Work and Power Homework problem

AI Thread Summary
Tarzan swings from a tree using a 20 m vine at a 45-degree angle, aiming to reach Jane in another tree, with the final angle being 30 degrees. The problem involves calculating Tarzan's speed just before he reaches Jane, utilizing the work-energy theorem and conservation of energy principles. The discussion reveals confusion about how to apply these concepts, particularly regarding the necessary quantities for the energy equation. Participants suggest focusing on initial and final kinetic and potential energy to solve the problem. The overall sentiment reflects a struggle to correctly apply the conservation of energy to find the solution.
Santorican
Messages
10
Reaction score
0
This question, I have absolutely no idea what to do.


Question: Tarzan, in one tree, sights Jane in another tree. He grabs the end of a vine with length 20 m that makes an angle of 45 degrees with the vertical, steps off his tree limb, and swings down and then up to Jane's open arms. When he arrives, his vine makes an angle of 30 degrees with the vertical.

Part A)
Calculate Tarzan's speed just before he reaches Jane. You can ignore air resistance and the mass of the vine.

I figured that I am going to have to use the work energy theorm, W=change in K and then break it down into smaller bits, but there is no mass and I have no idea what work is equal to so I am totally stumped.
 
Physics news on Phys.org
Try using conservation of energy. The vine does not actually do any work on Tarzan.
 
So by using Ue=Uk and breaking it down I can figure out the answer!? That is so beautifully simply!

Thank you
 
Okay so I tried using the conservation of energy Ue=Ke and then broke it down to mgh=(mv^2)/2 and then simplified to find velocity but this is where I am confused.

I tried using V=(2gh)^1/2 and it was wrong.

Then I tried to find the component of gravity at a 30 degree angle with respect to y and used V=(2(sin30g)h)^1/2 and it was wrong.

Then again with respect to x, don't have a clue at this point, V=(2g(cos30)h)^1/2 and it too was wrong.

So right now I am utterly completely lost. Please help :(
 
Well, for conservation of energy you need 4 quantities to set up the equation:
initial kinetic energy and initial potential energy
final kinetic energy and final potential energy
 
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Struggling to make relation between elastic force and height'
Hello guys this is what I tried so far. I used the UTS to calculate the force it needs when the rope tears. My idea was to make a relationship/ function that would give me the force depending on height. Yeah i couldnt find a way to solve it. I also thought about how I could use hooks law (how it was given to me in my script) with the thought of instead of having two part of a rope id have one singular rope from the middle to the top where I could find the difference in height. But the...
Back
Top