Finding height using Conservation of Energy

In summary, the skier with a mass of 61.00 kg slides down a ski jump with negligible friction and takes off horizontally. The height of the ski jump is 6.70 m and the horizontal distance traveled is 9.80 m. Using the equation for conservation of energy and the formulas for kinetic and potential energy, the skier's velocity as he leaves the cliff is calculated to be 8.38 m/s.
  • #1
Kajayacht
29
0

Homework Statement


A skier (m=61.00 kg) starts sliding down from the top of a ski jump with negligible friction and takes off horizontally. If h = 6.70 m and D = 9.80 m, find H.

I already found the velocity as he leaves the cliff to be 29.2 m/s

Here's a picture of it: http://img264.imageshack.us/my.php?image=prob21agz5.gif

Homework Equations


E[1] + W[non conservative] = E[2]
K= .5mv^2
U= mgh


The Attempt at a Solution



w[nc]= 0 (no friction)
K[1]= 0, U[2] = 0 so K[2] = U[1]

K[2]= .5*61*29.2^2
K[2]= 26005.52

26005.52 = mgH
26005.52/ (61*9.8) = H
H=43.5
 
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  • #2
I already found the velocity as he leaves the cliff to be 29.2 m/s

Can you show how you got this? That's a pretty high speed.
 
  • #3
You're right, and after reworking I found the speed to be 8.38 m/s which gave me the right answer
 
  • #4
which I found using V= d* (square root of( g/2h))
 
  • #5
That looks much better!
 

1. How do you use conservation of energy to find height?

To find height using conservation of energy, you will need to use the equation: Potential Energy = Kinetic Energy + Gravitational Potential Energy. You will also need to know the mass of the object and the initial and final velocities. First, set the equations for potential energy and kinetic energy equal to each other. Then, substitute in the known values and solve for the height.

2. What is conservation of energy?

Conservation of energy is a fundamental principle in physics that states that energy cannot be created or destroyed, only transferred or converted from one form to another. This means that the total amount of energy in a closed system remains constant.

3. Can conservation of energy be used to find height in any situation?

No, conservation of energy can only be used to find height in situations where there is no external force acting on the object other than gravity. This is because conservation of energy only applies to a closed system where there is no energy being added or taken away.

4. What are the limitations of using conservation of energy to find height?

The main limitation of using conservation of energy to find height is that it assumes no energy is lost due to friction or other external forces. In reality, these factors can affect the accuracy of the calculated height. Additionally, this method only works for objects that are initially at rest or have a known initial velocity.

5. Are there any other methods for finding height besides using conservation of energy?

Yes, there are other methods for finding height, such as using trigonometry or using other principles of physics like projectile motion. The method you choose will depend on the specific situation and the available information. However, conservation of energy is a widely used and reliable method for finding height in many scenarios.

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