Rocket Launch Kinematics motion

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Homework Help Overview

The problem involves kinematics related to a rocket launch decision, specifically assessing whether the rocket can ascend through a band of clouds within a specified time limit while considering its acceleration.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to calculate the rocket's final velocity and the distance it can travel within 30 seconds to determine if the launch should proceed. Some participants affirm the calculations, while others question how the equations would change if both the rocket's acceleration and gravity were considered.

Discussion Status

The discussion includes affirmations of the original poster's calculations, alongside inquiries about the effects of gravity on the rocket's acceleration. Participants are exploring different interpretations of the problem without reaching a consensus.

Contextual Notes

The problem is constrained by the requirement that the rocket must not be out of sight for more than 30 seconds and must ascend through a specific altitude range defined by the cloud thickness.

negation
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Homework Statement



You're at a mission control for a rocket launch, deiciding whether to let the launch proceed. A band of clouds 5.3km thick extends upwards from 1.9km altitude. The rocket will accelerate at 4.6ms^-2 and it isn't allowed to be out of sight for more than 30s.
Should the launch be allowed?

Homework Equations



None.

The Attempt at a Solution



Clear skies ranges from y = [0m,1900m]
Thick cloud ranges from y = [1900m,7200m]

vf^2 - vi^2 = 2a(yf - yi)
vf^2 = 2(4.6ms^-2)(1900_
vf = 132.2ms^-1

At the instantaneous moment rocket is at position y = 1900m, vf = 132.2ms^-1

From y = 1900m, vf = 132.2ms^-1 = vi

yf - yi = vit + 0.5at^2
yf - yi = 132.2ms^-1 (30s) + 0.5(4.6ms^-2)(30)^2
yf - yi = 6036m

[yf - yi] = 6036m > 5300m from t = [0s,30s]

Launch should be allowed.
 
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Looks right.
 
haruspex said:
Looks right.

How would the equation change if the acceleration of the rocket and gravity were included within the parameter? I'm curious.
 
negation said:
How would the equation change if the acceleration of the rocket and gravity were included within the parameter? I'm curious.

It already is. The net acceleration after taking into account the opposing deceleration from gravity is 4.6m/s^2. Without gravity, the rocket could presumably accelerate at (4.6 + 9.8) = 14.4 m/s^2. The rocket thrust force is 14.4*M, where M is the mass of the rocket.
 
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