Question

A car traveling at 30m/s screeches to a halt, leaving 55 m long skid marks. what was the cars acceleration while braking

Answer 1

For this problem we use the derived equations for rectilinear motion at constant acceleration. The equation is written below:

2ax = v² - v₀²
where 
a is the acceleration
x is the distance
v is the final velocity
v₀ is the initial velocity

Since the car comes to a stop eventually, v=0. Substituting the values,

2a(55) =0² - 30²
a = -8.18 m/s²