Question

The coefficient of static friction for between a 9-newton wooden blok an a level surface is 0.4 and the coefficient of kinetic friction is 0.3. Determine the force of friction, on the block if you pull it horizontally with the follow force. Specify if the friction is static or kinetic:

(a) 0-N
(b)2-N
(c)4-N
(d)6-N
(e)8-N

how do i do this

Answer 1

@Data_LG2

Answer 2

Fg=9N
µs=0.4
µk=0.3
Ff=?

Ff is given by the formula \(\Large Ff=\frac{\mu}{F_n}\)

Answer 3

oops made a mistake!
it should be \(F_f = \mu \times F_n\)

Answer 4

so i have 0.3*9=2.7

Answer 5

what does it mean when the question says "with the follow force" (i just want to make sure that i'm telling you the right method)

Answer 6

i'm not sure maybe with the following force they mean 9-newton

Answer 7

oh i should get 29.4 not 2.7

Answer 8

okay. Since the object is \(resting\) on a level surface before you pull it, you should use the \(maximum\) coefficient of static friction and not the coefficient of kinetic friction because you have to overcome the \(maximum\) coefficient of static friction before making the block move

Answer 9

so instead of using 0.3 as your \(\mu\), you should use 0.4 because it is the \(\mu _{max}\)

Answer 10

*\(\Large \mu _{s_{max}}\)

Answer 11

okay so when i do that i should have .4*98=39.2

Answer 12

where did you get 98?

Fg=9N
Fg=Fn
therefore Fn=9N

Answer 13

gravity?

Answer 14

soi should do .4*9=3.6

Answer 15

Fn is the normal force
Fg is the force of gravity

gravitational field strength(g) is different from the force of gravity(Fg)
Fg=mg
but since the question already provided you the weight of the block or the Fg, you dont have to calculate for Fg and no need to use the value of g.

Yes that will be right. Round your answer and you'll find it in one of your choices :)

Gtg , goodnight!

Answer 16

thanks