A pilot ( with a mass of m ) in an aircraft follows a vertical circular motion of radius 2.70 km at a constant speed of 225 m/s. If the normal force acting on the pilot at the bottom of the circle is 2082 N, calculate m.

Amachinist turns the power on to a grinding wheel, at rest, at time t = 0 s. the wheel accelerates uniformly for 10 s and reaches the operating angular velocity of 96 rad/s. the wheel is run at that angular velocity for 40 s and then power is shut off. the wheel slows down uniformly at 1.5 rad/s2 until the wheel stops. in this situation, the time interval of deceleration is closest to: