Share
Explore BrainMass

Rotational dynamics

A turn-table on a frictionless vertical axis has a radius of 1.5 m and a moment of rotational inertia of 150 kgm^2. It is at rest until a 75 kg person who had been standing still (and who can be treated as a point), begins to walk around the rim at a speed of 2.0 m/s with respect to the turn-table.
a) what is the speed of the person with respect to the Earth?
b)How much work did the person do in bringing the turn-table up to speed?

Solution Preview

Please see the attached file for answer
a) what is the speed of the person with respect to the Earth?
Moment of inertia of turntable= 150 Kg m^2 =It

Radius of turntable= 1.5 m
Mass of the person= 75 Kg
"Moment of inertia of the person with respect to the vertical axis=
M r ^2 =" 168.75 Kg m^2 =Ip

Let the person be moving with angular velocity w p with respect to the earth
Let the turntable be moving with angular velocity w t with respect to the earth

w p= Vp/r where Vp is the velocity of the person with respect to the earth
w t= ...

Solution Summary

Calculates the speed of the person with respect to the Earth and the work the person did in bringing the turn-table up to speed.

$2.19