Sky divers jump out of a plane at an altitude of 6000 m. How much time will pass until they deploy their parachutes at an altitude of 1260 m? Assume that air resistance is negligible.
t = s

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: