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A block of mass 1kg is at rest on a roug...

A block of mass 1kg is at rest on a rough horizontal surface having coefficient of static friction 0.2 and kinetic friciton 0.15, find the frictional forces if a horizontal force,
(a) `F=1N` (b) F=1.96N (c) F=2.5N is applied on a block

Text Solution

Verified by Experts

For this system `a_(1)T=a_(2)(4T+2T+t)impliesa_(1)=7a_(2)`
(a) for `F_(ext)=1.96N,F_(ext)ltf_(max)`
So, body is rest means static friction is present and hence `f_(s)=F_(ext)=1N`
(b) for `F_(ext)=1.96N,F_(ext)=f_(max)=1.96Nsof=1.96N`
(c ) for `F_(ext)=2.5N," "so" "F_(ext)gtf_(max.)`
now body is in moving condition
`thereforef_(max)=f_(k)=mu_(k)N=mu_(k)mg=0.15xx1xx9.8=1.47N`
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