Answer
The equal and opposite forces of Newton's third law are acting on two different objects - one on the wagon and the other on us. The wagon may thus experience a non-zero net force, which causes it to accelerate forward.
Work Step by Step
The equal and opposite forces of Newton's third law are acting on two different objects - one on the wagon and the other on us. The wagon may thus experience a non-zero net force, which causes it to accelerate forward.
