In: Physics
1. Think about the forces acting on a train engine and the train
cars that it pulls.
a.) Draw a force diagram for the 5 forces (one of the forces is
friction) acting on the engine as it accelerates forward along the
rails.
b.) Draw a force diagram for the 4 forces acting on a train car as
it is pulled by the accelerating engine.
c.) By Newton’s 3rd Law, the train car pulls backward on its engine
exactly as hard as the engine pulls forward on the train car. Since
Newton’s 3rd Law is correct, the force by the engine on the car
should be equal and opposite to the force by the car on the engine.
Therefore, the entire train shouldn’t go anywhere. Using your force
diagrams from parts (a) and (b) above, explain why this analysis is
wrong. That is, show that there is a net force on the engine and
the train car.