Sunday

April 20, 2014

April 20, 2014

Posted by **JC** on Thursday, November 6, 2008 at 6:26am.

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.

- Physics -
**drwls**, Thursday, November 6, 2008 at 7:50amCheck your decimal poing on (c). You went from 14,000 net force to 140,000

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

**Related Questions**

Physics - sorry to keep posting this, but I have an assignment based on these ...

Physics (Checking answe) - Sorry for re-posting but I need to know if I did it ...

english - does being shy effects my career path, communication, and... what to ...

Chemistry - Hi; I'm just wondering, I need to write the dissocation equation for...

physics, please help check - A rocket car is traveling on a linear horizontal ...

Cultural Diversity - Consider racial imbalances in education, the economy, ...

General - Please understand that I am not upset with anyone or whatever I just ...

Physics - sorry to repost (again) but I'm not understanding how to solve this: A...

Physics - sorry to repost (again) but I'm not understanding how to solve this: A...

ART please help me i just need to be sure about'em - this type of ad implies the...