# Homework Help: Energy needed to move a car

1. Aug 26, 2011

### aroc91

1. The problem statement, all variables and given/known data

This isn't really a homework problem, but this section seems most applicable. I'm trying to debunk Tom Ogle's vapor engine claims.

http://peswiki.com/index.php/Directory:Tom_Ogle%27s_Vapor_Fuel_System [Broken]

However, I have no experience at all with physics and even with all the reading I did, I still can't figure it out. Ogle made the claim that he drove his 2.5 ton (2267 kg) car 100 miles (160 km) on 1 gallon (originally 200 miles on 2 gallons, I reduced it for simplicity's sake) of gas. I've looked up the energy density of gasoline (136 million joules/gallon), but I can't figure out how much energy it takes to move 2267

Also, just for the time being, I'm making the assumption (although incorrect) that the efficiency of an internal combustion engine is 100%. I can always multiply the final result by 0.3 to reflect the real world efficiency (more or less).

2. Relevant equations

F = m*a
W = F/d

3. The attempt at a solution

I know that a joule is the work done by applying a force of 1 newton over the distance of 1 meter, but the whole acceleration thing throws me off when I try to plug stuff in. I don't really know what to do with it. Sorry if this isn't deemed a proper attempt.

Last edited by a moderator: May 5, 2017
2. Aug 26, 2011

### PeterO

An interesting quote from the first section of the wiki article"

Our cars already capture almost all of it. There aren't any significant gains to be made, regardless of how 'optimized' the system is

With modern cars, the rule of thumb is 1/3 of the energy is used to move the car, 1/3 of the energy goes out the exhaust pipe as heat, 1/3 of the energy goes out through the radiator as heat. The energy referred to here is the chemical energy in the petrol [or gas if you must]

Perhaps wiki should be saying "Our cars already capture as much of the useful energy that they can".

Last edited by a moderator: May 5, 2017