Finding Tension in a String Holding a Meter Stick Against a Wall

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In summary, the problem involves a 0.13 kg meter stick being held perpendicular to a wall by a 2.7 m string. The tension in the string can be found using the formula T=mg/sin(theta). However, this formula does not take into account other forces, such as the wall's horizontal and vertical forces. The tension in a shorter 2.0 m string can also be found using this formula.
  • #1
proace360
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Homework Statement


A 0.13 kg meter stick is held perpendicular to a wall by a 2.7 m string going from the wall to the far end of the stick.
(a) Find the tension in the string.
(b) If a shorter string is used, will its tension be greater than, less than, or the same as that found in part (a)?
(c) Find the tension in a 2.0 m string.


Homework Equations



Torque=Nr?

The Attempt at a Solution


I discovered the angle to be 68.38 degrees, and I thought that, since the y-component of the force cancels out mg, T=mg/sin(theta). Why is it wrong?
 
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  • #2
The string tension is not the only force (besides the weight) acting on the stick.
 
  • #3
I know that the wall exerts a horizontal force, but that doesn't matter in the Fy equation.
 
  • #4
But the vertical force it exerts does.
 
  • #5
wait... how does it exert a vertical force? Is there a friction force?
 
  • #6
proace360 said:
wait... how does it exert a vertical force? Is there a friction force?
There better be. But you need not worry about the wall force to solve this problem.
 

1. How do you use a meterstick against a wall?

To use a meterstick against a wall, place the meterstick vertically against the wall with the end touching the ground. Make sure the meterstick is straight and not tilted. Then, read the measurement at the top of the meterstick where it meets the wall. This will give you the height of the wall.

2. What is the purpose of using a meterstick against a wall?

A meterstick against a wall is commonly used to measure the height of objects, such as walls, doors, or bookshelves. It is a simple and accurate way to determine the height of an object.

3. How do you read measurements on a meterstick?

Metersticks are typically marked with both centimeters and millimeters. To read a measurement on a meterstick, look at the number on the meterstick that lines up with the edge of the object being measured. If the object falls between two numbers, estimate the measurement to the closest millimeter.

4. Can you use a meterstick against a wall to measure distances?

Technically, yes, you can use a meterstick against a wall to measure distances. However, this method may not be as accurate as using a measuring tape or ruler. Metersticks are best used for measuring heights rather than lengths or distances.

5. Are there different types of metersticks for different purposes?

Yes, there are different types of metersticks for different purposes. Some metersticks are made of wood, while others are made of metal or plastic. Some metersticks are also marked with both inches and centimeters, making them more versatile for different types of measurements.

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