While I am asking more than one question in this thread they are all small concept tests that you can answer with a yes or no, and is all related to me understanding kinetic and static friction.
What I know:
Force of friction = Mu*N.
Static friction = The friction that keeps the object from moving.
Kinetic friction = The friction that is pushing against the motion of the object.
What I don't think I understand/or what I think is the problem:
I don't think I know what Mu(s), and Mu(k) really are, and I might be mixing them (or know if they are even one).
What I don't understand:
According to a physics teacher the force of static friction /= Mu(s)*N except sometimes.
How is that?
Qustion number 2 in the picture. http://gyazo.com/ad3f358af9f36c1ddcb2e8b4d93188c2
If an object is standing still it's static so how can the answer to the question be false?
The same box as in question 1. Question 2. http://gyazo.com/b5869084b618e96e6a1fe491274295f4 The answer is yes.
I think this one is yes because for the block to move the tension in the string needs to be bigger than the maximum static friction.
The same box as in question 1. Question 3. http://gyazo.com/52af207d0c0b55453cc200b875d3e179
Question 4. http://gyazo.com/52af207d0c0b55453cc200b875d3e179 It must be moving right? But not accelerate.