Question

a book of weight 20N is pressed between two hands and each hand exerts a force of 40N. if book just start to slide down. then the coefficient of friction is

Answer 1

When book just starts sliding
friction = mg
μN = mg

μ = mg / N
= (20) / (2 × 40) ………[∵ normal reaction is by two hands]
= 0.25

Coefficient of friction is 0.25

Answer 2

0.25 is the answer of coefficient of friction that we get here.

Explanation:

The coefficient of friction for a certain situation like the one given in the question where the friction between hands and Book has to be found out.

It can be done using a formula  that says mg = uN,

where both the sides have Newton as the units of force.

Left hand side is mass into gravity which is again in the form of Newton is given as 20 Newton in the question while the Newton on the right side is actually the sum of the forces applied by both the hands which is 40 each  not putting this in form of solution,

We get

20 = u(40+40)

$\frac{20}{80}$ = u

u = 0.25

Therefore, the coefficient of friction is u = 0.25 .

To know more:

Define coefficient of friction?

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