A 1.00 x 104 W electric motor is used to lift a 955 kg object vertically 25.0 m at a constant
velocity in 45.0 s. What is the efficiency of the
motor?

52%

Explanation:

1W = 1 J/s

motor input is 10000 J/s

Potential energy change

PE = 955(9.81)(25.0) = 234,213.75

power needed to change the PE in that time

P = 234,213.75/ 45 = 5,204.75 Watts

motor is 5204.75 / 10000 = 0.520475 or 52% efficient

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.