#$&*
PHY 121
Your 'cq_1_24.2' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** CQ_1_24.2_labelMessages **
A steel ball of mass 60 grams, moving at 80 cm / sec, collides with a stationary marble of mass 20 grams. As a result of the collision the steel ball slows to 50 cm / sec and the marble speeds up to 70 cm / sec.
Is the total momentum of the system after collision the same as the total momentum before?
answer/question/discussion: ->->->->->->->->->->->-> :
It is close.
Before: m * v = .06 kg * .8 m/s = .048 kg m/s for Object 1
m * v = .02 kg * 0 m/s = 0 kg m/s for Object 2
Total before: .048 km m/s
After: m * v = .06 kg * .5 m/s = .03 kg m/s
m * v = .02 kg * .7 m/s = .014 kg m/s
Total after: .044 kg m/s
#$&*
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: ->->->->->->->->->->->-> :
Total before - steel ball after = marble after
.048 kg m/s - .03 kg m/s = .018 kg m/s
.018 kg m/s / .02 kg = .9 m/s
It would need to be going .9 m/s instead of .7 m/s.
#$&*
&#Very good responses. Let me know if you have questions. &#