- #1

bnashville

- 7

- 0

## Homework Statement

For the following calculations, assume a typical electric car will need to apply a constant forc of 165 N to maintain a typical highway speed of 100 km/hr (27.7778 m/s).

A: What power (watts) is needed to maintain this speed?

B: What energy (Joules) is needed to travel 100 km at 100 km/hr?

C: Given that the combustion of gasoline will produce 4.73x10^7 J /kg of gasoline consumed, and the density of gasoline is .74 kg/L, if a car can get 32 mi/gal at 100 km/hr, what power is being generated by the combustion reaction? (in watts)

There are several additional parts to answer on this question, but I think I can get going if I get these answered.

## Homework Equations

Power = Force x Velocity

Energy = Power x Time

## The Attempt at a Solution

I think I have the first 2 answers but wanted to check that they were correct:

A: 165 N x 27.7778 m/s = 4583.34 Watts

B: 4583.34 Watts x 3600s = 1.65x10^7 Joules

C: I didn't get much further than unit conversion on this one.

32.0 mi/gal = 51499 m / 3.7854 L = 13604.63888 m / L

.74 kg/L x 3.7854 L = 2.8011 kg...and this is where I start to trail off and have no grasp on what I'm doing..

Thanks for the help!