Max Height: Solving Displacement Problems

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Homework Help Overview

The problem involves calculating the maximum height of a rocket that accelerates from rest for a specified time before decelerating due to gravity. The subject area pertains to kinematics and motion under constant acceleration.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to apply the uniform motion equations for constant acceleration but expresses uncertainty about the setup. Some participants suggest calculating the rocket's velocity after the acceleration phase to find additional displacement during deceleration.

Discussion Status

Participants are exploring different aspects of the problem, including the initial velocity after the acceleration phase and how to incorporate gravitational effects. There is a focus on clarifying the two phases of motion and the corresponding displacements, though no consensus has been reached.

Contextual Notes

There is a mention of the need to consider both the displacement during acceleration and the additional displacement while decelerating under gravity. The original poster has not provided the velocity after the acceleration phase, which is crucial for further calculations.

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Homework Statement


A rocket starts from rest and accelerates for 3.50 s with an acceleration of 5.00 m/s². If it continues to rise until its velocity is zero, what will be its maximum height?


Homework Equations


I thought I had to use the "UNIFORM MOTION with CONSTANT ACCELERATION" formula, which is d=vi*t+(1/2)*a*t²
d = distance
vi = initial velocity
t = time
a = acceleration


The Attempt at a Solution


d = 0*3.5+(1/2)(5.00 m/s²)(3.5)²

I am not sure whether I set up the problem correctly or not.
 
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hey cyspope,
what's the velocity of the rocket after 3.50 s? use this velocity* to determine the extra displacement, [this will be the initial velocity vo], you may use the velocity & displacement equation.



* note the rocket will be decelerating under the effect of g = 9.8 m/s2 till the velocity reaches zero.
 
drizzle said:
hey cyspope,
what's the velocity of the rocket after 3.50 s? use this velocity* to determine the extra displacement, [this will be the initial velocity vo], you may use the velocity & displacement equation.



* note the rocket will be decelerating under the effect of g = 9.8 m/s2 till the velocity reaches zero.

It doesn't says about the velocity of the rocket after 3.50 s. and How would you apply the gravity, which is 9.8 m/s² into the equation?
 
hint:

cyspope said:
A rocket starts from rest and accelerates for 3.50 s with an acceleration of 5.00 m/s²...
 
don't forget, there're two different displacements, d1 [which you can calculate using the first part of the question], and d2 [as described above]. the maximum displacement [height] is then d1+d2
 
Is the answer 63.125 m?
 

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