# Spring rate and deflection.

1. Mar 30, 2013

### aande

1. The problem statement, all variables and given/known data
A 3000lb car with a wheelbase of 100 inches and track of 50 inches sits on level ground with equal weight on each wheel. The effective spring rate is 700 lb/in at each wheel. One wheel is now raised by 1 inch and the car is allowed to settle to a new equilibrium. What is the new set of corner weights?

2. Relevant equations
F=k*x

3. The attempt at a solution
I tried solving this equation through reasoning and using Matlab. Obviously when the car is sitting on level ground the weight on each tire is 750lb. But as the left rear tire is raised I am unsure how to reason out what the new weight would be. I know the weight would increase on the front right and I think on the rear left. I'm not sure how to show this mathematically though.

2. Mar 30, 2013

### SteamKing

Staff Emeritus
Draw a free body diagram of the car. Since the car is in equilibrium with three wheels instead of four, the amount of weight on each wheel can be determined by writing and solving the equations of statics.

3. Mar 31, 2013

### aande

The wheel is still in contact with a surface its just one inch higher than the rest. It's like the car is on a 1 inch block which is under one wheel.

4. Mar 31, 2013

### SteamKing

Staff Emeritus
The car is still in equilibrium. There is an additional load at the lifted wheel due to the compression of the spring.