(adsbygoogle = window.adsbygoogle || []).push({}); AP Physics Question about friction???

1. The problem statement, all variables and given/known data

Please explain everything through... I'm so lost :(

Mass B is on top of Mass A which is on top of the floor.

B=2kg, A=4kg, gravity assumed to be 10m/s^2

Coefficient of friction between B and A is 0.2 kinetic, 0.4 static

Coefficient between A and the floor is 0.

A force is solely being applied to B.

1. Make a FBD of each of the two masses!

2. Max force that will allow them to move as one?

3. Acceleration of each mass if F = 40N?

4. Acceleration of each mass if the coefficient of friction (static and kinetic) between the floor and A is 0.2?

Questions 5-7 is assumed that a force is solely being applied to A.

5. Max force that will allow them to move as one?

6. Acceleration of each mass if F = 40N

7. What is the acceleration of each mass if the coefficients between A and the floor is 0.2?

Questions 8-11 is assumed the same, with the force solely being applied to A, but the static and kinetic friction is 0.4 and 0.3 respectively between all surfaces.

8. Biggest Force that will allow them to move as one?

9. Magnitude and direction of force of friction on each mass in #8?

10. Acceleration of each mass if the force is 10N? 30N? 60N?

11. Magnitude and direction of force of friction on each mass in #10 in each case?

I'm sure that by answering a couple of them I'll understand the rest, but I don't know how to get started... everytime I attempt this, I always get the wrong answer...

2. Relevant equations

F=MA

Friction=μk/s x Fn

mass of A/mass of B = acceleration of B/ acceleration of A

???

3. The attempt at a solution

I really don't know...

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# Homework Help: AP Physics Question about friction?

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