whats the difference in the energy required to make a car go from 0 - 40mph and 40 - 80mph?

Question

in the same amount of time

Answer 1

Sounds like homework to me.
I am guessing that the question is supposed to be simplified to only worry about kinetic energy.

E=1/2 m * v * v
or more compactly
E=1/2 mv^2

I am not going to do all the work for you but the key is that m will cancel out leaving you with a ratio between 40^2-0^2 and 80^2-40^2. Note that this is NOT the same as the ratio between (40-0)^2 and (80-40)^2

Just been reading some of the other answers, don't trust anything you read here without giving it some careful thought and checking with a textbook.

Answer 2

Ignoring friction wind resistance etc. Kinetic energy = 1/2 mv^2
so getting to 40-80 will require 3 times the energy as getting to 0-40.

Answer 3

Do the calcs using KE = 1/2 mv^2.

Use correct units, i.e. v in ft/s. 40 mph = 58.7 ft/s, 80 mph = 117.3 ft/s.

Examine the differences.

0 mph = 0 energy
40 mph = 1722 m
80 mph = 6880 m

Thus it take 4 times as much energy to acheive the final additional 40 mph as the initial.

This neglects parasitic losses like wind and mechanical friction.

Answer 4

Energy required if at sea level, with normal atmospheric pressure is squared. If 40 hp to maintain 40mph, 160hp required to double speed to 80mph.

Answer 5

First I need to know the car's mass, and what the amount of time is.

Answer 6

It's about 16 times as much. Drag is the main reason and it increases as the cube of the speed which, when integrated gives you a fourth power.

Answer 7

Three dead muslims, go for 150mph

Answer 8

ask engineers