Question

A dock worker loading crates on a ship finds that a 20 kg crate, initially at rest on a horizontal surface, requires a 89 N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 47 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.

Answer 1

Answer:0.45

Step-by-step explanation:

Given

Mass of crate
`m=20 kg`

Force
`F=89 N`

After crate start moving a force of 47 N is required to keep it moving with a constant speed

So we can conclude that 89 N is the force which is required to overcome static friction and after that kinetic friction comes into play which is less than static friction

Static friction
`=\mu N`

where
`\mu`is coefficient of static friction

`N=mg`

Static Friction
`=\mu mg=89`

`\mu =(89)/(20* 9.8)`

`\mu =0.45`