What is the rocket's initial upward acceleration?

In summary, the conversation discusses a 20000kg rocket with a rocket motor that generates 3E5 N of thrust. In Part A, the question asks for the rocket's initial upward acceleration, which is determined to be 5.2 m/s^2. In Part B, the rocket's acceleration at an altitude of 5km is 6m/s^2 and the question asks for the mass of fuel burned, which is not known. The equation used in Part A is F_thrust_=ma-mg_earth_. However, this equation does not work for Part B and the correct answer is unknown.
  • #1
cookiekid20
1
0

Homework Statement



A 20000kg rocket has a rocket motor that generates 3E5 N of thrust.
PartA:
What is the rocket's initial upward acceleration? Express your answer using two significant figures.
Part B:
At an altitude of 5km the rocket's acceleration has increased to 6m/s^2. What mass of fuel has it burned? Use wo significant figures in your answer.

Homework Equations


Part A:
I used the equation F_thrust_=ma-mg_earth_
Part B:
I dont' know the equation.


The Attempt at a Solution


PartA: I got the right answer 5.2 m/s^2
Part B: I got it wrong i tried using the same equation as part A but didn't work.
 
Physics news on Phys.org
  • #2
It should have worked. The thrust is constant only m has changed. What did you get?
 
  • #3


I would like to clarify that the equation used in Part A is incorrect. The correct equation for calculating initial upward acceleration is F_net = ma, where F_net represents the net force acting on the rocket, m is the mass of the rocket, and a is the acceleration. In this case, the net force is equal to the thrust generated by the rocket motor minus the force of gravity (mg). Therefore, the correct equation for Part A is 3E5 N - (20000 kg)(9.8 m/s^2) = (20000 kg)a. Solving for a, we get an initial upward acceleration of 5.2 m/s^2, which is the correct answer.

For Part B, we can use the equation F_net = ma again. At an altitude of 5km, the net force acting on the rocket is equal to the thrust generated by the rocket motor minus the force of gravity (mg), minus the force of air resistance (F_air). We can assume that the force of air resistance is negligible at this altitude, so the equation becomes 3E5 N - (m)(9.8 m/s^2) = (m)(6 m/s^2). Solving for m, we get a mass of 8.1 kg of fuel burned.
 

1. What is meant by the rocket's initial upward acceleration?

The rocket's initial upward acceleration refers to the rate at which the rocket's velocity increases in an upward direction at the beginning of its flight.

2. How is the initial upward acceleration of a rocket calculated?

The initial upward acceleration of a rocket can be calculated by dividing the change in its velocity by the change in time during the initial stage of its flight. This can be represented by the formula a = (vf - vi) / t, where a is the acceleration, vf is the final velocity, vi is the initial velocity, and t is the time interval.

3. What factors affect the rocket's initial upward acceleration?

The main factors that affect the rocket's initial upward acceleration are the force of the rocket's engines, the mass of the rocket, and the amount of air resistance or drag acting on the rocket. Other factors such as wind speed and direction can also have an impact.

4. Why is the initial upward acceleration of a rocket important?

The initial upward acceleration of a rocket is important because it determines how quickly the rocket can gain altitude and reach its desired destination. It also affects the amount of fuel and thrust needed for the rocket to achieve its desired velocity and trajectory.

5. Can the rocket's initial upward acceleration change during its flight?

Yes, the rocket's initial upward acceleration can change during its flight due to various factors such as changes in air resistance, thrust, and gravity. For example, as the rocket leaves the Earth's atmosphere, the amount of air resistance decreases, causing the initial upward acceleration to increase.

Similar threads

  • Introductory Physics Homework Help
2
Replies
42
Views
2K
  • Introductory Physics Homework Help
Replies
14
Views
731
  • Introductory Physics Homework Help
Replies
10
Views
604
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
883
  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • Introductory Physics Homework Help
Replies
13
Views
2K
  • Introductory Physics Homework Help
2
Replies
53
Views
3K
  • Introductory Physics Homework Help
Replies
2
Views
756
Back
Top