# The effect of mass distribution on acceleration of a car.

1. Jul 15, 2012

### ANX

Hi, I am amidst writing my 4k word high school physics paper (IB extended essay) and am in need of some help/guidance.

The experiment I am conducting is as stated above. I have been changing the distribution of a set of masses from front, middle and rear on a model car and recording changes in acceleration. I have also conducted this procedure on the same model with 4WD, FWD and RWD sources of drive.

2. Relevant equations
As this is a very long paper, I will need to get into the theory behind the experiment. Therefore, my question is; what is the theory behind the forces and moments acting on the wheels of a car during acceleration.
If there are any other aspects of physics I could possibly explore, please let me now. :)

3. The attempt at a solution

I have tried finding articles on the net to no avail, therefore any help or even links/sources would be extremely helpful.

Last edited: Jul 15, 2012
2. Jul 15, 2012

### CWatters

deleted

3. Jul 15, 2012

### PhanthomJay

The force that accelerates the center of mass of the car is the friction (traction) force between the driving tires and the road. The greater the available static friction force, where Ff_max = uN, the greater will be the acceleration, since F_net = ma. The friction force is maximized when the normal force, N, between the driving tires and the road, is the highest. Racing cars almost always use RWD, because when the car accelerates, it tends to lift up the front wheels and put greater normal force on the back wheels, due to the friction force moment about the center of mass. You might want to run a few numbers to see how varying mass distribution affects the maximum possible acceleration. Be sure to sum moments about the center of mass when doing so, or if you use the concept of a pseudo force 'ma' acting rearward through the c.o.m., you can sum moments about any point, if you are familiar with that concept.