Question

A 150g mass tied on a string is whirled in a vertical circle of radius 30cm with a uniform

speed. At the lowest position the tension in the string is 9.5N.Calculate the velocity of the
mass.
(2 marks)​

Answer 1

v = 4 m/s.

Step-by-step explanation:

Given that,

Mass of the object tied on a string, m = 150 g = 0.15 kg

The radius of the vertical circle, r = 30 cm = 0.3 m

At the lowest position, the tension in the string is 9.5N.

We need to find the velocity of the mass.

At the lowest point, the net centripetal force is given by :

`F=(mv^2)/(r)+mg`

Putting all the values to find v.

`(mv^2)/(r)=F-mg\\\\v^2=(r(F-mg))/(m)\\\\v^2=(0.3* (9.5-0.15* 10))/(0.15)\\\\v=4\ m/s`

So, the velocity of the mass is 4 m/s.