Calculating Force of Friction: Newton's Law Applied in a Physics Experiment

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In a physics experiment, students calculate the force of friction exerted by a table to stop a paper cone, finding it to be 2.2 Newtons when the cone starts at 18 cm. A question arises about the force of friction when the cone starts from a height of 72 cm, with one student proposing a proportional calculation that results in 8.8 N. Despite using both proportional reasoning and energy calculations, the student's answer was marked incorrect, prompting a request for clarification on the mistake. The discussion highlights that the force of friction is ideally independent of speed and remains constant if the cone's weight and the table's flatness are unchanged. Understanding the setup and the relationship between the cone and the ball is crucial for accurate calculations.
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SIMPLE math-- Didn't I do this right?

In a physics experiment, students calculate the force of friction that a table exerts to stop a paper cone. When the ball starts at a height of 18 cm, the force of friction is 2.2 Newtons. What will be the force of friction if the ball starts from a height of 72 cm?

Wouldn't you set up a proportion and solve for x which is the force in Newtons? I did and got 8.8 N. Isn't that correct? For some reason, my homework is marked wrong and if I made a mistake, I want to know what it was.

(I also tried solving for their energies so that I could get work = the change in total energy so I could find the force using the work formula. I came up with 8.8 N with this approach also)
 
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I cannot picture this set-up. Where did the ball come from and how does it relate to the paper cone? How far did the cone travel?

Anyway, the force of friction is (ideally) independant of speed; if the cone remains a constant weight, and the table remains flat, then the force of friction will be the same no matter what happens.
 
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