# An object with a mass of # 14 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

#### Answer:

The surface's coefficient of static friction, in this case, will be 0.0051, approximately.

#### Explanation:

Since the object is lying still on the surface, it is in equilibrium and, therefore, the net force in it must equal zero:

Since it is placed by a horizontal spring, the friction force,

Now, since the displacement

Now, from Equation (1),

Now, since

Since in this case the normal force equals the object's weight, then: