Question involving Newton's laws

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Homework Help Overview

The problem involves a solid uniform ball on a tilted ramp, requiring the determination of the normal force exerted by the ramp and the tension in a wire holding the ball in place. The ramp is smooth and inclined at an angle of 35.0°.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to use trigonometric relationships to find the normal force, expressing it in terms of mg. Some participants question the necessity of knowing the mass and the implications of the problem's constraints.

Discussion Status

Participants are exploring different interpretations of the problem, particularly regarding the relationship between the normal force and the weight of the ball. There is acknowledgment of a discrepancy between the original poster's calculations and the expected answer, leading to further inquiry into the setup and assumptions.

Contextual Notes

The problem does not provide a specific mass for the ball, which is noted as a potential limitation in verifying the calculations. The original poster's confusion about the relationship between the angles and forces is also highlighted.

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Homework Statement


A horizontal wire holds a solid uniform ball of mass m in place on a tilted ramp that rises 35.0° above the horizontal. The surface of this ramp is perfectly smooth, and the wire is directed away from the center of the ball.(a) How hard does the surface of the ramp push
on the ball? (b) What is the tension in the wire?


Homework Equations





The Attempt at a Solution


I drew a picture and made a triangle with the normal force as one side, the ramp as one side, and the weight as the hypotenuse. I believe the angle between the ramp and the hypotenuse is 55 degrees. That would mean sin(55) = N/mg and that N = mg*sin(55). This is equivalent to approximately 0.82mg. However, the answer I have for this problem is 1.22mg and 1/sin(55) equals 1.22. I am trying to figure out what I am doing wrong here. Any help would be appreciated!
 
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I am confused as to what you are looking for. You found an answer where you listed your attempt, but you didn't provide a mass to use. Otherwise:

FN = mgsinθ

However, without the knowing the mass, it would be hard to find out where you went wrong.
 
Thanks for the reply.
I didn't list a mass because the question didn't provide one. The answer is expected to be in terms of mg. The answer is supposed to be 1.22mg, but I am getting an answer of .82mg.
 
Last edited:
Strangely enough, I had a problem like this in my physics course a few weeks ago that took me a while to actually understand. I'm not sure if I can explain it, but the way that I understand it is that when on a plane, FN is represented by a leg of the triangle, and gravity by the hypotenuse. In order to solve this triangle, you must divide by the sine.
 

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