Lifting a prism; coefficient of friction

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SUMMARY

The discussion revolves around calculating the minimum force required to lift a prism with a mass of 80 g, given a coefficient of friction (μ) of 0.4 between the prism's surface and human skin. The relevant equation is F = μR, where F represents the frictional force and R is the normal force applied. The solution requires understanding the forces acting on the prism, specifically the net force that must equal the weight of the prism, which is influenced by the angle of the prism and the applied forces from two fingers.

PREREQUISITES
  • Understanding of static friction and its formula (F = μR)
  • Basic knowledge of forces and equilibrium in physics
  • Familiarity with the concept of weight and mass
  • Ability to analyze forces acting on an object in two dimensions
NEXT STEPS
  • Study the concept of static friction in detail, focusing on its applications in lifting objects
  • Learn about the principles of force resolution in two-dimensional systems
  • Explore different types of prisms and their geometric properties
  • Investigate the relationship between normal force and applied force in various scenarios
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in understanding the principles of friction and force application in lifting objects. It is particularly relevant for those studying mechanics and static equilibrium.

kate12
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Homework Statement


A prism has a mass of m = 80 g, and you wish to lift it, touching
the upper two faces only. If the coecient of friction between the prism’s surface and
your skin is  = 0:4, what is the minimum force that must be applied to each face?


Homework Equations


F=μR


The Attempt at a Solution


I drew the forces perpendicular to the two surfaces. I don't really know how to resolve them, and how F=μR comes into it.
 
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The question seems incomplete without mentioning what kind of prism it is...You cannot resolve the forces to anything useful. if you don't know the prism angle.
 
We need a net force equal the weight of the prism, passing thru the centre of mass.
This net force is equal to the resultant of 2 forces, each from each finger.
The force from each finger is equal or less than maximum static friction between finder and prism.
The static friction is equal μN where N equal to force applied if it is applied perpendicularly to the plane of the prism.
 

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