Register to reply

Jumper Question

by dkirov1
Tags: jumper
Share this thread:
Jun24-12, 02:24 PM
P: 1
1. The problem statement, all variables and given/known data

A person reaches a maximum height of 64 cm when jumping straight up from a crouched position. During the jump itself, the person's body from the knees up rises a distance of around 41 cm. To keep the calculations simple and yet get a reasonable result, assume that the entire body rises this much during the jump.

Part A: With what initial speed does the person leave the ground to reach a height of 64 cm?
Part B: In terms of this jumper's weight W , what force does the ground exert on him or her during the jump?

I figured out the first part, but I can't figure out the second part. :(

Also the answer to part B has to be a number? This is online homework and the answer is in the format:


2. Relevant equations


3. The attempt at a solution
The velocity for part A was 3.5
I tried to figure out the time by using v=d/t, and got t=.117 seconds which seems wrong.
I tried to figure out the a so I used vf-vo/t=29.91???
and using 29.91 as a tried to figure it out. But I'm just stuck. I have no idea.
Phys.Org News Partner Science news on
Scientists develop 'electronic nose' for rapid detection of C. diff infection
Why plants in the office make us more productive
Tesla Motors dealing as states play factory poker
Jun24-12, 06:43 PM
P: 54
The force the ground exerts on the person is going to last 41 cm, the initial velocity would be 0, the final velocity would be the answer to part a, from there you can solve for acceleration.
Jun25-12, 01:45 PM
P: 48
A very simple way to solve this, assuming this is a closed system, would be to use the attached formula (Egmax=Ekmax); rearrange algebraically. I would assume the force the ground exerts on her would be gravity, so F is mg or F=Wg.

Hope this helps.
Attached Thumbnails

Register to reply

Related Discussions
Jumper in mechanical assembly Electrical Engineering 2
Ski jumper Introductory Physics Homework 1
Bungee Jumper Physics Lab Question Introductory Physics Homework 1
Bungee Jumper Question Classical Physics 9
High Jumper Physics Question General Physics 1