Dean Potter is known for slacklinging across a 915 metter deep ravine in Yosemite National Park with no safety gear. If his mass is 77 kg, how much potential energy did he have?

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: