Distance, velocity & Acceleration

  • Context: High School 
  • Thread starter Thread starter otomanb
  • Start date Start date
  • Tags Tags
    Acceleration Velocity
Click For Summary

Discussion Overview

The discussion revolves around the concepts of distance, velocity, and acceleration, particularly in the context of a bird flying a specific distance in a given time. Participants explore how to derive acceleration from average velocity and the implications of using different equations of motion.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that differentiating distance gives velocity, and further differentiation gives acceleration, but question how to determine acceleration from average velocity.
  • One participant suggests that if the average velocity is calculated as distance divided by time, then acceleration is zero, implying constant velocity.
  • Another participant points out that average velocity does not provide information about changes in velocity during the flight, suggesting multiple possible acceleration profiles for the bird.
  • There is a mention that to find acceleration, the actual function of position over time must be known.
  • One participant argues that using the equation of motion \(2as = vf^2 - vi^2\) can yield an acceleration value, but questions arise regarding the assumptions of initial and final velocities.
  • Another participant expresses confusion about using constant acceleration equations when discussing a scenario that may not involve constant acceleration.

Areas of Agreement / Disagreement

Participants express differing views on whether the bird's flight involves constant velocity or varying acceleration, leading to an unresolved discussion regarding the application of equations of motion in this context.

Contextual Notes

Participants highlight the need for specific information about the bird's velocity at different points in time to accurately determine acceleration, indicating that assumptions about constant acceleration may not hold in this scenario.

otomanb
Messages
59
Reaction score
0
taking derivation of distance equation is easy as every body knows.
differentiating distance we get velocity and differentiating velocity we get acceleration
but if a bird fly from one tree to another of distance 50m in 3 sec. we can get it's velocity by
v=s/t but how can we get it's acceleration ?
 
Physics news on Phys.org
hi otomanb! :smile:
otomanb said:
if a bird fly from one tree to another of distance 50m in 3 sec. we can get it's velocity by v=s/t but how can we get it's acceleration ?

if v = s/t, then the acceleration is zero :wink:
 
But how ?
:rolleyes:
 
In calculating that velocity as "distance divided by time", you are calculating the average velocity, a constant. Since the velocity does not change, there is no acceleration.
 
Only when the function x=f(t) is given, can we use differentiation
 
Try thinking this way: there are many ways that the bird could have flown the 50 meters in 3 seconds. It could have rapidly accelerated to say 17 m/sec and flown the whole way there at that speed, and then quickly slowed down at the end. Or it could have gradually accelerated through the first 25 meters and then gradually slowed during the final 25 meters. Or it could have done a crazy flight speeding up and slowing down repeatedly. So as the others have said, the 50/3 = 16.7 m/sec is just the average, and to find the acceleration you need to know the actual location at each point along the way. (That's azureth's function; f(t)).
 
Because v=s/t gives us the constant value and derivation of constant value gives us ZERO answer.
 
but if i use equation of motion
2as=vf^2-vi^2
it give me some answer like 2.78m/s^2 :confused:
 
otomanb said:
but if i use equation of motion
2as=vf^2-vi^2
it give me some answer like 2.78m/s^2 :confused:

vi = 0, but you don't know vf

you'll have to use another constant acceleration equation, s = vit + 1/2 at2 :wink:

btw, is this a rocket-powered bird?

what makes you think it flies with constant acceleration? :biggrin:
 
  • #10
not constant acceleration with constant "Velocity" and if velocity is constant acceleration is always ZERO
 
  • #11
i'm confused …

then why did you use a constant acceleration equation? :confused:
otomanb said:
but if i use equation of motion
2as=vf^2-vi^2
 
  • #12
2as=vf^2-vi^2
sorry don't know that it's constant acceleration equation
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 23 ·
Replies
23
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 8 ·
Replies
8
Views
1K
  • · Replies 25 ·
Replies
25
Views
4K