Question

A horse is harnessed to a cart. If the horse tries to pull the cart, the horse must exert a force on the cart. By Newton's third law the cart must then exert an equal and opposite force on the horse. Since the two forces are equal and opposite, they must add to zero, so Newton's second law tells us that the acceleration of the system must be zero and therefore no matter how hard the horse pulls, it can never move the cart.

• A. True the horse won't be able to move the cart.
• B. False, the horse will move the cart as this is a non inertial frame and newton's laws are not valid here
• C. False, the horse will move the cart as air friction is the external force on the system.
• D. False, the horse cart system will move as friction from ground is the external force on the system.

Answer 1

The correct option is D

False, the horse cart system will move as friction from ground is the external force on the system.

Think for 30 seconds and try to get this on your own. Then proceed to the next video for the explanation.