A disc 28 mm in radius rotates at a constant rate of 1.2 x10^5 rev/hr, about its central axis. Determine the tangential speed at a point 12mm from its center

157m/s

Explanation:

We can convert 1.2 x10^5 rev/hr, to rad/secs for unit consistency

w=1.2×10^5rev/hr ×( 2π rad)/rev ×1 min/60sec

w=13083rad/sec

We can express the tangential speed inform of angular speed

Given speed at a point= 12mm12×10^-3m

V=wr

=13083rad/sec×12×10^-3

=157m/s

Hence the tangential speed at a point 12mm from its center is 157m/s