Question

A bedroom bureau with a mass of 45 kg, including drawers and clothing, rests on the floor. (a) If the coefficient of static friction between the bureau and the floor is 0.45, what is the magnitude of the minimum horizontal force that a person must apply to start the bureau moving

Answer 1

Answer: the minimal force that you need to apply to move the bureau is F = 198.45N

Explanation:

If you want to move an object, you need to apply a force that is bigger than the force of the statical friction.

The force of statical friction can be written as.

Ff = k*N

where k is the coefficient of static friction, in this case, k = 0.45, and N is the normal force between the object and the surface.

In this case, the normal force is the weight of the bedroom bureau, this is:

N = m*g = 45kg*9.8m/s^2 = 441N

Then the force is:

Fr = 0.45*441N = 198.45N

This means that the minimal force that you need to apply to move the bureau is F = 198.45N

and after this point, the force of friction will work wit the kinetic coefficient of friction, that usually is smaller than the statical one.