: In order to push a pile of crates forward, a student applies a force. There is a friction
force that pushes backward on the crates with a magnitude half as much as the force
from the student. If the student pushes with a force of 300 N to the right, the net
force on the crates will be ---

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: