engineering

Question

You need to purchase a motor to supply 400 joules [J] in 10 seconds [s]. All of the motors you can choose from are 80% efficient. What is the minimum wattage [W] on the motor you need to choose?
The minimum wattage is............W. (Round your answer to two significant digits.)

Answer 1

Power = Energy/time = 400/10 = 40 watts.  Let W = the motor wattage:

 

W·(0.80) ≥ 40 watts

 

Solve for W.