Question

part1:Think about the forces acting on an engine and the train it pulls.

a.) Draw a force diagram for the 5 forces acting on the engine as it accelerates

forward along the rails.

b.) Draw a force diagram for the 4 forces acting on the train as it is pulled by the

accelerating engine.

c.) By Newton’s 3

rd

Law, the train pulls backward on its engine exactly as hard as the

engine pulls forward on the train. Since Newton’s 3

rd

Law is correct, the force of

the engine on the train should be equal and opposite to the force of the train on the

engine. Therefore, the train shouldn’t go anywhere. Using your force diagrams

from parts (a) and (b) above, carefully explain why this analysis is wrong.

part2: Consider a piano sitting in a stationary freight elevator. Draw separate force

diagrams for (1) the forces that act on the piano while the piano sits in the elevator and

for (2) the forces that act on the elevator with the piano inside it. For all the forces in the

two force diagrams, identify and list the action-reaction pairs by Newton’s third law.

Finally, identify any forces that are equal and opposite because of Newton’s second law,

and not the third law. (Hint: Think carefully! There are some forces here that are equal

and opposite, but are NOT action-reaction pairs! There will be four action-reaction pairs,

and not all of the forces will act on the piano or elevator. For example, the force on the

piano by the Earth is an action-reaction pair with the force on the Earth by the piano.

These are both gravitational forces. However, this second force is not on this force

diagram because it is a force that acts on the Earth, and the force diagram shows forces

on the piano.)

please answer both parts

Answer 1