Solve Work Energy Power Homework with Friction Present

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SUMMARY

The discussion centers on the application of the work-energy theorem in scenarios involving friction. The user seeks clarification on when to add or subtract frictional work in calculations. It is established that when moving up a ramp, the work done by friction should be added, while moving down a ramp requires subtracting frictional work. The user specifically requests equations to effectively handle these situations, indicating a need for clear guidelines on incorporating friction in energy calculations.

PREREQUISITES
  • Understanding of the work-energy theorem
  • Knowledge of frictional forces and their direction
  • Familiarity with basic physics equations involving force and displacement
  • Concept of conservation of energy in mechanical systems
NEXT STEPS
  • Study the work-energy theorem in detail
  • Learn how to calculate work done by friction in various scenarios
  • Explore examples of energy conservation with friction in physics problems
  • Review the equations of motion for objects on inclined planes
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and energy conservation, as well as educators looking for clear explanations of friction's role in work-energy calculations.

GrandMaster87
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Homework Statement


Hi Guys

I have a problem when working with conservation of energy and work energy theorem. I have a problem when friction is present in the system.

I don't know when to add the friction to get the total work done or when to minus the friction to find work done.

Will someone be able to help me out?

1. Let's say someone is going UP a ramb and friction is present.
2. a skier is going down a slope and friction is present along the course.
3. a person is going down a slope , friction present and they ask you to find the skiers velocity at the bottom.
4. a car is moving up a slope and friction is present and you need to work out the velocity at the top

My Answer.

When someone is going up a ramp we add the work done by friction to obtain the work done.

2. when someone is going down a ramp we minus the friction to find work done.

Im not to sure about this. In my exam i lost the 13 marks for this question. Can someone just maybe give me some equations to use when friction is present for the different situations because when friction is present i get really confused.

Thanks a lot for reading..looking forward to your replies
 
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Work done = F*d*cosθ.
Frictional always acts in the opposite direction to the displacement.
 

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