Calculation loss of energy due to friction?

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SUMMARY

The discussion centers on calculating the loss of energy due to friction in a physics problem involving work and kinetic energy. The user struggles with the equation Wnet = change in KE and the application of the work done by kinetic friction, represented as F(k) = F * d * cos(θ). The user attempts to derive the distance along a slope using the Pythagorean theorem, specifically calculating the slope distance as h * cos(15). However, the user finds their calculations do not match the expected answer from the computer system.

PREREQUISITES
  • Understanding of kinetic energy and work-energy principles
  • Familiarity with the concept of frictional forces, specifically kinetic friction
  • Knowledge of trigonometric functions, particularly cosine
  • Ability to apply the Pythagorean theorem in geometric calculations
NEXT STEPS
  • Study the derivation and application of the work-energy theorem in physics
  • Learn about the calculation of work done by frictional forces in various scenarios
  • Explore the use of trigonometry in physics problems, focusing on slope calculations
  • Review examples of similar physics problems involving energy loss due to friction
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and energy concepts, as well as educators seeking to clarify the application of work and energy principles in real-world scenarios.

okgo
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Homework Statement



http://i43.tinypic.com/i1bq1i.jpg
I need help with number 9

Homework Equations



Wnet=change in KE
Wnc=Change in Energy

The Attempt at a Solution


I haven't been able to get the answer marked by the computer.
I tried Fs(h*cos15)=.5mv^2-mgh
and that is way off the anwser
 
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okgo said:
I haven't been able to get the answer marked by the computer.
I tried Fs(h*cos15)=.5mv^2-mgh
and that is way off the anwser

Can you explain that equation? I don't understand what F and s are, or how you derived Fs(h*cos15).
 
sorry I meant that F(k) which is the force due to kinetic friction.
The equation for work is FDcos(theta). They gave use the height so I calculated the distance of the slope by Pythagorean theorem which gives cos(15)*the height.
 

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