# Pulling an object with a rope

1. Sep 22, 2009

### Nal101

1. The problem statement, all variables and given/known data

1) What is the net force on the block? (Cartesian Coordinate system)
2) What is the X component of the tension force on the block
3) What is the x-component of the force exerted by the floor on the block (the friction force)?
4) What is the y-component of the force exerted by the rope on the block?
5) What is the y-component of the force exerted by the Earth on the block?
6) What is the y-component of the force exerted by the floor on the block (sometimes called the "normal" force, because it is perpendicular to the floor)?

I pull on the rope with the force of 290 N
Mass of block is 22kg
Block moves at constant 1.3m/s
Angle of 35 degrees with the floor.

2. Relevant equations
p=mv
$$\Delta$$p=fnet$$\Delta$$t
ma = T - W
Ff = $$\mu$$N

3. The attempt at a solution
1) The net force will be the total force acting on the block, therefore in the X direction it would include the X component of the force I exert, and the Y component of the force I exert minus the force of gravity acting on the object.
Fx, me = 290 N * cos(35) = 237.55
Fy, me = 290 N * sin(35) = 166.34
Fgravity = mg = 215.6
Therefore <237.55, (166.34-215.6), 0>

2) Velocity is constant, so no acceleration, therefore T = W. Therefore, I dont know where to go with this.

3) I do not know mu, dont know how to solve for the force of friction.

4) Would this be equal to the force I exert on the rope multiplied by the sin of 35?
290sin(35) = 166.34

5) Already calculated this as well, Fg = mg = 215.6

6) Equal and opposite of Fg?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

Last edited: Sep 22, 2009
2. Sep 22, 2009

### kuruman

For question 1
What is the acceleration of the block?
How is the acceleration of the block related to the net force acting on it?

Once you get the answer to question 1 sorted out the rest should be easier to handle.

Clarification
Your problem statement does not give the mass of the block. What is it?

3. Sep 22, 2009

### Nal101

For question 1) Thanks! Of course, the net force is going to be 0 if there is no acceleration.

For mass of object, had a typo, what was originally mass of rope should be mass of block (22kg) the mass of rope/myself is supposed to be negligible, i apologize.

Figured out 2.

For 3, how do I calculate Ff without knowing $$\mu$$?

Figured out 4 & 5

For 6, is it the sum of earth + rope forces, multiplied by 1 (since its opposite direction)?

4. Sep 22, 2009

### kuruman

The sum of the horizontal components of the net force must be zero. Just balance the forces. "To the right" is positive, "to the left" is negative.

Figured out 4 & 5

The sum of the vertical components of the net force must be zero. "Up" is positive, "down" is negative.