Chapter 4, Problem 1Q

Why does a child in a wagon seem to fall backward when you give the wagon a sharp pull forward?

To determine

Does a child in a wagon seems to fall backward when the wagon moves a sharp pull forward.

Answer to Problem 1Q

Yes, a child in a wagon seems to fall backward when you give the wagon a sharp pull forward.

Explanation of Solution

In this case the child and the wagon are initially at rest. The child is sitting or standing in the wagon. His feet or the bottom will contact with the wagon.

When you give a sharp pull forward to the wagon, the child’s bottom part or the feet will moves forward with the wagon. Because the force of friction acts between the child and the wagon.

Conclusion:

In this case, the bottom part of the child begins to move to forward but the upper part of the child follows the Newton’s first law (the law of inertia) and remains stationary. So the child falls backward.

Therefore, the child in a wagon seems to fall backward when we give the wagon a sharp pull forward.