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phy121
Your 'cq_1_24.2' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_24.2_labelMessages **
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A steel ball of mass 60 grams, moving at 80 cm / sec, collides with a stationary marble of mass 20 grams. As a result of the collision the steel ball slows to 50 cm / sec and the marble speeds up to 70 cm / sec.
• Is the total momentum of the system after collision the same as the total momentum before?
answer/question/discussion: ->->->->->->->->->->->-> :
here is what we know
steel ball: m = .6 kg, v0 = .8m/sec, vf = .5m/sec
marble: m=.2kg, v0 = 0m/sec, vf = .7m/sec
so we need to find the momentum before and after
m1v1+m2v2 is momentum before
.6kg * .8m/sec + .2kg * 0 = .48 kgm/sec
Momentum after m1v1` + m2v2` gives
.6kg * .5m/sec + .2kg * .7m/sec = .44kgm/sec
Total momentum before and after the collision are not the same
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• What would the marble velocity have to be in order to exactly conserve momentum, assuming the steel ball's velocities to be accurate?
answer/question/discussion: ->->->->->->->->->->->-> :
To use m1v1 + m2v1 = m1v2 + m2v2 we get
.6kg * .8m/sec + .2kg * 0 = .6kg * .5m/sec + .2kg * v2`
.48 kgm/sec = .30 kgm/sec +.2kg*v2`
.2kgv2` = .18 kgm/sec
V2` = .9 m/sec
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20 minutes
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&#Very good responses. Let me know if you have questions. &#