Question

A heavy box of mass 20KG is placed on a horizontal surface.Find the normal Reaction (acceleration due to gravity 10m/s²)​

Answer 1

Answer:

Given that,

Mass of block, M=20kg  

Weight (vertically downward), W=20×10=200N

Normal reaction (vertically upward), W=200N

Now, static friction

fs=μmg

fs=0.4×200

fs=80N

So the block will move and kinetic friction would act.

Now, kinetic friction

fk=μmg

fk=0.3×200

fk=60N

As motion start then only kinetic frction will act.

Hence, the frictional force is 60N

Explanation:

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