Friction & Coefficient: Overcoming Initial Restitution

[goomer]

Say a person is pushing a box. The box starts at rest but eventually moves because the person's act of pushing on the box overcomes the friction between the box and the ground. Is the force of friction decreased after the person overcame the initial friction? Does the coefficient of friction ever change in the system?

 

[gneill]

Say a person is pushing a box. The box starts at rest but eventually moves because the person's act of pushing on the box overcomes the friction between the box and the ground. Is the force of friction decreased after the person overcame the initial friction? Does the coefficient of friction ever change in the system?

Look up "static friction" and "dynamic friction". They usually have different values, and for a given interface static friction is generally greater than dynamic friction. (Which is why it's better that your car brakes don't lock the tires for the shortest stopping distance)