# An object with a mass of # 18 kg# is lying on a surface and is compressing a horizontal spring by #60 cm#. If the spring's constant is # 8 (kg)/s^2#, what is the minimum value of the surface's coefficient of static friction?

##### 1 Answer

#### Answer:

#### Explanation:

The friction force is dependent on 2 factors.

The coefficient of static friction(

In the above question, the body is attached to a compressed spring, and hence the spring exerts some force on the body. This force is given as

(Note that

Now, we know that the body is at rest because no force is acting on it, or the vectorial sum of the forces is zero. Which means that the spring force is being equalized by the force of friction.

Now we know that the force of friction is given by

where

We know that the body is on a horizontal platform without angle, so

Since the force of friction and force of spring are equal (opposite in direction remind you), we get

Substituting the values, you'll get the above given answer.