A 360LB gorilla climbs a tree to a height of 20ft. Find the work done if the gorilla reaches that height in:

a) 10 seconds b) 5 seconds

Question

A 360LB gorilla climbs a tree to a height of 20ft. Find the work done if the gorilla reaches that height in:

a) 10 seconds     b) 5 seconds

anonymous · Answer

$$W=Fd$$work = force x distance

anonymous · Answer

$$F=ma$$

anonymous · Answer

I get an answer of 72,000 for foot pounds with the integral, so then I divide by 10 seconds and get 7,200 lb-ft, and 14,400 lb-ft for five seconds. The problem is, the book says the answer to b is 72,00 lb-ft, and I don't know why. Why does it take the same amount of force to get the gorilla up the tree twice as fast?

anonymous · Answer

It is independent of time. The acceleration in this problem is the force of gravity. Whether it takes him 5 seconds of 10, the gorilla still had to apply the same force for the same distance.

anonymous · Answer

So how do I set this up, if I never had to divide by ten in the first place? I got an answer of 72,000, and that was wrong, so how do I get from there to 7,200?

anonymous · Answer

wait a sec while I write it out nicely...

anonymous · Answer

$$W=Fd$$$$F=ma;  a=g;F=mg$$$$W=mgd$$$$W=360lb _{m}\times32.174\frac{ ft }{ s ^{2} }\times(G _{c}=\frac{ 1lb _{f} }{ 32.174\frac{ ft }{ s ^{2} } })\times20ft$$

anonymous · Answer

$$G _{c}$$is a conversion factor to convert lb mass to lb force. It is kinda pointless because it cancels out gravity. Seems messed up I know.

anonymous · Answer

That should give you 7200

anonymous · Answer

Does that make any sense?

anonymous · Answer

Just remember that we are looking for a force times a distance. We know the mass and acceleration but when we are working with pounds we wont have a force until we use Gc to convert to lb force. Then we can multiply by our distance.

anonymous · Answer

I was never taught anything about Gc or canceling out the gravity. The book doesn't mention it either, so I assume I don't have to use that conversion. I'm supposed to integrate in this thing to get the result. How would you put this in an integral?

I was taught that weight is a function of force x distance etc. yeah, and that we're supposed to integrate weight as f(x).

anonymous · Answer

Hmmm, I'm sorry but hopefully you will get a different reply because I solved it like one of my engineering problems.  That's the only way I know how to do it.  Sorry @StoneMask

anonymous · Answer

Thanks for trying to help me, @smstevns. Sorry I have no idea about this, lol.

anonymous · Answer

Yup. I have no idea how to do it by calculus either. lol

anonymous · Answer

f=360
d=20
w=fd