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teggenspiller
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Homework Statement
A 0.2 baseball if pitched with a velocity of 40 m/s and is then batted to the pitcher with a velocity of 60 m/s. What is the magnitude of change in the ball’s momentum?
A. 4 kg*m/s
B. 8 kg*m/s
C. 2 kg*m/s
D. 20 kg*m/s
Homework Equations
change in momentum = m(vf-vi)
The Attempt at a Solution
.2 (60-40) =4
4m/s, OR would it be 20, since .2*40=8 and .2*60=12
and add them together since they are in opposite dirctions, to get the TOTAL magnitude of change??
ANOTHER example:
A softball with a mass of 0.11 kg moves at a speed of 12 m/s. Then the ball is hit by a bat and rebounds in the opposite direction at a speed of 15 m/s. What is the change in momentum of the ball?
A. –1.3 kg*m/s
B. –1.6 kg*m/s
C. –0.33 kg*m/s
D. –3.0 kg*m/s
should i add the momenta, since different directions to get 3.0 (D) or subtract vf from vi to get C, .33
i know this seems like a dumb q that has probably an obvious answer, but little things like this could BREAK my grade in the test