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The-surface-between-wedge-and-block-is-rough-Coefficient-of-friction-Find-out-the-range-of-F-such-that-there-is-no-relative-motion-between-wedge-and-block-The-wedge-can-move-freely-on-smooth-gr




Question Number 20581 by Tinkutara last updated on 28/Aug/17
The surface between wedge and block  is rough (Coefficient of friction μ).  Find out the range of F such that,  there is no relative motion between  wedge and block. The wedge can move  freely on smooth ground.
Thesurfacebetweenwedgeandblockisrough(Coefficientoffrictionμ).FindouttherangeofFsuchthat,thereisnorelativemotionbetweenwedgeandblock.Thewedgecanmovefreelyonsmoothground.
Commented by Tinkutara last updated on 28/Aug/17
Commented by ajfour last updated on 28/Aug/17
Commented by ajfour last updated on 28/Aug/17
Diagram above shows the case  when F    is minimum and there  is no relative motiin b/w block  and wedge.  I shall use pseudo force directed  towards left to be able to analyse  equilibrium of block from frame  of wedge.  ΣF_x =0    ⇒−μNcos θ−ma+Nsin θ=0  ...(i)  ΣF_y =0  ⇒ μNsin θ+Ncos θ=mg   ...(ii)  ⇒  N=((mg)/(cos θ+μsin θ))  using this in (i):   ma=((mg(sin θ−μcos θ))/(cos θ+μsin θ))  As  F=(M+m)a  , so  F_(minimum) =(((M+m)g(tan θ−μ))/(1+μtan θ))  for F_(maximum) , μ→−μ  F_(maximum) =(((M+m)g(tan θ+μ))/((1−μtan θ))) .
DiagramaboveshowsthecasewhenFisminimumandthereisnorelativemotiinb/wblockandwedge.Ishallusepseudoforcedirectedtowardslefttobeabletoanalyseequilibriumofblockfromframeofwedge.ΣFx=0μNcosθma+Nsinθ=0(i)ΣFy=0μNsinθ+Ncosθ=mg(ii)N=mgcosθ+μsinθusingthisin(i):ma=mg(sinθμcosθ)cosθ+μsinθAsF=(M+m)a,soFminimum=(M+m)g(tanθμ)1+μtanθforFmaximum,μμFmaximum=(M+m)g(tanθ+μ)(1μtanθ).
Commented by Tinkutara last updated on 28/Aug/17
Thank you very much Sir! But can it be  solved without using pseudo force?
ThankyouverymuchSir!Butcanitbesolvedwithoutusingpseudoforce?
Commented by ajfour last updated on 28/Aug/17
check again, diagram shows  situation when force is minimum.  I corrected my answers.  without pseudo force,  ΣF_y =0, still the same  but ΣF_x =ma  ⇒ Nsin θ−μNcos θ=ma  thats just the difference..
checkagain,diagramshowssituationwhenforceisminimum.Icorrectedmyanswers.withoutpseudoforce,ΣFy=0,stillthesamebutΣFx=maNsinθμNcosθ=mathatsjustthedifference..

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