Your friend says that if Newton’s third law is correct, no object would ever start moving. Here is his argument: You pull a sled exerting a 50 N force on it. According to Newton’s third law the sled exerts the force of 50 N on you in the opposite direction. The total force is zero, thus the sled should never start moving. But it does. Thus Newton’s third law is wrong. What is your opinion about this answer? How can you convince your friend of your opinion? pls help

Explanation:

You pull a sled exerting a 50 N force on it , sled also exerts a force on you . These forces are action and reaction force , as per third law of Newton . These two forces are equal and  opposite . But they do not act on the same object so they do not cancel each other . They act on different objects , one on the sledge and the other on you . Due to force on sledge , sledge moves in the direction of force or towards you . You will start moving in opposite direction if frictional force of ground is nil or less .