Question

A 200g block on a 50cm long string swings in a circle, it's frictionless and 75rpm. What is its speed and tension on string

Answer 1

angular velocity = (75x2pie)/60
=2.5pie ras^-1
linear velocity(or speed) at end of string, v = radius x angular velocity
v= 0.5 x 2.5pie
v=3.93 ms^-1

tension of string (I beleve is centeral force aplied by string), F= (mv^2)/r
F= (0.2 x 3.93^2)/0.5
F=6.18 N
(sorry if wrong)

Answer 2

The speed of the block is given by:

`image`

Where,

w: angular speed

r: radius of the circular path.

The angular velocity must be in radians over seconds:

`image`

The radius must be in the subway:

`image`

Then, the speed is given by:

`image`

`image`

The tension of the rope is the centripetal force.

By definition, the centripetal force is:

`image`

Where,

m: mass of the block in kilograms

Substituting values:

`image`

Answer:

its speed and tension on string are:

`image`