Question

Consider the following scenarios.

A moving train is harder to stop than a moving car even if the car is moving at a faster speed.
A chair in your room does not move randomly about on its own.
A rocket ship blasts upward from Earth when forces from its engines push downward toward the Earth.
For each case above, describe what you think are the reasons the motion happens the way it does. See if you can come up with ideas to explain each observation above in terms of motion.

Answer 1

what do u think?

Answer 2

1. A moving train is harder to stop than a moving car even if the car is moving at a faster speed...Because of inertia. Its all about the mass, the huge amounts of inertia of the train make it very difficult to stop/start.
2. A chair in your room does not move randomly about on its own....Because of inertia. Objects at rest tend to stay at rest.
3. A rocket ship blasts upward from Earth when forces from its engines push downward toward the Earth...
Newtons third law. action reaction pairs. The action reaction pair is tricky. The force of the thrust on the earth has nothing to do with the motion of the rocket. Rather, the rocket pushes on thrust particles and the thrust particles push back on the rocket.
thats what i have...

Answer 3

the second one is completely correct.
the first and third are correct to an extent.

Answer 4

could you explain?

Answer 5

Actually , the first one is also correct. I doubt you have studied momentum yet??

Answer 6

Third: Earth does pull the rocket down. But, the thrust particles push back on the rocket with a higher force.

Answer 7

thanks