# Help with a tension problem

• danielab87
In summary, the tension in the rope is equal to the sum of the normal forces on each block multiplied by the block's acceleration.

#### danielab87

hi i cannot seem to figure this problem out at all. any help is appreciated.

A 30 kg block (M1) is placed on a frictionless plane that inclines at a 30° angle with respect to the surface of Earth. This block is connected to another 20 kg block (M2) via a weightless rope over a frictionless, ideal pulley. The second block is hanging vertically, as shown in the figure. What is the tension of the rope?

thanks

#### Attachments

• image.gif
2.2 KB · Views: 349
What are your thoughts on the question? If a mass isn't moving, what can you say about the resultant force on it?

i believe that if the mass isn't moving, its net force is 0 because there is no acceleration. I'm just not sure what to use as my equations. this type of problem has always confused me for whatever reason.

draw a force diagram for each blocks to see what forces are acting on them. As you said, the sum of these forces must be 0 because the blocks aren't moving.

ok well on mass 1 i got the normal force going up, mgcos30 going down, tension going to the right and mgsin30 going left. on mass 2 i got tension up and mg down. so this would mean that T=mgsin30 or T=mg, but those are not right. there's something else that i am not seeing

yeah actually i don't see how the blocks aren't moving because they should with those given quantities. problem was a little ambiguous on whether or not the blocks were moving. instead of making the sum of the forces equal to 0, make it equal to what it should be when the blocks are moving, which is mass times the block's acceleration.

My advice is to assume acceleration. Let us say that M1 is sliding down the incline plane, so write your equation based off of that. If it turns out that M1 is going up, it shouldn't really matter.

ok would the equation be ma+mgsin30=T? I'm not entirely sure. and then how do i know what the acceleration is? thanks

yes , I think your equation is right.
but
i want ask futher question , is "a" and "g" in the same direction?
I think M2g+M1gsin30=T would be better.

or I think in a wrong way?

## What is a tension problem?

A tension problem is a type of physics problem that involves calculating the force or tension in a system, usually caused by the pulling or stretching of an object.

## How do I solve a tension problem?

To solve a tension problem, you will need to identify the forces acting on the system, determine the direction of the forces, and use equations such as Newton's 2nd Law or the equations for equilibrium to calculate the tension.

## What are some common examples of tension problems?

Some common examples of tension problems include determining the tension in a rope holding up a hanging object, calculating the tension in a cable supporting a bridge, or finding the tension in a rubber band being stretched.

## What are some tips for solving tension problems?

One tip for solving tension problems is to draw a free-body diagram to identify all the forces acting on the system. Another tip is to carefully label and keep track of the direction and magnitude of each force.

## How can I check if my answer to a tension problem is correct?

You can check your answer by plugging it back into the equations you used to solve the problem and making sure it satisfies all the given conditions and equations. You can also try solving the problem using a different method or approach to see if you get the same answer.