Q.In a physics experiment,two balls A and B,of mass 4m and 3m respectively,are travelling towards one another on a straight horizontal track.Both balls are travelling with a speed of 2 ms-1 immediately before they collide.
As a result of the impact,A is brought to rest and the direction of motion of B is reversed.
Modelling the track as smooth and the balls as particles,
a)find the speed of B immediately after the collision
A student notices that after the collision ,B comes to rest 0.2m from A.
B)Show that the coefficient of friction between B and the track is 0.113,correct to 3 decimal places.
This is from Mechanics Solomon Papers
I don't understand how to do no-b.Our teacher first used F=ma and then used F=uR(meow R,formula for maximum frictional force)then wrote ma=uR then tried to find the things.Can anyone explain me what to do exactly?