The Analysis of a Locomotive Pulling Wagons
What is the correct analysis of a locomotive pulling a series of wagons?
A The locomotive can pull the wagons forward only if it weighs more than the wagons.
B The train moves forward because the locomotive pulls forward slightly harder on the wagons than the wagons pull backward on the locomotive.
C Because action always equals reaction, the locomotive cannot pull the wagons. The wagons pull backward just as hard as the locomotive pulls forward, there is no motion.
D The locomotive’s force on the wagons is as strong as the force of the wagons on the locomotive, but the frictional force on the locomotive is forward and large while the backward frictional force on the wagons is small.
Answer:
The correct analysis of the situation is option D: The locomotive’s force on the wagons is as strong as the force of the wagons on the locomotive, but the frictional force on the locomotive is forward and larger while the backward frictional force on the wagons is small. This is in agreement with Newton's Third Law of Motion.
When a locomotive pulls a series of wagons, it can move forward due to the larger frictional force acting forward on the locomotive and less backward frictional force acting on the wagons. This is based on Newton's Third Law of Motion, which states that for every action there is an equal and opposite reaction.
For example, when a person walks, pushing their foot backward against the ground results in the ground exerting an equal and opposite force forward on the foot. Similarly, the wheels of the locomotive exert a force backward on the track, and the track exerts an equal force forward on the locomotive's wheels. This, combined with the locomotive's engine power, allows it to overcome frictional forces and move the entire train forward.
Understanding Newton's Third Law helps explain how the locomotive can successfully pull the wagons forward despite the equal but opposite forces at play. This concept is fundamental in understanding the dynamics of motion and force in various systems.