• Support PF! Buy your school textbooks, materials and every day products Here!

How to calculate the height of a skier

  • Thread starter JiJiasd
  • Start date
  • #1
7
0

Homework Statement


I want to calculate the height h of the skier in this figure
upload_2016-5-23_16-6-52.png


Homework Equations


potential energy and kinetic energy and there is no friction

The Attempt at a Solution



mgh = 0,5 *m*v^2
v=√ (2*g*h)

Now calculate the h when he goes up

mgh= 0,5 *m*√ (2*g*h)^2


Am I doing right ?

Thanks



[/B]
 

Answers and Replies

  • #2
240
42
Now calculate the h when he goes up

mgh= 0,5 *m*√ (2*g*h)^2
What you got is an identity. You need more information of the person on the top of the hill to get his condition, such as velocity~
 
  • #3
115
8
mgh = 0,5 *m*v^2
v=√ (2*g*h)

This is right but after this, only calculate with its vertical component (v*sin(28 deg)), when calculating h.
 
  • #4
115
8
What you got is an identity. You need more information of the person on the top of the hill to get his condition, such as velocity~
These informations are enough, you dont need more!
 
  • #5
115
8
You only got an identity, because you didnt calculate with the right component of speed.
 
  • #6
7
0
thank you all
 
  • #7
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
32,781
5,050
You need to be careful with 'h'. There is a specific height in the problem which is labelled h, and there is the generic h in the equation gh=v2/2. Don't get them mixed up.
First, find the velocity at the launch point.
 

Related Threads on How to calculate the height of a skier

  • Last Post
Replies
2
Views
749
Replies
15
Views
2K
Replies
6
Views
1K
  • Last Post
Replies
1
Views
1K
Replies
6
Views
3K
  • Last Post
Replies
2
Views
5K
  • Last Post
Replies
2
Views
8K
Replies
4
Views
3K
Replies
3
Views
2K
Top