How Do You Calculate the Coefficient of Kinetic Friction for a Moving Crate?

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SUMMARY

The coefficient of kinetic friction (μk) for a moving crate can be calculated using the equation μk = Fk / (mg), where Fk is the friction force and mg is the weight of the crate. In this case, a horizontal force of 210 N is applied to push a 20 kg crate, resulting in a calculated μk of 1.07. This value indicates that the surface may be exceptionally rough or rubbery, as coefficients of friction greater than 1 are possible under certain conditions. The calculations confirm that the applied force equals the friction force when the crate moves at a constant velocity.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with the concept of friction and its coefficients
  • Basic algebra for solving equations
  • Knowledge of gravitational force calculations (mg)
NEXT STEPS
  • Study the principles of friction in physics, focusing on kinetic friction
  • Learn about different surface materials and their impact on friction coefficients
  • Explore real-world applications of friction calculations in engineering
  • Investigate scenarios where μk exceeds 1 and the implications of such values
USEFUL FOR

Students studying physics, particularly those focusing on mechanics, as well as engineers and professionals involved in material science and surface interactions.

Mebmt
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Homework Statement


Horizontal force of 210 N used to push 20 kg crate over 4 m with constant velocity. Looking for coefficient of kinetic friction.

Homework Equations


a=0
Work done by friction force is:
Net force=ma
Fapp-Fk=ma
210-Fk=0
Friction force = 210

The Attempt at a Solution



friction force=(muk)mg
210=(muk)(20)(9.8)
muk=1.07

Where did I go wrong?
Scott
 
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Mebmt said:

Homework Statement


Horizontal force of 210 N used to push 20 kg crate over 4 m with constant velocity. Looking for coefficient of kinetic friction.


Homework Equations


a=0
Work done by friction force is:
Net force=ma
Fapp-Fk=ma
210-Fk=0
Friction force = 210

The Attempt at a Solution



friction force=(muk)mg
210=(muk)(20)(9.8)
muk=1.07

Where did I go wrong?
Scott
assuming a horizontal surface, looks OK. muk can be greater than 1 for certain rough or rubbery surfaces.
 

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