A rocket with initial mass of 7.50×103 kg is fired in the vertical direction. Its exhaust gases are ejected at the rate of 4.50×101 kg/s with a relative velocity of 2.200×103 m/s. What is the initial acceleration of the rocket?

Question

What is the acceleration after 20 s have elapsed?

Answer 1

F=ma

mass*velocity= impulse
in the first instance
massrate*velocitygas= force
45.0kg/s*2200m/s=ForceinNEwtons

in twenty seconds, the mass of the rocket is reduced to 7.50E3-45.0*20

a= force/mass= force above/newmass