Force Exerted From the Ground During a Jump.

  • Thread starter Thread starter JSpadafore
  • Start date Start date
  • Tags Tags
    Force Ground Jump
AI Thread Summary
To determine the force exerted by the ground during a jump, the jumper's weight (w) is essential. The initial speed required to reach a height of 60cm is calculated as 3.4m/s. The jumper accelerates from rest to this speed while rising 0.5m, allowing for the calculation of acceleration. The relationship between weight and mass is crucial, as the force can be expressed in terms of the jumper's weight. Understanding these dynamics will lead to the correct formulation of the force exerted by the ground.
JSpadafore
Messages
1
Reaction score
0
Hello! This problem has been driving me crazy all week long, and now I am down to the last few hours before the assignment is due. Any help would be greatly appreciated!

Homework Statement



An average person can reach a maximum height of about 60cm when jumping straight up from a crouched position. During the jump itself, the person's body from the knees up typically rises a distance of around 50cm. To keep the calculations simple and yet get a reasonable result, assume that the entire body rises this much during the jump.

Part A required me to find the initial speed a person would need to reach a maximum height of 60cm, for which I correctly answered 3.4m/s.

Part B is where I find myself stuck. It asks, "In terms of this jumper's weight (w), what force does the ground exert on him or her during the jump?"The answer will read:
F= ___ w.

Homework Equations



ƩFy=may
w=mg
...

The Attempt at a Solution



Honestly, I've just been trying to figure out how I am supposed to get anywhere without first knowing the mass of the person jumping. I suspect it has something to do with the initial speed I had calculated for Part A being related to an opposite force, coming from the ground going to the person jumping.
 
Last edited:
Physics news on Phys.org
The body accelerates from zero to 3.4 m/s speed during the first stage of the jump, while rising 0.5 m. Determine the acceleration. From the acceleration, you can find the force.

ehild
 
JSpadafore said:
Honestly, I've just been trying to figure out how I am supposed to get anywhere without first knowing the mass of the person jumping.
You are asked to express the answer in terms of the jumper's weight. So given the weight as W, what's his mass?
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Calculating the Force of a Jump on the Moon
Replies
10
Views
3K
A little annoying doubt -- Initial vertical speed of a jumping flea
Replies
5
Views
704
How much force do I exert on the Earth?
Replies
6
Views
3K
Bungee jumping and Conservation of energy
Replies
3
Views
2K
Physics 1 Parabolic Motion Question Confusion
Replies
15
Views
1K
Max KE of a squirrel jumping from the top of a tree
Replies
6
Views
2K
Momentum and impulse of jump problem
Replies
11
Views
4K
Solve Jumper Question Homework: Part A & B with Initial Speed & Force
Replies
2
Views
9K
Finding force that ground has on person
Replies
2
Views
1K
Calculating Velocity when Stuntman Jumps from 1.25m Height
Replies
30
Views
2K

Hot Threads

Recent Insights

Back
Top