# Answer to Question #5752 in Mechanics | Relativity for Melanie

Question #5752
when you have a rock on a string spinning it around, if you have a original tension with a radius and velocity, how would you find the breaking strength of a string if the problem also states a second radius and velocity but not the tension?
1
2011-12-22T08:30:30-0500
Let&#039;s make the following denominations:

F1 - the original tension
V1 = original velocity
V2 = second velocity
M - the mass of a rock

We need to find the mass of a rock at first.
Using the first case we have that the centripetal acceleration of a rock is
Ac1 = V1&sup2;/R1.
Now let&#039;s use the second Newton&#039;s law:
F1 = M*Ac1 ==&gt; M = F1/Ac1 = F1/(V1&sup2;/R1) = F1*R1/V1&sup2;.

Now let&#039;s find the breaking strength of the string.
In the second case we have that the centripetal acceleration of a rock is
Ac2 = V2&sup2;/R2.
So, we can find the breaking strength usind the second Newton&#039;s law again:
F2 = M*Ac2 = (F1*R1/V1&sup2;)*(V2&sup2;/R2) = (F1*R1*V2&sup2;)/(V1&sup2;*R2).

Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!