A car of mass m travelling with a velocity v comes to rest over a distance d in time t. The constant frictional force acting on the car while it is braking is found using:
Newton's Second Law: F=maa=v-u/tUsing SUVAT equations: v2= u2+2asv (final velocity)=0 u(inital velocity)= v s=d Rearranging gives: -v2=2ad a=-v2/2d Therefore F= -mv2/2dNegative sign suggests the car is slowing down (negative acceleration)
