Find the minimum speed

  • #1
85
0

Homework Statement


You've taken a summer job at a water park. In one stunt, a water skier is going to glide up the 2.0-m-high frictionless ramp shown, then sail over a 5.0-m-wide tank filled with hungry sharks. You will be driving the boat that pulls her to the ramp. She'll drop the tow rope at the base of the ramp just as you veer away.
What minimum speed must you have as you reach the ramp in order for her to live to do this again tomorrow?

Homework Equations


U=mgh, K=0.5mv^2, W=Fd

The Attempt at a Solution


when the water skier is standing on the ramp, there is only gravitational potential energy
Ei=U=m*2m*g
then, when I am pull the water skier, there are kinetic energy and work by pulling the water skier
Ef=K+W=0.5mv^2+5F, F=mg because the skier is skiing on water

thus, Ei+Ef= m*g*2=0.5mv^2+5mg= g(h-d)=0.5v^2

I get v=7.7m/s

I am not sure this is the right answer or not.
 

Answers and Replies

  • #2
Simon Bridge
Science Advisor
Homework Helper
17,874
1,655
I don't follow your reasoning - how did you work out the energy needed to get over the 5m distance?
 
  • #3
85
0
I don't follow your reasoning - how did you work out the energy needed to get over the 5m distance?
while the skier is sailing on water, I think the work on water just equal to mgd.
 
  • #4
Simon Bridge
Science Advisor
Homework Helper
17,874
1,655
Why?
And what has that got to do with jumping the shark tank?
You are asked for the speed at the bottom of the ramp right?
 

Related Threads on Find the minimum speed

  • Last Post
Replies
3
Views
1K
Replies
13
Views
3K
Replies
2
Views
2K
Replies
1
Views
2K
Replies
6
Views
3K
Replies
4
Views
2K
Replies
3
Views
3K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
1
Views
783
  • Last Post
Replies
11
Views
3K
Top