How to calculate stopping distance?

Question

How to calculate stopping distance? 

Answer 1

My method is nearly identical to Arturo O.

Suvat formula   v² - u²  =  2  a  s

v = final velocity   u = initial velocity   s = distance

This assumes constant acceleration/deceleration

So ....

0 - u²  = 2  a  s       

The Force causes the decleration so  F=ma => a = F/m

Decleration = > a is negative   so  a = - F/m

 

- u² = 2 (- F/m) s

Solving for s

s = u²  m  /  2 F

 

 

Answer 2

Suppose you want to stop a body of mass m moving at initial speed v by applying a constant force of magnitude F over the stopping distance x, with F pointing opposite the direction of motion of the body.  The body will have acceleration

 

a = -F/m

 

Note a is negative.

 

The body comes to rest at a distance x.  By the laws of kinematics,

 

-v² = 2ax = 2(-F/m)x

 

v² = 2(F/m)x

 

x = (m/F) v²/2