.4 kg m/s = 1.68 kg m/s + 0.12 kg (v)
We find v = 6 m/s moving to the east.
TaDa!