Average acceleration of driver in car-tree collision

[tak181]

Hello everyone. I am having a little trouble with this problem and I was wondering if you could give me a hand with it.

A car traveling 85 km/h strikes a tree. The front end of the car compresses and the driver comes to rest after traveling 0.80 m. What was the average acceleration of the driver during the collision? Express the answer in terms of "g's," where 1.00 g = 9.80 m/s^2.

V(0)=85 km/h
X(0)=0
V=0
X=.80 m

 

[Fermat]

Use the suvat eqn

v² - u² = 2as

 

[HallsofIvy]

Use the suvat eqn

v² - u² = 2as

Where v= final velocity, u= initial velocity and s= distance traveled.


Another way to do that problem is to use the two equations

v= u+ at

s= (1/2)at²+ ut

Again, u is initial velocity, v is final velocity, s is distance moved. t now is the time of the collision. You have two equations in two unknowns, a and t.