Question

9. How many kilometers per liter will a car obtain if its engine is 25 percent efficient and it encounters an average force of 1000 Newtons? Assume the energy content of gasoline is 40,000,000 joules per liter (J/L).

Answer 1

Given:

efficiency of engine,
`\eta = 25% = 0.25`

Average Force, F = 1000 N

Energy content of gasoline, E = 40000000 J/L

Solution:

Part of energy that is utilized is given by:

`E_(1) = \eta * E`

`E_(1) = 0.25* 40000000`

`E_(1) = 10000000 = 1* 10^(7) J`

Nw,

To calculate the distance 's', we know that the amount of work done is the energy utilized and it can be given as the product of Force and the distance:

`E_(1) = F* s`

⇒
`s = (E_(1))/(F) = (10^(7))/(1000) = 10^(4)m = 10 km`

Therefore, the distance moved by the car per liter in km is 10 km