Work on an incline with friction.

In summary, the problem involves Daphne pushing a 22.0 kg crate up a 30.0 degree incline at a constant velocity for a distance of 10.0 m. In part 1, where the incline is frictionless, Daphne does 1.08E3 J of work. In part 2, where there is a coefficient of kinetic friction of 0.200, Daphne does 1451.4 J of work. To calculate the work done in part 2, the force of kinetic friction must be considered, which is equal to the coefficient of kinetic friction multiplied by the normal force on the body. The direction of the force of friction is against the direction of movement
  • #1
d.tran103
39
0
Okay, I am stuck on this problem that comes in two parts. Please help! Thanks!

Homework Statement



Part 1) Daphne pushes a 22.0 kg crate up a frictionless 30.0 degree incline a distance along the incline of 10.0 m at constant velocity. How much work did Daphne do?

Part 2) Daphne now pushes a 22.0 kg crate up the 30.0 degree incline with a coefficient of kinetic friction of 0.200. As before, she pushes the crate a distance up the incline of 10.0 m at constant velocity. How much work did Daphne do?

Homework Equations


W=Fdcos(theta)

The Attempt at a Solution


Part 1) I'm 100% confident in the answer I got for part 1, w=(9.8 m/ss)(22 kg)(10.0 m)(cos60), w=1.08E3 J.
Part 2) This is where I'm stuck. How does friction apply to this? It changes the force but it isn't working for me. I know the answer is 1451.4J but can't figure out how to get it. Thanks!
 
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  • #2
Force of kinetic friction of the moving body = coefficient of kinetic friction * normal force from the surface on the body.
Direction of the force of friction is against the direction of movement.
 
  • #3
So is 431.2 N my diagonal component and 215.6 my vertical component, making 215.6 the normal force? Thanks!
 

1. How does friction affect work on an incline?

Friction acts as a resistance force that opposes motion, making it more difficult to perform work on an incline. This means more force is required to move an object up an incline with friction compared to a frictionless incline.

2. How is the amount of friction on an incline determined?

The amount of friction on an incline is determined by the coefficient of friction, which is a measure of how rough or smooth the surfaces in contact are. The higher the coefficient of friction, the greater the frictional force.

3. Does the angle of incline affect the amount of friction?

Yes, the angle of incline does affect the amount of friction. As the angle of incline increases, the component of the weight of the object that acts parallel to the incline also increases, resulting in a greater force of friction.

4. How does the weight of an object impact the amount of work required on an incline with friction?

The weight of an object directly affects the amount of work required on an incline with friction. The greater the weight, the more force is needed to overcome the frictional force and move the object up the incline.

5. Can the work done on an incline with friction ever be less than the work done on a frictionless incline?

Yes, it is possible for the work done on an incline with friction to be less than the work done on a frictionless incline. This can occur if the coefficient of friction is low enough that the frictional force is overcome by the component of the weight of the object acting parallel to the incline.

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