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4-2.Friction
medium
A block of mass $10 kg$ is moving on a rough surface as shown in figure. The frictional force acting on block is ...... $N$
A$60$
B$20$
C$40$
D$80$
Solution
(b)
If body is moving on rough surface
Frictional force $=\left( f _{ s }\right)_{\max }= f _{ k }$
$=\mu mg$
$=0.6 \times 10 \times 10$
$=60\,N$
Since friction is self adjusting force maximum forc eof $60\,N$ is acting, but here only External force $=20\,N$ is acting so friction can acts is $20\,N$
If external force increases then $f$ will increase and go upto $60\,N$ beyond which object will move
If body is moving on rough surface
Frictional force $=\left( f _{ s }\right)_{\max }= f _{ k }$
$=\mu mg$
$=0.6 \times 10 \times 10$
$=60\,N$
Since friction is self adjusting force maximum forc eof $60\,N$ is acting, but here only External force $=20\,N$ is acting so friction can acts is $20\,N$
If external force increases then $f$ will increase and go upto $60\,N$ beyond which object will move
Standard 11
Physics
