If a 2 kg2kg object moving at 1 m/s1ms slows to a halt after moving 1/4 m14m, what is the coefficient of kinetic friction of the surface that the object was moving over?

1 Answer
Apr 12, 2016

0.200.20, rounded to second decimal place.

Explanation:

To find out the retardation due to kinetic friction let us use the equation
v^2-u^2=2asv2u2=2as,

where v,u,a,sv,u,a,s are the final velocity, initial velocity, acceleration and distance moved respectively.
0^2-1^2=2xxaxx1/40212=2×a×14
or a=-2ms^-2a=2ms2

Now Force F=m.aF=m.a
or Retarding force which is the force |F_f|=2xx2=4NFf=2×2=4N
We know that ths F_f=muxx"Normal Reaction"Ff=μ×Normal Reaction, where muμ is the coefficient of kinetic friction.

Assuming that the surface is a level surface, :. "Normal Reaction"=mg
Taking g=9.81ms^-2, we obtain
4=muxx2xx9.81, solving for mu
mu=4/(2xx9.81)=0.20, rounded to second decimal place.