Slope of an Energy with Friction Graph?

In summary, the conversation discusses the effects of friction on the slope and y-intercept of a graph representing the relationship between work (W) and potential energy (PE) and kinetic energy (KE). It is concluded that if friction is included in the calculation of work, there will be no change in the graph. However, if friction is not included, there will be a decrease in both the PE+KE of the particle and the y-intercept.
  • #1
Londoncalling
11
0

Homework Statement


An object is pulled at a constant F. KE0+PE0=0, so W=PE+KE. If there were no friction, the slope of a graph (KE+PE=Y-axis, W=X-axis) would be 1 and the y-intercept would be 0. What would the addition of friction do to the slope and y intercept (would the y intercept be more, less, or equal to 0 and the slope more, less, or equal to 1)

Homework Equations



KE0+PE0+W=PE+KE

The Attempt at a Solution


At first I thought that the slope would be less than 1 and the y intercept below 0, since my experimental results seemed to confirm this and since friction would be "taking" energy away. However, one of my classmates told me there should be no change. Can anyone explain this problem to me?
 
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  • #2
It depends on how you define your work. If your work includes the work done by friction, then there would be essentially no change. If your work only includes work done by the original force, there should be a change.
 
  • #3
Just so I can understand this--is this because friction would be taking away from both sides of the equation? Why "essentially" no change?
 
  • #4
You have work done by both forces. Usually, we define the work done by your force to be positive. In that case, the work done by friction is negative (and is equal to the loss in KE and PE).

So, if you include friction, the graph wouldn't change. The PE+KE of the particle would go down because friction is converting that energy into heat, BUT, the negative work of friction would also bring your W down by the exact same amount. If you don't include friction, the graph will change. The work done by your force is the same, but the PE+KE of the particle will go down due to friction.
 

FAQ: Slope of an Energy with Friction Graph?

What is the slope of an energy with friction graph?

The slope of an energy with friction graph represents the rate of change of energy over a given distance or time. It can also be interpreted as the amount of work done per unit distance or time.

How is the slope of an energy with friction graph calculated?

The slope of an energy with friction graph is calculated by dividing the change in energy by the corresponding change in distance or time. This is represented by the formula: slope = (change in energy) / (change in distance or time).

What does a positive slope on an energy with friction graph indicate?

A positive slope on an energy with friction graph indicates that the energy is increasing over the given distance or time. This could mean that work is being done on the system or that the system is gaining energy from an external source.

What does a negative slope on an energy with friction graph indicate?

A negative slope on an energy with friction graph indicates that the energy is decreasing over the given distance or time. This could mean that work is being done by the system or that the system is losing energy to the surroundings.

Can the slope of an energy with friction graph be used to calculate the force of friction?

Yes, the slope of an energy with friction graph can be used to calculate the force of friction. This can be done by using the formula: force of friction = coefficient of friction * normal force. The coefficient of friction can be determined by taking the absolute value of the slope of the energy with friction graph.

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