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Question Number 70831 by ajfour last updated on 08/Oct/19

Commented by ajfour last updated on 08/Oct/19

Stick of mass m, length b is  released as shown. As it slides  down and breaks contact with  hemisphere, the top end is at  angular position β. Assume  no friction, find β.

Stickofmassm,lengthbisreleasedasshown.Asitslidesdownandbreakscontactwithhemisphere,thetopendisatangularpositionβ.Assumenofriction,findβ.

Answered by ajfour last updated on 08/Oct/19

Answered by mr W last updated on 08/Oct/19

Commented by ajfour last updated on 10/Oct/19

so far, so good, how do we  utilise ω in determining β, Sir?  (you like the question, sir?)

sofar,sogood,howdoweutiliseωindeterminingβ,Sir?(youlikethequestion,sir?)

Commented by mr W last updated on 09/Oct/19

OA=R[cos β+(√((b^2 /R^2 )−sin^2  β))]  AC=OA tan β=R[sin β+tan β(√((b^2 /R^2 )−sin^2  β))]  BC=((OA)/(cos β))−R=(R/(cos β))(√((b^2 /R^2 )−sin^2  β))  CD^2 =((AC^2 +BC^2 )/2)−(b^2 /4)  CD^2 =(R^2 /2){(1/(cos^2  β))((b^2 /R^2 )−sin^2  β)+sin^2  β[1+(1/(cos β))(√((b^2 /R^2 )−sin^2  β))]^2 }−(b^2 /4)  I_C =I_0 +mCD^2   I_C =((mb^2 )/(12))+((mR^2 )/2){(1/(cos^2  β))((b^2 /R^2 )−sin^2  β)+sin^2  β[1+(1/(cos β))(√((b^2 /R^2 )−sin^2  β))]^2 }−((mb^2 )/4)  I_C =((mR^2 )/2){(1/(cos^2  β))((b^2 /R^2 )−sin^2  β)+sin^2  β[1+(1/(cos β))(√((b^2 /R^2 )−sin^2  β))]^2 }−((mb^2 )/6)  Δh=(R/2)((b/R) cos α−sin β)  (1/2)I_C ω^2 =mgΔh  ((R/2){(1/(cos^2  β))((b^2 /R^2 )−sin^2  β)+sin^2  β[1+(1/(cos β))(√((b^2 /R^2 )−sin^2  β))]^2 }−(b^2 /(6R^2 )))ω^2 =g((b/R) cos α−sin β)  let λ=(b/R)  ((1/2){(1/(cos^2  β))(λ^2 −sin^2  β)+sin^2  β[1+(1/(cos β))(√(λ^2 −sin^2  β))]^2 }−(λ^2 /6))ω^2 =(g/R)(λ cos α−sin β)  ⇒ω=(√(g/R))(√((6(λ cos α−sin β))/(3{(1/(cos^2  β))(λ^2 −sin^2  β)+sin^2  β[1+(1/(cos β))(√(λ^2 −sin^2  β))]^2 }−λ^2 )))  ....

OA=R[cosβ+b2R2sin2β]AC=OAtanβ=R[sinβ+tanβb2R2sin2β]BC=OAcosβR=Rcosβb2R2sin2βCD2=AC2+BC22b24CD2=R22{1cos2β(b2R2sin2β)+sin2β[1+1cosβb2R2sin2β]2}b24IC=I0+mCD2IC=mb212+mR22{1cos2β(b2R2sin2β)+sin2β[1+1cosβb2R2sin2β]2}mb24IC=mR22{1cos2β(b2R2sin2β)+sin2β[1+1cosβb2R2sin2β]2}mb26Δh=R2(bRcosαsinβ)12ICω2=mgΔh(R2{1cos2β(b2R2sin2β)+sin2β[1+1cosβb2R2sin2β]2}b26R2)ω2=g(bRcosαsinβ)letλ=bR(12{1cos2β(λ2sin2β)+sin2β[1+1cosβλ2sin2β]2}λ26)ω2=gR(λcosαsinβ)ω=gR6(λcosαsinβ)3{1cos2β(λ2sin2β)+sin2β[1+1cosβλ2sin2β]2}λ2....

Commented by mr W last updated on 10/Oct/19

nice question sir! but not easy.

nicequestionsir!butnoteasy.

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