Question

Q IF A BODY IS PROJECTED UPWARD WITH SPEED 1/2 OF ESCAPE SPEED OF EARTH THEN MAXn HEIGHT ATTAINED BY IT IS=? 

ANS=R/3  WHERE R=RADIUS OF EARTH

Joshi sir comment

escape velocity = √(2GM/R)   so 1/2 of escape = 1/2√(2GM/R)

so according to given condition on applying energy conservation we will get 

energy at start = energy at the heighest point

or    -GMm/R +  mv2/2 =  -GMm/R1 +  0

or     - GMm/R   +  2GMm/8R =  -GMm/R1 + 0

solve now for finding R1  then find R1-R

Read 1 Solution.

use energy conservation 

-GMm/R +2GMm/8R = 0+ -GMm/R1 where R1 is the distance from the centre of the earth.

solving it u wll get R1 = 4R/3 so h= 4R/3-R =R/3 Ans.

Best SolutionNIKHIL VARSHNEY 12 year ago is this solution helpfull: 1 0

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