Question

2. A 2.0 kg block rests on a level surface. The coefficient of static friction is µs = 0.60, and the coefficient of kinetic friction is µk = 0.40. A horizontal force, F, is applied to the block. As F is increased, the block begins moving. Describe how the force of friction varies as F increases from the moment the block is at rest to when it begins moving. Indicate how you could determine the force of friction at each value of F―before the block starts moving, at the point it starts moving, and after it is moving. Show your work. Just show me how to do it like the formulas

Answer 1

okay tell me what is nu(s) and nu(k)?

Answer 2

I think that the rock starts to move when the guiding force \(F\) is equal to friction force:
\(\large F=\mu_s Mg\), where \(M\) is the mass of the rock

Answer 3

oops.. I meant block not rock

Answer 4

furthermore, the static friction force is a variable force, and its maximum magnitude \(R\) is:
\[R = {\mu _S}Mg\]

Answer 5

where \(\mu_S\) is the static friction coefficient

Answer 6

@Michele_Laino So then where would µk = 0.40 be needed?

Answer 7

When the block will b moving u will use meu k=0.40

Answer 8

Thank you all, but I still don't get it... #Iamreallybadatphysics

Answer 9

after that the motion of the block is started, we have to use the kinetic friction coefficient \(\mu_k\) in place of the static friction coefficient

Answer 10

Thanks guys you helped so much!