Calculating Average Power for 1170 kg Car

[kmikias]

Hi guys i have a question on power and work i guess you gone help me out here is the question.

1.A 1170 kg car starts from rest and accelerates uniformly to 10 m/s in 16.1 s . Assume that air resistance remains constant at 302 N during this time.Find the average power developed by the engine. Answer in units of hp.

here is what i did

Power = work / time
so average power = KE/t



work = 1/2 . mv^2
work= 1/2 * 1170 * 10^2
= 29250 J

so Power = W/t = 29250 J/ 16.1
= 3633.5403 w
after that i changed watt to hp.

 

[Q_Goest]

Ok, good... you calculated the average power to accelerate the vehicle. But what about the work done to overcome drag? You have a nice constant 302N drag over this time. If you have force over a distance you can find work. Can you determine the distance the car went? Once you have work done by the air on the vehicle, divide by time to find average power.

 

[baba89]

The calculation you have done is correct. The average power developed by the engine is 3633.5403 watts. To convert this to horsepower, we can use the conversion factor 1 horsepower = 746 watts. Therefore, the average power in horsepower would be 3633.5403 watts / 746 watts = 4.87 hp. This means that on average, the engine of the car is producing 4.87 horsepower during the 16.1 seconds of acceleration. It is important to note that this is the average power and not the maximum power, as the engine may produce more power at certain points during the acceleration.