# A block of mass 100 kg is being moved steadily by pulling on a rope at

## Homework Statement

a block of mass 100 kg is being moved steadily by pulling on a rope attached to the block making an angle of 30 degree with the horizontal. if the tension of the rope is 120 N, what is the coefficient of friction?

T- Ff = ma
F= μR

## The Attempt at a Solution

R= mg cos x = 850 N
mg sin x = 490 N
a = 0, F= Ff
Ff = 120 N
F= μR
120= μ(850)
μ= 0.141
* ( answer given μ= 0.113. where is my mistake?)

PeterO
Homework Helper

## Homework Statement

a block of mass 100 kg is being moved steadily by pulling on a rope attached to the block making an angle of 30 degree with the horizontal. if the tension of the rope is 120 N, what is the coefficient of friction?

T- Ff = ma
F= μR

## The Attempt at a Solution

R= mg cos x = 850 N
mg sin x = 490 N
a = 0, F= Ff
Ff = 120 N
F= μR
120= μ(850)
μ= 0.141
* ( answer given μ= 0.113. where is my mistake?)

Not sure how/why you are doing any of those calculations. It always helps to say what you are about to do, then show the calculation.

Like for example:
Calculating force of gravity on the block : 100 x 9.8 = 980 N

Calculating vertical component of Tension: 120 x sin(30) = 60N

and what ever else you think is appropriate.

You then connect what you are calculating to give the answer you are after. A diagram can help.