- #1
Imparcticle
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A railroad diesel engine weighs four times as much as a freightcar. If the diesel engine coasts at 5km/h into a freightcar that is initially at rest, how fast do the two coast after they couple together?
Given:
m1= 4m2
m2
v1=5km/h
v2=0
unknown : v3
formula:
m1v1+ m2v2=m3v3 (i.e., Total momentum before=total momentum after)
work:
m1v1+ m2v2=m3v3 --> (4 x m2)(5km/h) + (m2)(0)=m3v3
(20km/h)m2=m3v3
answer --> 20km/h=v3
Given:
m1= 4m2
m2
v1=5km/h
v2=0
unknown : v3
formula:
m1v1+ m2v2=m3v3 (i.e., Total momentum before=total momentum after)
work:
m1v1+ m2v2=m3v3 --> (4 x m2)(5km/h) + (m2)(0)=m3v3
(20km/h)m2=m3v3
answer --> 20km/h=v3
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