• CHALLENGE You need to move a 105-kg sofa to a different location in the room. It takes a 403-N force to start the sofa moving. What is the coefficient of static friction
between the sofa and the carpet?

μ = 0.391

Explanation:

The friction force is defined as the product of the coefficient of friction by the normal force. In this way, we have the following equation.

F = μ*N

Where:

F = friction force = 403 [N]

μ = static coefficient

N = Normal force [N]

And the normal force of a body lying on a horizontal surface can be calculated by means of the product of mass by gravitational acceleration.

Now we can clear the  static coefficient

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

snell's law

refractve index = sin incidence / sin refraction