Question

43. A rocket of mass 1000 kg is to be projected vertically
upwards The gases are
exhausted vertically
downwards with velocity 100 m/s with respect
the rocket What is the minimum rate of burning fuel
so as to just lift the rocket upwards against gravitational attractions​

Answer 1

50 kgs−1kgs−1

correct answerB 

100 kgs−1kgs−1

C 

200 kgs−1kgs−1

D 

400 kgs−1kgs−1

Solution:

The velocity of exhaust gases with respect to rocket 

            =100ms−1             =100ms−1 

The minimum force on the rocket to lift it 

   Fmin=mg=l000×10=10000N    Fmin=mg=l000×10=10000N

Hence, minimum rate of burning of fuel is given by 

     dmdt=fminv=10000100      dmdt=fminv=10000100 

     100kgs−1

Answer 2

Answer

Explanation:

at least 1000km/second