Centripital acceleration

bakeit1
I am having some trouble with this problem, an explanation on how to do this would be awesome, thanks:

The large blade of a helicopter is rotating in a horizontal circle. The length of the blade is 6.40 m, measured from its tip to the center of the circle. Find the ratio of the centripetal acceleration at the end of the blade to that which exists at a point located 2.86 m from the center of the circle.

I just don't see how there's enough info. to solve this. Please explain.

Homework Helper
Gold Member
What is the formula for centripetal acceleration?

bakeit1

Ac=v^2/r

But the problem only gives you two radius', so I'm not sure what to do next.

bakeit1
nvm, I got the answer. Why couldn't you just explain that I had to divide the two numbers instead of asking me for the Ac formula, which I already knew? I hate teachers that make me in circles trying to find an answer.

Homework Helper
nvm, I got the answer. Why couldn't you just explain that I had to divide the two numbers instead of asking me for the Ac formula, which I already knew? I hate teachers that make me in circles trying to find an answer.

In your first post you didn't say you knew the formula, so how are we to know? You didn't show any work. When we get a post like that we will start off by asking basic questions, to see what your understanding is.

saket
I hate teachers that make me in circles trying to find an answer.

Sorry, to interfere, but I feel very sorry for you "bakeit1". I feel, best way to let students learn, is by letting them rack their mind before providing with a solution. And, if you have some time to notice, this is also the motto of this forum. If you are looking for direct answers, I guess you are at wrong place.

bakeit1
ok

Sorry, to interfere, but I feel very sorry for you "bakeit1". I feel, best way to let students learn, is by letting them rack their mind before providing with a solution. And, if you have some time to notice, this is also the motto of this forum. If you are looking for direct answers, I guess you are at wrong place.

Had I been looking for a direct answer I would have stated so in my first post. I agree, giving someone an answer is meaningless, but i'd rather have you explain the answer, or atleast how to go about doing it.

bakeit1
well

In your first post you didn't say you knew the formula, so how are we to know? You didn't show any work. When we get a post like that we will start off by asking basic questions, to see what your understanding is.

Well there really isn't any work to be shown to this problem; it's more conceptual. Albeit you either know how to do it or you don't. It's not like I could have attempted anything, as I didn't even know where to begin with JUST the two radius'.