Question

Last question:

An average person expends ~100 kj to walk 1km. How far will the average car travel by the time it expends the same amount of energy (i.e. 100 kJ) as a person who walked 1 km?

Fuel consumption of average car= 8 km L^(-1)

Heat of combustion of gasoline= 50 kJ g^(-1)

Density of gasoline= 0.7g mL^(-1)

1)2km
2)0.02 km
3) 20 km


How would i solve this?

Answer 1

Energy output of the car is 50 kJ/gram.
So you will need 2 grams to equal 100 kJ (that is, 50 kJ/g x ?g = 100 and solve for ?g).
2 grams is what volume.
mass = volume x density
2 g = v x 0.7g/mL
Solve for v. I think something like 2.85 mL but you need to confirm that to get an exact answer. Then you know the fuel consumption is 8 km/L, how far can you go with 2.85 mL?