Solving for F2 in the Turning Effect of Force Problem

[Muhammad Danish]

Homework Statement

Homework Equations

How will we find the perpendicular distance between the wall and the centre of mass of the slab? How will we calculate the total downward force exerted by the cables on the slab? I thought much over both the cases but was not able to find any solution. Your explanations will be seriously appreciable.

The Attempt at a Solution

Not able to make any attempt.[/B]

 

[kuruman]

Where do you think the centre of mass of the slab is located?

 

[Muhammad Danish]

Where do you think the centre of mass of the slab is located?

Between 2.5 m and 0.5 m

 

[Muhammad Danish]

Between 2.5 m and 0.5 m

At the top of the wall I mean..

 

[kuruman]

Between 2.5 m and 0.5 m

Can you be more specific? If I were to draw a line parallel to the long dimension of the concrete slab and perpendicular to the 3.0 m side, at what distance from where the cables are attached would I have to draw it so that it passes through the CM? The answer to this question is the answer to part (a). Have you done this much?

 

[Muhammad Danish]

At the top of the wall I mean..

Can you be more specific? If I were to draw a line parallel to the long dimension of the concrete slab and perpendicular to the 3.0 m side, at what distance from where the cables are attached would I have to draw it so that it passes through the CM? The answer to this question is the answer to part (a). Have you done this much?

Since the slab is 3.0 m wide, the center of mass should lie at 1.5 m from the side. Am I right?

 

[kuruman]

You are right. That's the answer to part (a). You can assume that the external force of gravity acts at the CM. This is a static equilibrium problem. Do you know how to proceed with problems of this kind?

 

[haruspex]

the center of mass should lie at 1.5 m from the side.

That's the answer to part (a)

Not quite... the question asks for the distance from the wall, not the side of the slab.

 

[kuruman]

Not quite... the question asks for the distance from the wall, not the side of the slab.

Yes, of course. Thanks for pointing this out.

 

[Muhammad Danish]

Not quite... the question asks for the distance from the wall, not the side of the slab.

Distance from the wall will be 1.5 - 0.5 = 1 ?

 

[kuruman]

Distance from the wall will be 1.5 - 0.5 = 1 ?

Yes, 1 m to be precise. Do you know where to go next in this static equilibrium problem?

 

[Muhammad Danish]

Yes, 1 m to be precise. Do you know where to go next in this static equilibrium problem?

To calculate downward force will we use the formula F1D1 = F2D2 ?

 

[kuruman]

To calculate downward force will we use the formula F1D1 = F2D2 ?

That looks about right for this case. What do you think F1, D1,F2 and D2 stand for? To use this equation you need numbers for three of them, the fourth one being the unknown. What are the three numbers?

 

[Muhammad Danish]

That looks about right for this case. What do you think F1, D1,F2 and D2 stand for? To use this equation you need numbers for three of them, the fourth one being the unknown. What are the three numbers?

They will be, F1= 18000 N, D1= 1 m and F2= ?, D2= 0.5 m ?

 

[jbriggs444]

They will be, F1= 18000 N, D1= 1 m and F2= ?, D2= 0.5 m ?

Yes. Now can you solve for F2?

 

[Muhammad Danish]

Yes. Now can you solve for F2?

Yes. Thanks.