Two people sit opposite each other on the edge of a rotating disk of radius, R, and negligible mass. One person has a mass of 40kg, the other of 50kg. The disk is rotating at 30 revs/min. What is the rotational kinetic energy if R=1.5m?
Rotational Kinetic Energy (KE) = (1/2) x Moment of Inertia (I) x (Angular Velocity (w) )2I=SUM(MR2) = 40 x (1.5)2 + 50 x (1.5)2 = 90 x (1.5)2 = 202.5 kgm2w= 30 revs / min = 30 x (2π/60) = π (rad/s)KE= 0.5 x 202.5 x π2 = 101.25 π2
KE= 999.297.... ~ 1000J
JS
Related Physics A Level answers
All answers ▸Please see below.
How do I derive Kepler's 3rd law using Newton's Law of gravitation, in the case of a circular orbit?
Why can't you hear any noise in space?
Using the substitution u=cosx + 1, show that the integral of sinx e^cosx+1 is equal to e(e-1), for the values of x between x=π/2 and x=0