Question

a rocket has initial mass 240kg rejected fuel at the rate of 6kg/s with a velocity 2km/s vertically downward relative to itself. calculate it's velocity 25sec and start, taking initial velocity to be 0 and neglect gravity​

Answer 1

Answer:

☆Main formula :-

F = $\frac {d (mv)}{dt}$

F= ma

v=u+at

#solution:

•F = $\frac {dm}{dt}$×v (variable mass system)

•F = 6kg/s × 2000m/s

•F = 12000N

•F = ma

•12000 = 240 × a

• a = 50m/s^2

•v=u+at

•v = 0 + 50×25

•v = 1250 m/s☆☆

☆Theory:

• as the mass is variable with respect to time and rocket is moving with constant velocity...these gases when hit the ground...in reaction its create the thurst force
• if gravity is taken then thurst force have to be more then that above for upward motion

hope it helps!