Question

Consider this situation. The hanging washers are attached to the end of a string that goes through a tubular case, and has a stopper swinging in a circle at the other end of it. :

If the hanging washers have a mass of 331.3 grams, how much centripetal force is on the string?

Answer 1

The centripetal force on the string equals the tension in the string:

$$F_c=T=mv^2/R,$$

where $v$ - velocity of washers, $R$ - length of the string between the tube and washers. Substitution of the mass in kg gives

$$F_c=0.331.3v^2/R.$$