Kinematic Problem: Finding Average and Instantaneous Velocity

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Homework Help Overview

The discussion revolves around a kinematic problem involving an airplane that accelerates at a constant rate. The original poster presents a scenario where the airplane accelerates from an initial velocity of 16 m/s to a final velocity of 28 m/s, with a constant acceleration of 4.0 m/s². The questions posed include finding the average velocity, the duration of acceleration, and the point at which the instantaneous velocity equals the average velocity over the interval.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to calculate the average velocity and total time of acceleration, noting that they found the average velocity to be 22 m/s and the total time to be 3.0 seconds. They express uncertainty about how to determine when the instantaneous velocity equals the average velocity for the interval.
  • Some participants suggest using the equation V = vi + at to explore the relationship between instantaneous and average velocity.
  • One participant provides an analogy involving accelerating from traffic lights to illustrate the concept of instantaneous velocity being equal to average velocity at a specific moment during acceleration.

Discussion Status

The discussion is active, with participants engaging in clarifying the relationship between average and instantaneous velocity. Some guidance has been offered regarding the use of kinematic equations, and the analogy provided helps to contextualize the problem. However, there is no explicit consensus on the exact method to find the time when instantaneous velocity equals average velocity.

Contextual Notes

Participants note that part of the problem serves as a learning exercise, indicating that the exploration of instantaneous versus average velocity is intended to enhance understanding for future problems.

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Homework Statement



An airplane maintains a constant acceleration of 4.0m/s^2 as it speeds up from 16m/s [E] to 28 m/s [E].

A what is the average velocity?

b) how long does the airplane accelerate?

c) when is the instantaneous velocity equal to the average velocity for the interval?

a= 4.0 m/s^2

vi= 16m/s [E]
vf= 28m/s[E]

Homework Equations


The Attempt at a Solution



i found the answer to A and B

Average velocity = 22 m/s. Total time = 3.0 s

I don't know how instantaneous velocity is related to average velocity for the interval. Or how to find the answer. Someone help me?
 
Last edited:
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If you found the average velocity to be 22m/s it is asking when the instantaneous velocity is 22m/s which should just be V = vi + at
 
Ok got it thanks :)
 
hotshot1kille said:

Homework Statement



An airplane maintains a constant acceleration of 4.0m/s^2 as it speeds up from 16m/s [E] to 28 m/s [E].

A what is the average velocity?

b) how long does the airplane accelerate?

c) when is the instantaneous velocity equal to the average velocity for the interval?

a= 4.0 m/s^2

vi= 16m/s [E]
vf= 28m/s[E]


Homework Equations





The Attempt at a Solution



i found the answer to A and B

Average velocity = 22 m/s. Total time = 3.0 s

I don't know how instantaneous velocity is related to average velocity for the interval. Or how to find the answer. Someone help me?

When are the two numerically equal?

Suppose you accelerated away from traffic lights for 10 seconds. After 10 seconds you may have reached quite a high speed, but your average speed will be less than that. At some time during the 10 seconds, the speedo will have shown a speed that just happens to equal your average speed [you won't have realized at the time, since you need the full trip to calculate your average speed]. When was that time?
 
ahh ok thank you so much!
 
hotshot1kille said:

Homework Statement



An airplane maintains a constant acceleration of 4.0m/s^2 as it speeds up from 16m/s [E] to 28 m/s [E].

A what is the average velocity?

b) how long does the airplane accelerate?

c) when is the instantaneous velocity equal to the average velocity for the interval?

a= 4.0 m/s^2

vi= 16m/s [E]
vf= 28m/s[E]


Homework Equations





The Attempt at a Solution



i found the answer to A and B

Average velocity = 22 m/s. Total time = 3.0 s

I don't know how instantaneous velocity is related to average velocity for the interval. Or how to find the answer. Someone help me?

btw; Part C of this problem is a learning exercise, so that in future you will know the bit I highlighted red.
 
ok thank you
 

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