Question

A .1 kg mass is attached to a string 75 cm long and swings in a horizontal circle, revolving once every .8s. calculate the tension of the string.

Answer 1

Answer:

4.62N

Explanation:

Since the motion covers 1 circle (or 2π rad) per 0.8 seconds, its angular velocity is

$\omega=2\pi/0.8 = 7.85 rad/s$

Radius of the circular motion is r = 75 cm or 0.75m. We can calculate the centripetal acceleration of this mass

$a_c = \omega^2r = 7.85^2 * 0.75 = 46.2 m/s^2$

From Newton's 2nd law, we calculate the centripetal force, which is also the tension of the string:

$F_c = a_cm = 46.2 * 0.1 = 4.62 N$