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Standard XII

Physics

Work by Multiple Forces

A window scru...

Question

A window scrubber is used to brush up a vertical window as shown in figure. The brush weigh $12 N$ and coefficient of kinetic friction of $0.15$ . Calculate $F$ :

15 N

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10.2 N

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17.2 N

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18.1 N

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Solution

The correct option is C $17.2 N$
Here weight of the brush $= m g = 12 N$
Friction force $= f = μ N = μ F cos 53$
from FBD, $F sin 53 = μ F cos 53 + m g$
Now $m g = 12, F (s i n 53 - μ c o s 53) = m g$
On solving we will get
$∴ F = 17.2 N$

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A window scrubber is used to brush up a vertical window as shown in figure. The brush weigh 12N and coefficient of kinetic friction of 0.15. Calculate F :

The correct option is C 17.2NHere weight of the brush =mg=12NFriction force =f=μN=μFcos53from FBD, Fsin53=μFcos53+mgNow mg=12,F(sin53−μcos53)=mgOn solving we will get ∴F=17.2N

A window scrubber is used to brush up a vertical window as shown in figure. The brush weigh $12 N$ and coefficient of kinetic friction of $0.15$ . Calculate $F$ :

The correct option is C $17.2 N$
Here weight of the brush $= m g = 12 N$
Friction force $= f = μ N = μ F cos 53$
from FBD, $F sin 53 = μ F cos 53 + m g$
Now $m g = 12, F (s i n 53 - μ c o s 53) = m g$
On solving we will get
$∴ F = 17.2 N$