Phy 121
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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: ->->->->->->->->->->->-> :
The momentum before would be the same as the momentum after. I think this is because of the law of conservation of momentum.
That would be so in an isolated system, but you have to do the calculation.
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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 solve for this mathematically, I think we would use the following formula and work the problem out as below:
M1 * v1 = m2 *v2
80 grams * 80cm/s = 80 grams * v2
We know that the velocity after for the marble is 70 cm/sec. To make it equal to the velocity of the steel ball would need to have slowed down to 10 cm/s.
Right idea, but there's a 60 gram ball in there too.
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20 minutes
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