Interesting deal with friction and energy

In summary, the block slides down the hill from rest at s=0 to the final position/distance s, but because of the coefficient of friction, it does so in an increasingly rough manner.
  • #1
DaMastaofFisix
63
0
Hey everyone, I have a free response question concerning some rather simple mechanics presented in a ratheruh...interesting way. We have a block of mass M, that slides don a hill at an angle of theita. the block slides down the hill from rest at s=0 to the final position/distance s. Here's the catch. The coefficient of friction is u=as, where a is a constant and s is the distance down the hill. So its obvious that this is an incresingly rough incline.

a) Show all the forces acting on the block, in terms of only what's given (and g)
b) Draw a frictional force versus distance graph
c) Fins the area under the graph to deteminr the work done on the block
d) Find out how far the block slides down the hill

This is a doosey. I understand the setup for all of the steps,but the problem comes in verifying my algebra and making sure I am using the right setup. all answers must be expressed in terms of the quantities given. I got some answers, most importantly that the distance is tan(theita)/a. Will someone help me OUT?!
 
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  • #2
If y'all need to see some more work, let me know, I'll upload everything I have.
 
  • #3
For b) just find the normal force and write a linear equation with the friction, distance, and normal (f(s)=N*a*s)
c) simple geometry
d) check when the friction is greater than the componant of gravity that's pulling the block down the hill.
 
  • #4
DaMastaofFisix said:
I got some answers, most importantly that the distance is tan(theita)/a.
It looks like you solved for the point where the friction force equals the component of gravity down the slope; instead, find the point where the change in gravitational PE equals the work done by the friction force.
 
  • #5
Thanks guys, helped a whole bunch. I new I was on the right track, but I got stuck at the crossroads. Thanks a bunch. Next post coming up will be thw work that I've done.
 

1. What is friction?

Friction is the force that resists the relative motion of two surfaces in contact. It is caused by the microscopic irregularities in the surfaces and the interlocking of the rough edges.

2. How does friction affect energy?

Friction converts kinetic energy, or the energy of motion, into thermal energy, or heat. This means that energy is lost due to friction and cannot be used for other purposes.

3. Can friction be useful?

Yes, friction can be useful in many ways. It helps us walk, grip objects, and stop moving vehicles. It also allows machines to function properly by providing necessary resistance.

4. How can we reduce friction?

Friction can be reduced by using lubricants, such as oil or grease, between two surfaces. Smoother surfaces and reducing the force between two objects can also help decrease friction.

5. Can friction be completely eliminated?

No, it is not possible to completely eliminate friction. However, it can be minimized by using materials with low coefficients of friction and employing techniques to reduce friction, such as lubrication.

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