The specialty of an athlete on the women's track team is the pole vault. She has a mass of 60.0 kg and her approach speed is 9.20 m/s. When she is directly above the bar, her speed is 2.40 m/s. Neglecting air resistance and any energy absorbed by the pole, determine the amount she has raised herself as she crosses the bar.

She raised approximately 4 meters as she crosses the bar

Explanation:

Energy Conservation

In the absence of air resistance and any other energy-absorbing events, the total mechanical energy is conserved. Recall the mechanical energy is the sum of the gravitational potential energy and the kinetic energy:

When our athlete is at the ground level her height is 0, thus she has only kinetic energy given by the speed she's at when starting the jump:

Later when she's directly above the bar, she has both energies since some speed remains at a certain height h we must calculate. The mechanical energy is

Equating both energies

Simplifying by m and rearranging

Solving for h

She raised approximately 4 meters as she crosses the bar