Forces experiment. Needing to find vector sum of the tensions in string.

• tatsalez
In summary, Matt's physics class is confusing him. He doesn't know how to do the vector sum of the tensions, and he's not sure if what he's doing is correct. He needs help from someone who knows more about physics.
tatsalez

Homework Statement

The question is: find the vector sum of the tensions in the strings; remember to multiply each mass by g. In theory, this sum should be the zero vector.

We had to use pulleys and weights and find the angle and mass of a third hanger to make a ring in the middle of a plate in equilibrium.

For one example: We placed .200kg on a hanger at 30 degrees and 120 degrees. For equilibrium we needed a hanger at 255 degrees with .275kg It says we need to find the vector sum of the tensions.

Our teacher didn't tell us how to go about doing so. We thought we would use fnetx and fnety Something like: .200(9.8)cos(30) + .200(9.8)cos(120) + .275(9.8)cos(255) = Fnetx

Then do it for Fnety with sin.

Is this correct? A lab partner thought this was right. I'm completely lost in my physics 151 class. I know vector sum is when you add the vectors, but are these considered vectors?

Any help I would be grateful for!

Thanks,
Matt

As for vectors: Vectors have magnitude and direction. This is opposed to scalars, which have only magnitude. For example, tension, a force, is a vector. Mass, however, has no direction and is therefore scalar.

You have the right idea using trig to find the x and y components. Did you take into consideration all of the tension on the string (tension you created with the mass and tension from the object you're lifting)? Are you using a good reference angle? I like to use the positive x-direction for 0 degrees. Did you draw a free-body diagram?

I hope this helps.

I don't believe we need to use tensions. we used a force plate and just had to make the third pulley and its hanger/mass into equilibrium. Thats gives 3 degree's and 3 masses's. for each problem which there are 5 different sets. So we just with fnetx and fnety for the 3 degree's and 3 masses. I believe the result is suppose to come out near 0 right? we all got close like .02 -.06 etc

1. What is the purpose of conducting a forces experiment?

The purpose of conducting a forces experiment is to understand and analyze the effects of different forces on an object. This can help in predicting the motion and behavior of objects in various situations.

2. How do you find the vector sum of tensions in a string?

To find the vector sum of tensions in a string, you need to first determine the individual tensions acting on the string. Then, you can use vector addition to find the resultant tension, taking into account the direction and magnitude of each tension.

3. What are some common tools used in a forces experiment?

Some common tools used in a forces experiment include force sensors, pulleys, spring scales, and weights. These tools help in measuring and applying different forces to objects during the experiment.

4. How do you ensure accuracy in a forces experiment?

To ensure accuracy in a forces experiment, it is important to use precise and calibrated instruments, minimize external factors that may affect the results, and repeat the experiment multiple times to get consistent results. It is also crucial to record and analyze the data carefully.

5. What are some real-life applications of understanding vector sums of tensions?

Understanding vector sums of tensions is crucial in many real-life applications, such as designing bridges and buildings, calculating the force needed for a rocket to take off, and determining the stress and strain on different parts of a structure. It is also important in sports, such as calculating the force needed to hit a baseball or kick a soccer ball with a certain velocity and direction.

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