NEET Physics Laws of Motion Questions Solved


For a rocket moving in free space, the fraction of mass to be disposed off to attain a speed equal to two times the exhaust speed is given by (given e -7.4) (a) 0.63 (b) 0.37 (c) 0.50 (d) 0.86

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(2)

 

                            

If acceleration of wedge is 'a'From wedge frame:

                           

Block is in equilibrium   ma cos θ=mg sin θ        a=g tan θ        a=g34           tan 37°=34   For whole system,          Mg=M+4+1a     asys=Net driving forceMass of system          Mg=M+53g4              4M=3M+15               M=15 kg

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Tmax=mv12R+mg = mv12+mgRRTmin=mv22R-mg = mv22-mgRRAs,    TmaxTmin = 4=v12+gRv22-gR             4v22-gR = v12+gR                     v12 = 4v22-5gR                ............iConserving enerfy from L to H -          12mv12 = 12mv22 + 2mgR               v12 = v22 + 4gR                        ...........iiOn comparing both equations-            4v22-5gR = v22 + 4gR            3v22 = 9gR               v22 = 3×10×103            v2=10 m/s

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(3)

                               

length of the element = R×2θmass of full length = mmass of unit length = m2πRmass of the element = m2πR×R×2θ                              dm =m2π×θ

2TSinθ=dmv2R= mπ×Q×v2RAs, θ is very small, Sinθθ 2=mπ×Q×v2R       T=mv22πR

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