Relationship between work and kinetic energy

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SUMMARY

The discussion centers on the relationship between work and kinetic energy in a scenario involving a block of ice sliding down a frictionless ramp at an angle of 50°. A force of 50 N is applied up the ramp, resulting in an increase in kinetic energy of 80 J. However, the actual increase in kinetic energy, when accounting for the work done against the applied force, is determined to be 25 J. The key takeaway is that the work done by the applied force directly influences the change in kinetic energy, illustrating the principle that work equals the change in kinetic energy.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with the work-energy theorem
  • Basic knowledge of forces and frictionless surfaces
  • Ability to manipulate equations involving work (W = Fd) and kinetic energy (delta K = Kf - Ki)
NEXT STEPS
  • Study the work-energy theorem in detail
  • Learn about frictionless surfaces and their implications in physics problems
  • Explore the concept of net forces and how they affect motion
  • Practice problems involving forces and kinetic energy changes
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in understanding the principles of work and kinetic energy in mechanics.

lemonpie
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Homework Statement


A block of ice slides down a frictionless ramp at angle q = 50° while an ice worker pulls on the block (via a rope) with a force that has a magnitude of 50 N and is directed up the ramp. As the block slides through distance d = 0.50 m along the ramp, its kinetic energy increases by 80 J. How much greater would its kinetic energy have been if the rope had not been attached to the block?
http://www.lowellphysics.org/beta/Textbook%20Resources/Chapter%207.%20Kinetic%20Energy%20and%20Work/Problems/c07x7_11.xform_files/nw0315-n.gif

Homework Equations


W = Fd, delta K = Kf - Ki

The Attempt at a Solution


I found W = Fd = (50)(0.5) = 25 J. Then I tried to figure out the kinetic energy at the top and bottom of the ramp, but I got stuck because the mass of the block wasn't given. Then I checked the back of the book and found that the answer to the increase in kinetic energy was actually 25 J, and in some vague way this makes sense to me, but not totally, and not in a way I would have been able to figure out on my own. Can someone give me some helpful words to explain this?
 
Physics news on Phys.org
Work done = change in KE.
From this find the net down ward force (F-Fr).
 
rl.bhat said:
Work done = change in KE.

thanks. i feel stupid.
 

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