Question
If action is always equal to the reaction, explain how a horse can pull a cart.
Solution
The horse pulls the cart with a force (action) in the forward direction. The cart also pulls the horse with an equal force (reaction) in the backward direction. This way, the two forces get balanced. The horse pushes the ground with its feet in the backward direction, while pulling the cart. So, the reaction of earth makes it move in the forward direction alongwith the cart.
