Find the frictional force on the block

[katie beisel]

Homework Statement

When an 8.0 N force is exerted horizontally on a 10.0 kg block, the block’s acceleration across a level surface is 0.2 m/s2.

a. Find the coefficient of kinetic friction between the block and the surface.

b. Find the frictional force on the block.

c. Find the net force.

Homework Equations

F=ma?
Ff = mu x fN
fk = muk x fN

The Attempt at a Solution

i can't find the kinetic mu so I'm not sure how to get any of it

 

[Doc Al]

Try answering those three questions in reverse order. First: What's the net force on the block?

 

[SammyS]

Homework Statement

When an 8.0 N force is exerted horizontally on a 10.0 kg block, the block’s acceleration across a level surface is 0.2 m/s2.

a. Find the coefficient of kinetic friction between the block and the surface.

b. Find the frictional force on the block.

c. Find the net force.

Homework Equations

F=ma?
Ff = mu x fN
fk = muk x fN

The Attempt at a Solution

i can't find the kinetic mu so I'm not sure how to get any of it

Hello katie beisel. Welcome to PF.

In general, you need to show effort at solving/understanding the problem before we can help you.

For your problem, it may not be best to answer the questions in order: a, b, c.

Try answering any part you can.

 

[katie beisel]

Try answering those three questions in reverse order. First: What's the net force on the block?

ok i got that f net is 2 N by using Fnet = ma and i have that the force normal is 98 N

 

[Doc Al]

ok i got that f net is 2 N by using Fnet = ma and i have that the force normal is 98 N

Excellent! Part C is done.

Now work on B. Hint: Draw a free body diagram for the block.

 

[katie beisel]

Excellent! Part C is done.

Now work on B. Hint: Draw a free body diagram for the block.

would the frictional force be 6 N because the force push is 8 N and the net force is 2 N so 8 - 2 = 6?

 

[Doc Al]

would the frictional force be 6 N because the force push is 8 N and the net force is 2 N so 8 - 2 = 6?

Exactly right! B is done.

Keep going.

 

[katie beisel]

Exactly right! B is done.

Keep going.

is the frictional force and the kinetic friction the same?

 

[Doc Al]

is the frictional force and the kinetic friction the same?

Yes, since the block is sliding, the friction is kinetic friction.

 

[katie beisel]

Yes, since the block is sliding, the friction is kinetic friction.

ok so then the coefficient of kinetic friction is .06 and with sig figs its .1

 

[Doc Al]

ok so then the coefficient of kinetic friction is .06 and with sig figs its .1

.06 is already rounded to one sig fig. (Leading zeroes don't count.)

But good! You solved it.

Next time don't be shy about jumping in wherever you can. (And always show how you arrived at an answer.)