A tired worker pushes a heavy (100-kg) crate that is resting on a thick pile carpet. The coefficients of static and kinetic friction are 0.6 and 0.4, respectively. The worker pushes with a horizontal force of 490 N. The frictional force exerted by the surface is

The friction force exerted by the surface is 490 newtons.

Explanation:

From Physics, we remember that static friction force (), measured in newtons, for a particle on a horizontal surface is represented by the following inequation:

(Eq. 1)

Where:

- Static coefficient of friction, dimensionless.

- Mass of the crate, measured in kilograms.

- Gravitational acceleration, measured in meters per square second.

If , then crate will experiment an imminent motion. The maximum static friction force is:  (, , )

From Newton's Laws we get that current force of friction as reaction to the pulling force done by the worker on the crate is:

(Eq. 2)

Where:

- Horizontal force done by the worker, measured in newtons.

- Static friction force, measured in newtons.

If , then the static friction force exerted by the surface is:

Given that , the crate does not change its state of motion. The friction force exerted by the surface is 490 newtons.  

the journeys of marquette, joliet and la salle a) new france expand.

all three of these explorers explored the midwest and the area around the great lakes, which they subsequently claimed for france.

this was a big portion of territory and expanded new france which before then only consisted of quebec province in northeastern canada