Homework Help: Need help with Energy hw

1. Jan 13, 2005

Port

i started to do this engery problem we got for hw but when i tried to solve it i got the wrong answer. could someone plz tell me how to begin this problem?

Tarzan swings on a 30m long vine initially inclined at an angle of 37 degree with the vertical. What is his speed at the bottom of the swing if he starts from rest??

2. Jan 13, 2005

dextercioby

What's your opinion??Post your work...Read the "sticky".We don't nobody' s homework.We only help if people get stuck.But you haven't even started.

Daniel.

3. Jan 13, 2005

Port

i did start it i used the equation 1/2mv^2=mgh but then since their is an angle i tried to do it that way but i got the wrong answer. i don't5 expect anyone to do my hw or else it would be useless to do.

4. Jan 13, 2005

dextercioby

The equation u've written is principially good,but it needs "polishing".Think/analyze the geometry of the problem and try to see which is "h" u need in that equation and its connection with the length and the angle the problem speaks about.

Daniel.

5. Jan 13, 2005

Port

i tried using 30cos37 but that doesn't work so then i tried using 30sin37 and that doesn't work either so i wonder if i am doing something wrong

6. Jan 13, 2005

dextercioby

That "h" is the difference in heigh/elevation between the lowest point of the circular trajectory and the upper one.Assume that the "0" (origin) for the potential energy is chosen to be the lowest point of the trajectory.

Daniel.

7. Jan 13, 2005

Port

so are u saying i should subtract what i get from the cos/sin from the 30???

8. Jan 13, 2005

Port

thx that did work! Now could u help me on my other post plz