Purpose

To show how energy is converted between different forms during different stages of a jump, then to use those different types of energy to determine some interesting characteristics of a jump.

Background

For the purposes of this lab we will be examining three different stages of a jump: prelaunch, launch and maximum height. For the purposes of this lab we will be ignoring any energy that may be converted into thermal energy. A description of each phase of the jump is given below.

Prelaunch You are squatting down as low as you care to go, from this position you will rapidly rise to the next position.

Launch You are in a fully upright position, your feet are just about to leave the ground.

Max Height You are up in the air as high as you will go.

In each case, the red dot represents your Center of Mass. (Check out how center of mass plays into the High Jump)

https://www.youtube.com/watch?v=XBtBdNHBNSI

For this lab we will be accounting for three different types of mechanical energy in each phase:

• Stored Chemical Energy (SCE) - Energy that is stored up in the jumpers leg muscles. (this is considered to go to zero once the jumper has left the ground).
• Gravitational Potential Energy (GPE) - Energy that the person has because of their height above the floor.
• Kinetic Energy (KE) - Energy that the person has because they are moving.

These three types of energy all add up to the Total Mechanical Energy (TME).

Prelab Questions

1. How does the TME compare at each moment of the jump? Why is this? (5 points)

2. At what phase will the jumper have the maximum: (2 points each)

SCE -

GPE -

KE -

3. What would be the best height to choose to be zero height? Why? (4 points)

Data

(5 points each)

Jumper Mass (in kg):

Height At Prelaunch (in meters):

Height At Launch (in meters):

Maximum Height (in meters):

Analysis

(15 points)

Use your data to fill out the table below and answer the following questions.

Position	SCE	GPE	KE
Prelaunch
Launch
Max Height

Show the equation(s) used and your work for the questions below.

1. How many food Calories would you have to eat in order to have the energy to perform this jump? (1 food Calorie = 4184 J) (5 points)

2. How fast were you moving when you left the ground in m/s? (5 points)

3. What is the average force you needed to exert in order do the proper amount of work between the prelaunch and launch position?(*Hint - set your maximum GPE as equal to the Work needed.) (5 points)

Extension Question - The One Candy Bar Jump

How high could you jump if you used up all the energy in one Fun Sized Candy Bar (50 Calories)? How fast would you leave the ground? How much force would it take?

Answer these three questions by filling out the following:

TME in Joules = (5 points)

Table (15 points)

Position	SCE	GPE	KE
Prelaunch
Launch
Max Height

Show the equation(s) used and your work for the questions below.(5 points each)

Max height (m):

Take-off speed (m/s):

Average Force (N):