Question

A 6.80 kg block of wood has a static coefficient of 0.340 and a kinetic coefficient of friction of 0.170 between it and a desk.

Calculate the maximum force of static friction.

Calculate the force of kinetic friction (i.e. find Ff).

If the block is at rest, and I exert a force of 27.0 N to make it move, does it slide? Why or why not? Explain your answer with numbers and words.

If the block is at rest, and I exert a force of 20.0 N to make it move, does it slide? Why or why not? Explain your answer with numbers and words.

Any help is appreciated. If the question is solved, could you provide the steps so I can learn please :)

Answer 1

1.
`F=22.66 \ N`

2.
`F=11.33 \ N`

3. Yes

4. No

Step-by-step explanation:

1. Max force of static friction

We use the formula shown below:

`F=\mu mg`

Where

`\mu` is coefficient of static friction

m is mass

g is acceleration due to gravity (it is 9.8)

Now, calculating:

`F=\mu mg\\F=(0.34)(6.80)(9.8)\\F=22.66 \ N`

2. Force of Kinetic Friction

We use the formula shown below:

`F=\mu mg`

Where the variables are same as defined above, but this time
`\mu` would be coefficient of kinetic friction

We calculate:

`F=\mu mg\\F=(0.17)(6.8)(9.8)\\F=11.33 \ N`

3.

Is the force GREATER than the max frictional force? If Yes, it will move.

The max frictional force is 22.66 and YES, the force of 27 N is greater, thus it will slide.

4.

The same principle holds as the previous question. If the force is greater than max frictional force, which is 22.66, it will slide. Or else, it wont!

20 N < 22.66 N

Thus, it won't slide.