An object with a mass of # 1 kg# is lying still on a surface and is compressing a horizontal spring by #1 m#. If the spring's constant is # 7 (kg)/s^2#, what is the minimum value of the surface's coefficient of static friction?

1 Answer
Mar 6, 2016

Force F required to compress a spring by x unit is
#F=k*x#,where k = force constant.
Here x =1m
#k=#7kgs^-2
hence Force exerted on the object of mass 1 kg is #F=7(kg)/s^2*1m=7(kg*m)/s^2=7N#
This force is balanced by the then static frictional force as it is self adjusting one,

So the minimum value of the coefficient of static frictions
#mu_s=F/N#,where N is the normal reaction exerted on the body by the floor. Here #N =mg=1*9.8N=9.8N#
So
#mu_s=F/N=7/9.8=0.71#