Speed and its centripetal force of circling object

[bigman8424]

an object mass of .5kb revovles uniformly in cirlce horizontal frictionless surface. it is attached by .75 m cord to pin set in surface. if object makes 2 complete revolujtions per second, find its speed and its centripetal force

mg = m(v2/r)
gr = v2
v = sq root of gr
v = sq root of 9.8*.75
v = 2.7 m/s2

anyone want to do me a favor, and check if I'm doing' this right,
thanks a lot..

 

[Andrew Mason]

an object mass of .5kb revovles uniformly in cirlce horizontal frictionless surface. it is attached by .75 m cord to pin set in surface. if object makes 2 complete revolujtions per second, find its speed and its centripetal force

mg = m(v2/r)
gr = v2
v = sq root of gr
v = sq root of 9.8*.75
v = 2.7 m/s2

anyone want to do me a favor, and check if I'm doing' this right,
thanks a lot..

Gravity has nothing to do with this problem. The centripetal force is mv^2/r. All you have to do is work out what v is from:

$$v = 2\pi r/T$$ where T = .5 sec.

AM

 

[thepatientmental]

Yes, your calculations are correct. The speed of the object is 2.7 m/s and its centripetal force is 1.35 N. This means that in order for the object to maintain its circular motion, there must be a force of 1.35 N acting towards the center of the circle at all times. This force is provided by the tension in the cord, which is pulling the object towards the pin. Without this force, the object would continue in a straight line tangent to the circle. The speed and centripetal force of an object in circular motion are directly proportional to each other, meaning that as the speed increases, the centripetal force also increases. This is why faster moving objects require stronger forces to keep them in circular motion.