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

Tarzan swings down to save Jane

1. Homework Statement

Tarzan (mass 98.3552) stands on a 4.45 m cliff next to a river. He grabs a vine of length 30.1 m whose point of support is directly above Jane (mass 57.5336). He grabs Jane at the bottom of his swing and has just enough speed to make it to the other side. How long does the rescue take?

2. Homework Equations

I assume some kinematics.

3. The Attempt at a Solution

I already solved the other two parts (Tarzans speed at bottom (9.339 m/s)and height of other side (1.7714 m). I triedd d = .5at^2 for both sides of the swing (down and back up) but didn't expect it to be right. It probably has something to do with harmonic motion?
 

Answers and Replies

225
0
I can see simple harmonic motion working here. divide it into two parts with seperate values for omega (in the SHM, not omega of the rope). Not too hard to do for the first part because you know the final speed. set that equal to (omega)(amplitude) where amp is the max angle. For the second part, do it the same way, but first calculate the initial speed by using energy conservation. Can you go from there?
 
225
0
on second thought, I guess you already know that initial speed because you used momentum to find the height of the other side. That makes it easier.
 

Related Threads for: Tarzan swings down to save Jane

  • Last Post
Replies
10
Views
9K
  • Last Post
Replies
7
Views
14K
  • Last Post
Replies
3
Views
418
Replies
6
Views
6K
  • Last Post
2
Replies
26
Views
6K
  • Last Post
Replies
2
Views
3K
  • Last Post
Replies
22
Views
4K
  • Last Post
Replies
3
Views
769
Top