Tower of Terror Physics Questions (1 Viewer)

[Abzzski]

Need help with this question

Question The electromagnetic energy applied to the system

The magnetic drives are like an electric motor. They use 1000kW of power to accelerate the cart along the horizontal section of track in 7 seconds. Calculate the total Electromagnetic Energy applied to the system (use W=Pt). Give your answer in kJ.

My working out

W=Pt
W= 1000 kW x 7 seconds
= 7000kW

What is the answer in kJ ?? I need to convert 7000kW to kJ

 

[jazz519]

I think you have your units incorrect.
W=work (which is measured in joules)
P = power (measured in watts, note watts = joules/second)
t = time (seconds)

so W=1000*kW*7s
W = 1000 * kJ/s*7*s (you can see in tis line that units for the second will cancel)
w = 7000 kJ

 

[Abzzski]

thanks I was confused because of the question.