A 160g stone, tied to a thread, swings in a horizontal circle with a 100 cm diameter. If the maximum tension the thread can withstand before snapping is 28n, find the A) Maximum speed of the stone. B) Acceleration of the stone at this speed. For A I used V=sqrt (r)(F)/m and come up with 9.35 m/s. On part B if I use a=v^2/r I come up with 174.84 m/s^2. This is a crazy speed. Is B a trick question where there is no acceleration. The only other formulas I know are a=delta t/delta v. I would appreciate any assistance. Thanks.

Question

A 160g stone, tied to a thread, swings in a horizontal circle with a 100 cm diameter. If the maximum tension the thread can withstand before snapping is 28n, find the  A) Maximum speed of the stone. B) Acceleration of the stone at this speed. For A I used V=sqrt (r)(F)/m and come up with 9.35 m/s. On part B if I use a=v^2/r I come up with 174.84 m/s^2. This is a crazy speed. Is B a trick question where there is no acceleration. The only other formulas I know are a=delta t/delta v. I would appreciate any assistance. Thanks.

bobpursley · Answer

tensionmax=mv^2/r You are correct in both counts, the way to work it, and your answers. Yes, it is crazy.

mack · Answer

God Bless you! I have been agonizing over this for some time. Thank you so much!