Problem 38P

You are explaining why astronauts feel weightless while orbiting in the space shuttle. Your friends respond that they thought gravity was just a lot weaker up there. Convince them and yourself that it isn’t so by calculating the acceleration of gravity 250 km above the Earth’s surface in terms of g.

Solution 38P Consider in the above problem the wheel spinning in 12 seconds from an initial angular velocity of 0.72 rev/s.the initial angular velocity in rad/s is w i 0.72 rev/s w = (0.72 rev/s)(2 rad/rev) i w i 4.5rad/s The angular acceleration of the wheel is = w/t = ( 4.5 rad/s)/12 sec 2 = 0.38 rad/s Then there is only force acting on the wheel is friction.using above results magnitude of frictional torque is = I = (0.30 kg/m )(0.38 rad/s ) 2 = 0.11 N/m