X A worker pushes a crate up a ramp.
Which change to the ramp would be the best way to increase its mechanical
efficiency (ME), and why?
A. Reduce the length of the ramp so that more work is done in less
time.
O B. Wax the sloped surface of the ramp to decrease the friction
between the crate and the ramp.
O C. Cover the ramp with sandpaper to increase the friction between
the crate and the ramp.
D. Reduce the height of the ramp so that less output work is done on
the crate