Question

a 20 kg box is at rest on a level floor. the coefficient of static friction between the box and the floor is 0.35. hillary pushes against the box with a horizontal force of 50N. What is the force of statix friction on the box?

Answer 1

Answer:

$f = 50\,N$

Explanation:

Let assume that floor is horizontal. By definition, the force of friction is less or equal to the maximum static friction force. That is to say:

$f \leq \mu_{s}\cdot m \cdot g$

The maximum friction force is:

$f_{max} = 0.35\cdot (20\,kg)\cdot (9.807\,\frac{m}{s^{2}} )$

$f_{max} = 68.67\,N$

By applying Newton's law, the box has the following physical model:

$\Sigma F = F - f = 0$

Where:

$f = F$

Real friction is equal to 50 N, which is less than maximum friction force. Therefore, the static friction on the box is:

$f = 50\,N$