1.

A 500kg rocket is set for verticle firing. The exhaust speed is `800ms(-2)` . To give an initial upward acceleration of `20ms(-2)` , the amount of gas ejected per second to supply the needed thrust will be `(g=10ms(-2)`A. `127.5kgs^(-1)`B. `187.5kgs^(-1)`C. `185.5kgs^(-1)`D. `137.5kgs^(-1)`

Answer» Correct Answer - B
`F(umd)/(dt)=m(g+a)` .
`implies(dm)/(dt)=(m(g+a))/(u)=(5000xx(10+20))/(800)=187.5kg//s` .


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