Sorry for posting so many, but I just need to make sure I'm on the right track.
Just need someone to check my working and answers.
A rocket has a mass 3000kg. The fuel used in the rocket has an additonal mass of 500kg. At the launch, the rocket accelerates at 4m/s/s. Using 10m/s/s as gravity.
a) Calculate the net force on the rocket.
f=ma (Newton's 2nd Law)
=3500 x 4
=14000 N
b) What is the weight of the rocket at launch?
w=mg
=3500 x 10
=35000N
c) Determine the upward force exerted by the rocket motors at the instant of the launch
F(net)=W + F(up)
=35000 + (4 x 35000)
=175000N (upwards)
d) The rocket takes 3 minutes to burn all of it's fuel. If the rocket motors suply a constant force, would you expect the acceleration to remain constant during the first 3 minutes. Explain your answer.
No. If the rocket takes 3 mintues to burn all of it's fuel, during that time, the mass of the fuel decreases. Since the force remains the same thorughout the 3 mintues, the rocket will accelerate when there is less mass.
Determine
e) the upward force acting on the rocket after the fuel tank beocme empty.
F(up)=0N
f)the acceleration of the rocket after this instant.
10m/s/s due to gravity.
1 answer
d) The acceleration rate increases as the mass (including fuel) decreases
e) is correct. So is (f). Upward thrust ends when the fuel is gone