course PHY 121
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?
NO
60g * 80cm/s=4800g cm/s
20g * 50cm/s=1000g cm/s
40g * 70cm/s=2800g cm/s
###This should be .06kg * .5m/s + .02kg * .7m/s=.03kg*m/s + .014kg*m/s =.044kg*m/s
answer/question/discussion:
• What would the marble velocity have to be in order to exactly conserve momentum, assuming the steel ball's velocities to be accurate?
60g
###This should be .048kg*m/s -.03kg*m/s=.018kg*m/s so .02kg*v_marble=.018kg*m/s which =.018kg m/s / .02kg =.9m/s
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