A 73.0 kg father and his 45.0 kg son are sitting on opposite sides of a 4.00m seesaw at the playground. the pivot point is fixed at the midpoint of the board. where must the father position himself to horizontally balance the seesaw if his son sits at the end of the board?

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: