When useful energy output of simple machine is 100J and the total energy is 200J, the efficency is ?

What is the function of the commutator in a dc motor? a. to spin the magnet b. to change direct current into alternating current c. to change alternating current into direct current d. to spin the wire coil

Curious carl calculated the density of a cube to be 4.50 g/cm3. what is the density of the cube in g/l?

Which accounts for an increase in the temperature of a gas that is kept a constant volume