A dock worker loading crates on a ship finds that a 27 kg crate, initially at rest on a horizontal surface, requires a 80 N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 56 N is required to keep it moving with a constant speed. The acceleration of gravity is 9.8 m/s 2 . Find the coefficient of static friction between crate and floor.

Question

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Respuesta :

nuuk nuuk · Answer 1 · 2019-11-05T05:19:35+01:00

Answer:0.302

Explanation:

Given

mass of crate m=27 kg

Force required to set crate in motion is 80 N

Once the crate is set in motion 56 N is require to move it with constant velocity

i.e. 80 N is the amount of force needed to just overcome static friction and 56 is the kinetic friction force

thus

[tex]f_s(static\ friction)=\mu \cdot N[/tex]

where [tex]\mu [/tex]is the coefficient of static friction and N is Normal reaction

[tex]N=mg[/tex]

[tex]f_s=\mu mg[/tex]

[tex]\mu mg=80[/tex]

[tex]\mu =\frac{80}{27\times 9.8}[/tex]

[tex]\mu =0.302 [/tex]