# Suspension of a car

1. Sep 8, 2016

### Pao44445

1. The problem statement, all variables and given/known data
A guy is 60 kg and he gets in a car which is 500 kg. the center gravity of the car is 0.3 cm lower, find the spring constant of the suspension
2. Relevant equations
F = -kx
F = mg
3. The attempt at a solution

I got the answer but it s very low valve, the springs of the car should be high, don't they?
here 's my equation
There are 2 forces acting on the car, Weight and Restoring Force of springs then
mg = -kx
( 560 kg )( -9.8 m/s2 ) = - (k) ( 0.3x10-2 m )

2. Sep 8, 2016

How low ?

3. Sep 8, 2016

### Pao44445

sorry,my mistake
I've re calculated it, I got a pretty high valve instead, does it this valve is possible?
k = ( 560 kg )( 9.8 m/s2 )( 102 ) / 0.3
k = 1829333.333 N/m

4. Sep 8, 2016

### BvU

Not that low, then. But wrong.
There is one small thing: the 0.3 cm is caused by how many kilograms ?

5. Sep 8, 2016

### Pao44445

60 kg of a man, oops
k = ( 60 kg )( 9.8 m/s2 )( 102 ) / 0.3
k = 196,000 N/m

6. Sep 8, 2016

### BvU

Way to go ! Well done.