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PHY 121
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.
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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: ->->->->->->->->->->->-> :
p=m*v
60g*0.08m/sec = 4.8
Total momentum before collision = 4.8
60Kg * 0.05m/sec = 3
20g*0.07m/sec = 1.4
total momentum after collision = 4.4
@& Good.
Note that the momentum has units as well. When you multiply kg by m/s you get kg * m/s.*@
Total momentum is less after the collision than it is before.
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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: ->->->->->->->->->->->-> :
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90cm/sec would make the two momentum values equal
20kg * 0.09m/sec = 1.8
That added to the 3 would give you 4.8, which matches the momenutm before colllision.
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10 minutes
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&#Good responses. See my notes and let me know if you have questions. &#