A diesel locomotive coasting at 10 km/h has an inelastic ...

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A diesel locomotive coasting at 10 km/h has an inelastic collision with a stationary flatcar. The locomotive weighs four times as much as the flatcar. How fast does the locomotive-flatcar combination move when stuck together?
 
  What will be an ideal response?

Question 2

Are small ripples sent out across the surface of a lake truly waves, as that word is used in physics?
 
  A) Yes, because the water itself doesn't go anyplace but simply oscillates up and down.
  B) No, because true water waves are longitudinal.
  C) Yes, because the water itself moves across the lake, away from the source of the wave.
  D) No, because the water's motion is mass motion, similar to the motion of a ball that has been thrown.
  E) No, because the water itself doesn't go anyplace but simply oscillates up and down in one place.

[rnehls]

Answer to Question 1

Answer: Momentum before collision = momentum after collision.
masslocomotive  10 km/h. = (masslocomotive + massflatcar)  v.
So v = masslocomotive /(masslocomotive + massflatcar)  10 km/h. Or,
v = 4 massflatcar/(4 + 1) massflatcar  10 km/h = 8 km/h. So the coupled cars move at 8 km/h.

Answer to Question 2

A

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Thanks for the timely response, appreciate it

[xiazhe]

Wow, this really help