a stone is tied to a 80 cm long string and whirled in a horizontal circle with a constant speed. it completes 25 revolutions in 14 seconds. what would be the magnitude of its acceleration. My answer: I calculated the angular velocity but can not use it to find the accelaration since i would need the radius of the circle which i have not been given. a friend multiplied the square of the angular velocity with the length of the string and got the a which turned out to be right. why did he do that?

Question

wolfe8 · Answer

Well, if you're wondering about the radius, wouldn't the length of the string be that? Try sketching it.

anonymous · Answer

the length would be the radius if the system lied on a horizontal plane right? i assumed in this case, the length would be slightly elevated from the imaginary plane on which the circle was, do you get me? hence it can not be the radius.

anonymous · Answer

but i guess you are right, it makes sense. thanx a lot

wolfe8 · Answer

When it says it is spun into a horizontal circle, it is understood that we spin it such that the stone is then on the same plane as the center. That's what I think.

anonymous · Answer

ok got it thanks