# Physics

posted by .

Jenn Suhr recently won the gold medal in this summer’s Olympic games in pole vault. Her record is 16 ft,
2 in. (She did less than that to win gold this summer.) If all of her gravitational potential energy came only
from her kinetic energy, calculate (in m/s) the running speed necessary to make this vault. Assuming the
vaulting pole to be elastic, does the pole “add”energy to this system? Explain.

• Physics -

H = 16 ft, 2 inches = 194 in. = 4.9276 m

Set M g H = (1/2) M Vo^2 and solve for the required initial velocity Vo. Note that the mass cancels out.

Vo = sqrt(2 g H) = 9.83 m/s

This formula assumes that the center of mass of the vaulter is raised the full amount H. Actually, because of the way the body bends over the bar, the vaulter's center of mass passes under the bar if the best vaulting technique is used. Also, the vaulter starts the vault with his of her center of mass already about 0.9 meters above the ground. In a 4.93 meter vault, the center of mass only gets increased by about 3.9 meters. This reduces Vo to about 8.7 m/s, more typical of an actual vault by a world class vaulter.

With respect to the question about the flexible elastic pole, this does not add energy to the system, but it allows most of the kinetic energy to be stored as pole elastic deformation energy and later released at the maximum height of the vault.

## Similar Questions

1. ### algebra 2

Define a variable and write an inequality. Then solve. A local summer basecall team plays 20 games each season. So far, they have won 9 games and lost 2. How many more games much they win this season to win at least 75% of all their …
2. ### algebra

Define a variable and write an inequality. Then solve. A local summer baseball team plays 20 games each season. So far, they have won 9 games and lost 2. How many more games must they win this season to win at least 75% of all their …
3. ### SAT Essay

Please grade according to the SAT Rubric. Question: Do you agree that persistence is a major factor in success?
4. ### English

My new friends are all great. 1. How do you like them?
5. ### 3 grade english ms sue

fact and opinion a fact tells something that can be proved true or false. an opinion tells someones ideas or feelings.words that telll fellings, such as should or best, are clues to opinions. yu can ask an expert or use reference book …
6. ### Physics?

In Rutherford's scattering experiments, alpha particles (charge = +2e) were fired at a gold foil. Consider an alpha particle, very far from the gold foil, with an initial kinetic energy of 2.0 MeV heading directly for a gold atom (charge …
7. ### physics

In Rutherford's scattering experiments, alpha particles (charge = +2e) were fired at a gold foil. Consider an alpha particle, very far from the gold foil, with an initial kinetic energy of 3.3 MeV heading directly for a gold atom (charge …
8. ### physics

At the 2004 Olympic Games in Athens, Dwight Phillips won the gold medal in men’s long jump with a jump of 8.59 m. If the angle of his jump was 23°, what was his takeoff speed?
9. ### math

a local summer baseball team plays 20 games each season. so far, they have won 9 games and lost 2. how many more games must they play win this season to win at least 75% of all their games?
10. ### math

Use the information below to write and simplify an expression to find the total weight of the medals won by the top medal-winning nations in the 2012 London Olympic Games. The three types of medals have different weights. U.S.A. Gold=46 …

More Similar Questions