I'm having a hard time understanding how to calculate tension. Help please?

[RainbowMop]

Now, I'm not going to ask anyone to do my assignments. I just want help understanding how to calculate tension so that I can complete my work by myself. I may give examples from my assignments, but I don't want anyone to just work it out and post answers - I want to understand.

I'm new to studying physics so I would appreciate simple explanations that I can understand(I'm in an intro course).

I've read that there isn't a formula for calculating tension and that tension is just a force. Right now I'm working with problems that involve a string under ideal conditions.

Ex. The diagram is displayed as a right triangle with theta in the lower left. Two blocks are connected by a string and tied to a wall. They look like this along the hypotenuse; []-[]-
The mass of both blocks and the value for theta are given. I need to (i)calculate the tension of the string connecting the two blocks, and (ii)the tension in the string tied to a wall.

I first tried to find the x and y components(as it is set up to look like a vector and we have been doing this a lot in class). For the magnitude I added the masses of the blocks, but I don't know if that is right. Then I used cos(theta)*magnitude for x-component, and sin(theta)*magnitude for y-component. Honestly, I'm not too sure if I even need to find the vector components.

I also know that F=m*a. The mass(for part (i)) would be the mass of both blocks and the acceleration would be g=9.81m/s^2?

Basically I've tried this several different ways and I am getting all my tension problems wrong. This is because I don't fully understand the concept of calculating tension and I would appreciate some help.

Thanks.

 

[Doc Al]

Please post a diagram so we can understand exactly what you are asked to find. (I'll move this to Intro Physics, where it belongs.)

I presume this is a statics problem. The blocks are in equilibrium, thus ΣF = 0 for each block. (In a statics problem the acceleration is zero, not 9.8 m/s^2.)

Start by identifying the forces on each block and drawing free body diagrams. Then you can come up with equations for the x and y components of the forces.

 

[RainbowMop]

Please post a diagram so we can understand exactly what you are asked to find. (I'll move this to Intro Physics, where it belongs.)

I presume this is a statics problem. The blocks are in equilibrium, thus ΣF = 0 for each block. (In a statics problem the acceleration is zero, not 9.8 m/s^2.)

Start by identifying the forces on each block and drawing free body diagrams. Then you can come up with equations for the x and y components of the forces.

I can't post a diagram.

 

[ashishsinghal]

why is that so?

 

[Doc Al]

I can't post a diagram.

Why not?

Then at least describe how the blocks and the string are connect in more detail. Is the arrangement: wall - string1 - block1 - string2 - block2 - string3 - wall? Is the string connecting the two blocks horizontal?

But even if you don't you can still use the hints I gave earlier.

 

[RainbowMop]

why is that so?

I can't copy and paste the picture, I can't link you to it...

Nevermind if it's too much trouble.

 

[2milehi]

Open up Paint, draw your item, save to computer, create account on photobucket.com, upload image, paste link, and make everything easier.

 

[RainbowMop]

Too much trouble nevermind.

 

[Doc Al]

Without a diagram, you'll at least have to describe the setup as I suggested in post #5. That should be easy to do.