Question

A book of weight 20N is pressed
two hands and each hand exerts
a force of 40N. If the book just starts to slide
Coefficient of friction is
(1) 0.25 2) 0.2
3) 0.5 4)0.1
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Answer 1

Solution

Reaction force on the book due to the pressure exerted due to pressing by two hands is

=R=40N

now ....

the book is just starting sliding...so the reaction force will act along the vertical direction...along two touching surfaces of the book..

and it is=2u(s)R

where ..u(s)=coefficient of sliding friction....

now..

2u(s)R=20

u(s)R=10

=>u(s)=10/R

=>u(s)=(10/40)

=>u(s)=0.25

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Answer 2

Explanation:

right ans is 0.1 when applide force in this condition is 40N and maximum force of friction will 2N

soo it starts at such high force of friction