First adjust the air cushion guide rail.

Because the width l of the photoelectric gate is very small, we use the average speed in a short time instead of the instantaneous speed.

The speed of the slider passing through the photoelectric gate 1 is v1= l △ t1= 0.6m/s.

The speed of the slider passing through the photoelectric gate 2 is v2 = l △ t2 =1.5m/s.

According to the definition of kinetic energy:

Kinetic energy increases △ ek = 12mv2 1? 12mv22=0.473J

Gravitational potential energy decreases △ EP = mgh = 0.5× 9.8× 0.1= 0.490j.

It can be concluded that within the allowable error range, the mechanical energy of the slider is conserved during the movement.

So the answer is: 0.6; ? 0.473; 0.490; Within the allowable error range, the mechanical energy of the slider is conserved during the movement.