Question

I need help with force body diagram for a person jumping... Can someone tell me if I listed the forces correctly for each stage?
1. Person at rest before jumping: W, down; N, up.
2. Person pushing off before leaving ground: W, down; F up; N, up.
3. Person in air: W, down; Air resistance, up.
4. Person landing: W, down; F down; N, up.
5. Person at rest after landing: W, down; N, up.

Answer 1

1. Correct

2. Technically, you are pushing, so it should be F down. The normal force N is then increased by that amount. This allows the normal force to then propel the person off the ground because it is greater than force of gravity. In number 1, W = N. In this case, W < N.

3. Air resistance is a frictional force. It always acts opposite to motion. So it should be air resistance down while the person goes up. When the person goes down, the air resistance would be up.

4. Correct

5. Correct