Solving Force Problems: Finding F with Trig and Components

In summary, the conversation revolved around solving force problems, specifically in relation to a sphere suspended from a cord. The individual is struggling to find the magnitude of the push and the tension in the cord, despite understanding the concept of using the equation F=ma. They mention trying to use trigonometry but are stuck. They also mention finding the horizontal and vertical components of tension and determining the net forces acting in each direction.
  • #1
rt525600
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I'm having a lot of trouble solving force problems even though I understand the concepts (or, at least I think I do). This is a specific example:

A sphere of mass 3.0 x E-4 kg is suspended from a cord. A steady horizontal breeze pushes the sphere so that the cord makes an angle of 34 degrees with the vertical when at rest.

Find the a) magnitude of that push and b) the tension in the cord.


The only equation that I know of to solve force problems is F=ma. We have m.


I think that I can use trig to find F, but I can't figure out how.
I tried to solve for F by using components: I found the downward force by finding mg (= -2.94 E-3). I'm kind of stuck now. Any suggestions?
 
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  • #2
Divide the tension in the cord into 2 compoennts... horizontal and vertical. If T is the tension, what is the horizontal component of tension? what is the vertical component of tension?

net force in x direction = max... however ax = 0

net force in the x direction = 0

same way

net force in the y direction = 0

What are the forces acting vertically... what are the forces acting horizontally?
 
  • #3


First of all, it is important to note that in order to solve force problems, you need to consider all the forces acting on an object and their respective directions. In this specific example, the forces acting on the sphere are the weight (mg) and the horizontal push from the breeze (F).

To find the magnitude of the push (F), you can use trigonometry to solve for the horizontal component of this force. Since the cord makes an angle of 34 degrees with the vertical, the horizontal component of the force (Fcos34) will be equal to the magnitude of the push. You can then use this value in the equation F=ma, where m is the mass of the sphere and a is the acceleration in the horizontal direction (which is 0 since the sphere is at rest).

To find the tension in the cord, you need to consider the vertical forces acting on the sphere. The tension in the cord (T) will be equal to the vertical component of the weight (mgcos34) plus the vertical component of the push (Fsin34). You can then use this value in the equation T=ma, where m is the mass of the sphere and a is the acceleration in the vertical direction (which is also 0 since the sphere is at rest).

It is important to carefully consider all the forces and their respective components in order to solve force problems accurately. I would suggest practicing with different examples and seeking help from a teacher or tutor if necessary. Good luck!
 

FAQ: Solving Force Problems: Finding F with Trig and Components

How do you find the magnitude of a force using trigonometry and components?

To find the magnitude of a force using trigonometry and components, you need to use the Pythagorean theorem. This involves squaring the x and y components of the force, adding them together, and then taking the square root of the sum. This will give you the magnitude of the force.

What is the difference between a force's components and its magnitude?

A force's components refer to the force's individual vectors in the x and y directions. These components can be used to find the force's overall magnitude using trigonometry. The magnitude of a force, on the other hand, refers to the overall strength or size of the force.

Can you use trigonometry to find the direction of a force?

Yes, you can use trigonometry to find the direction of a force. By using inverse trigonometric functions, you can find the angle of a force's components and use that to determine the overall direction of the force.

How do you solve force problems involving angles and components?

To solve force problems involving angles and components, you need to break the force into its x and y components, find the magnitude of each component using trigonometry, and then use the Pythagorean theorem to find the overall magnitude of the force. Finally, you can use inverse trigonometric functions to find the angle or direction of the force.

What are some common mistakes when solving force problems with trigonometry and components?

One common mistake is forgetting to convert angles to the correct units (usually radians) before using trigonometric functions. Another mistake is not carefully labeling components and angles, which can lead to confusion and incorrect calculations. It is also important to use the correct formulas and pay attention to signs (+ or -) when solving for components and angles.

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