Question

A horse pulls on a carriage. By Newton's third law, the carriage pulls back on the horse with equal force. Why do the action and reaction forces just described not balance each other out?
A.
because this is not an action--reaction pair
B.
because action and reaction forces are not equal in magnitude in this case
C.
because action and reaction forces act in the same direction in this case
D.
because the action force acts on the carriage, while the reaction force acts on the horse

Answer 1

Answer:

By Newton's third law the cart must then exert an equal and opposite force on the horse. ... If it doesn't accelerate, and it started it rest, it must remain at rest (by the definition of acceleration), and therefore no matter how hard the horse pulls, it can never move the cart