Solving Friction/Energy Homework Problem

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Homework Help Overview

The problem involves a 3.00 kg mass sliding up a ramp at an angle of 28 degrees, connected to a second mass of 3.25 kg via a frictionless pulley. The coefficient of kinetic friction is given as 0.285, and the task is to find the acceleration of the first mass, its kinetic energy after traveling 25 cm, and the work done on it during that distance.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the calculation of the normal force and the force of friction, with one participant questioning the initial calculations and suggesting the need for a free body diagram to analyze the forces acting on the masses. There is mention of separating gravitational forces into components and the need for multiple equations to solve for acceleration.

Discussion Status

The discussion is ongoing, with participants providing feedback on calculations and suggesting the use of diagrams to clarify the problem setup. There is a collaborative effort to refine the understanding of the forces involved, but no consensus has been reached on the solution.

Contextual Notes

Participants note the importance of accurately representing the forces acting on the masses and the potential ambiguity regarding the location of the second mass in the problem setup.

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Homework Statement


A 3.00 kg mass, m1, slides up a ramp. The angle for the ramp is 28*. The 3.00 kg mass is connected to a second mass, m2, of 3.25 kg by a light string with a frictionless pulley. Coeeficient of kinetic friction is 0.285. Find the acceleration of m1, the kinetic energy of m1 after it has traveled 25 cm up the ramp, and the work done on m1 to moce it the 25 cm.

Homework Equations


Fr = μN
EK = (1/2)mv^2
Besides this I don't know

The Attempt at a Solution


Well the friction would be .285 times the normal force of m1, which I think is 26.49. So I got the force of friction is 7.55 N. Then I subtracted 7.55 from 9.81, the acceleration on m2. But I don't think any of this is right. Help?
 
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Your normal force looks okay, though I got the slightly different 26.0 N.
In the ramp problem, you really have to have a diagram like this:
ramp.jpg

The mg force down needs to be separated into a part perpendicular to the ramp (N) and a part parallel to the ramp. Then you forget all about the mg and just use the components. So far two forces on the 3 kg mass - the friction and the parallel part of gravity. You also have the the tension on the string. Write that the sum of those forces is equal to ma.

The location of the 2nd mass is unclear. But you'll need another F = ma equation for that. With two equations you should be able to eliminate the Tension and find the acceleration. Please show your work so it is easy to tell how you got answers.
 
Nice job! The free body diagram and F = ma for the second mass should be easy.
 

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