Question

A grinding wheel is a uniform cylinder with a radius of 7.50 cm and a mass of 0.700 kg . Calculate the applied torque needed to accelerate it from rest to 1750 rpm in 5.70 s . Take into account a frictional torque that has been measured to slow down the wheel from 1500 rpm to rest in 47.0 s.

Answer 1

The moment of inertia of the grinding wheel is - (0.700 kg) (7.50x102 m)-1.98x103 kg.m2 The angular acceleration of wheel is 1750 rad's 1-0 60 32.15 rad/s 5.70 s The angular decleration of wheel is 0-1500rad/s (47.0 s) 60 a"= --3.34 rad/s The amount of applied torqu e is τ-1(e+ α')-(1.98 x 10-3 kg.m2)(32. 15 rad/s2 + 3.34 rad/s2)-0.0703 Nm