# Homework Help: Working out speed without time

1. Oct 24, 2012

### johnjohnson

If a man who weighs 1000Newtons(N) makes a bungee jump off a bridge with a 6m bungee rope, this rope has a elastic constant of 2000N/m

A) what is the fastest speed he reaches
B)what is his maximuum kinectic energy
C)how far will bungee rope extend until energy is transformed to elastic potential energy

2. Relevant equations
F=ma, F=kx E=1/2*k*x^2 these are all i know

3. G= 9.81m^2 Gravity*weight/2000 sorry IDK guys please help GCSE Science

2. Oct 24, 2012

### mishek

Are you familiar with potential and kinetic energy?

3. Oct 24, 2012

### johnjohnson

yes i m thanks for replying

4. Oct 24, 2012

### mishek

Could you divide this jump in phases? What energy do you have at the bridge, what energy do you have before the "rope" starts stretching?

5. Oct 25, 2012

### AJ Bentley

Check your question values. That bungee rope looks rather stiff. You might have picked up an extra zero.

6. Oct 25, 2012

### johnjohnson

Thanks for trying to help me guys appreciate i ve got the answer now
first 1/2*m*v^2 = mgh
then pug in the values

7. Oct 26, 2012

### mishek

Hello, John.

Your equation above would work for a situation before rope starts stretching.

You have a 3 key situations: before jump (potential energy is max), before stretching of the rope (kinetic energy is max) and after stretching ("spring" energy).

Please look into photos I attached.

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