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Phy 121
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** 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: ->->->->->->->->->->->-> :
No, but the momentum is supposed to be equal before a collision to the 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: ->->->->->->->->->->->-> :
Well we know that the momentum before the collision is equal to the momentum after the collision. Therefore we can set all of this equal and solve for the unknown.
First we need to convert all of these values to kg and m/s. 80 cm/s = 0.8 m/s, 50 cm/s = 0.5 m/s, 70 cm/s = 0.7 m/s, 60 g = 0.06 kg, 20 g = 0.02 kg
0.06 kg * 0.8 m/s + 0.02 kg * v = 0.06 kg * 0.5 m/s + 0.02 kg * 0.7 m/s
0.048 Newtons + 0.02 kg * v = 0.03 Newtons + 0.014 Newtons
0.02 kg * v = 0.044 Newtons - 0.048 Newtons
0.02 kg * v = -0.004 Newtons
v = -0.2 m/s
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20 minutes
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