Question

Train cars are connected to each other by couplers, which are under tension and compression when the locomotive speeds up and slows down respectively. What happens to the tension in each coupler from the first train to the last train when speeding up? What happens to the compression in couplers when the train slows down?
A. The coupler for the first car has the most tension speeding up and the most compression slowing down.
B. The coupler for the first car has the most tension speeding up and the least compression slowing down.
C. The coupler for the first car has the least tension speeding up the least compression slowing down.
D. The coupler for the first car has the least tension speeding up and the most compression slowing down.
E. Tension and compression are equal for each coupler in the train.

Answer 1

In order to solve this question we need to understand the definition of force which states that force is push or pull that causes a body to change its state either from motion to rest or rest to motion. Compression means atoms squeeze it down so just after compression atoms react and release themselves and tension is atoms when they are extended too much so after tension atoms try to get back in their state.

Complete answer:
As a train moves somewhere it has to speed up and somewhere it slows down. When the train speeds up suppose from rest then due to inertia of rest several cars try not to move so at that time couplers between cars try to move every car in speed.So when train speed up tension decreases till last car so the coupler between engines or locomotive and first car must accelerate all cars by applying some amount of force. When the train slows down then every car due to inertia of motion tries to be in motion so now the coupler between the locomotive and first car must apply some force to stop all other cars.

So the correct option is A.

Note: It should be remembered that caboose is different from all cars. If the car speeds up then every car wants to rest so for the last car coupler has to accelerate only caboose or in other way each coupler is accelerating less mass behind it. If the car slows down the last coupler has to apply some force on the caboose.