51 - Mechanics Part 2 Questions Answers

A large number of identical point masses m are placed along x-axis, at x= 0,1,2,4.........The magnitude of gravitational force on mass at origin (x=0), will be

Asked By: SWATI KAPOOR
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Joshi sir comment

The magnitude of gravitational force on mass at origin (x=0), will be

Gmm/12 + Gmm/22 + Gmm/42 + Gmm/8+ .........................

= [Gmm/12][1+(1/4)+(1/16)+....................]

= Gmm[1/(1-(1/4)]

solve?

Physics >> Mechanics Part 2 >> Gravitation Medical Exam

A satellite of mass 200 kg revolves around a planet of mass 5 x 1030kg in a circular orbit of radius 6.6 x 106 m. Binding energy of the satellite.

Asked By: SWATI KAPOOR
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Joshi sir comment

Binding energy = GMm/2R

can the linear speed of two objects be different if they have the same angular speed?

Asked By: VIBHU GOEL
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Joshi sir comment

angular speed depends on the distance from pivot also so v may be same or different 

formula affilated is v = r ω

Physics >> Mechanics Part 2 >> Gravitation Medical Exam

NAME  THE OUTERMOST LAYER OF SUN ????

Asked By: SARIKA SHARMA
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Joshi sir comment

i think its corona

Physics >> Mechanics Part 2 >> Gravitation Medical Exam

A STONE WEIGHS 9N AT A PLACE ON THE SURFACE OF EARTH HAVING LATITUDE π/2 . ITS MASS AT CENTRE OF EARTH WILL BE (kg)

 

1) 10/ 37√2

2 ) 10√2

3) 5

4) 15

Asked By: SARIKA SHARMA
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Joshi sir comment

π/2 means it is pole so mg = 9 implies that m = 9/9.8

same will be the mass at centre of earth

THE  TERMINAL SPEED ATTAINED BY AN Al  SPERE OF RADIUS 1mm  FALLING THROUGH H2O AT 200C WILL BE CLOSE TO ??

ANS 4.6 m/s

(assume laminar flow , specific gravity of Al=2.7 & η H2O =8X 10-4 PL.)

Asked By: SARIKA SHARMA
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Joshi sir comment

v = 2r2g(D-d)/9η

so v = 2(.001)2*9.8(2700-1000)/9*8*10-5

solve it 

WHEN TWO SUBSTANCES OF DENSITYρ1 & ρ2 MIXED IN EQUAL VOLUME THEN RELATIVE  DENSITY OF MIXTURE IS 4    , WHEN THEY R MIXED IN EQUAL MASSES THEN RELATIVE DENSITY =3. THEN ρ1 X ρ 2  =?

ANS 12

Asked By: SARIKA
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Joshi sir comment

in first case 4 = [ρ1V + ρ2V]/2V

and 3 = [m+m]/ [m/ρ1 + m/ρ2]

solve now

A BALL FLOATS ON D SURFACE OF H2O IN A CONTAINER EXPOSED TO ATMOSPHERE . IF D CONTAINER IS COVERED & AIR IS COMPRESSED , D BALL WILL RISE . WHY?

Asked By: SARIKA
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Joshi sir comment

beacause due to compression density of air will increase and upthrust by air will make some contribution in the net upthrust so some extra part of the body will come outside water.

Physics >> Mechanics Part 2 >> Gravitation Medical Exam

a double star consist of 2 stars of mass m & .2m. distance b/w them is r. d 2 stars revolve under their mutual gravitatn force then d 2 stars have equal periods of revolution . HOW?

Asked By: SARIKA SHARMA
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Joshi sir comment

according to newtons third law both star will give equal force to each other

so for first star of mass m,           m(2r/3)ω2  = F or ω = [3F/2mr]1/2

similarly for second                   2m(r/3)ω2 = F   or  ω = [3F/2mr]1/2

here 2r/3 and r/3 are taken according to centre of mass criteria.

my previous ques from fluid topic is not solved yet so pls reply that ques & that of chem of some other one 

Asked By: SARIKA SHARMA
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Joshi sir comment

very soon you will get the answers

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