Unit is m^3 or metres cubed. You need to multiply the three dimensions of the block to get the volume.
A ruler can be used to measure the edges.
R=U^2/P=120*120/40=360 ohm
P2=U2^2/R=132*132/360=48.4 w
power increase ratio (48.4-40)/40=21%
The answer is letter b, the rotor will jam. It is because if there are too many washers, it will be overcrowded, making the rotor to jam in it, where this will lead the motor to dysfunction or not function properly. It is best not to place too many washers in the end of the shaded pole motor shaft to prevent further complications.
Your hypothesis can be that the group with calculators would finish faster than the group without calculators.