I'm having an arguement that I can't settle.
Which is more economical?
1) Build up speed to a constant 56mph slowly over a 1 mile distance and hold that speed for 3 miles.
or 2) Accelerate to 56mph briskly (but not at full throttle) over say a 1/4 miles distance and hold that speed for 3.75 miles.
Assuming the car is most economical at 56? Journey time will be shorter in the second scenario but which would use less fuel overall? In scenario 1 the mpg in the car is about 25-30 mpg while accelerating. In scenario 2 the mpg will be 15-20 mpg while accelerating but the car will return 56 mpg at a constant 56 mph.
Show you workings - this is not meant to be a maths question though?
Its a real pig to argue this one and I just wondered what you guys thought about it? (Especially our resident physicists!)