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