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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.
** CQ_1_24.2_labelMessages **
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: ->->->->->->->->->->->-> :
Total initial momentum=( 0.06 kg * .8 m/s) + (.02 kg * 0 m/s) = 0.048 kg*m/s Total final momentum=( 0.06 kg * .5 m/s) + (.02 kg * .7 m/s) = (0.03 kg*m/s) + (0.014 kg*m/s) = 0.044 kg*m/s
The total momentum before is greater than the total momentum after the collision.
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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: ->->->->->->->->->->->-> :
m1v1 + m2v1 = m1v2 + m2v2
= (60 g) * 80 cm/s = 60 g * 50 cm/s + 20 g * v2
so that 4800 gcm/s = 3000gcm/s + 20v2
v2 = 90 cm/s.
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