Average velocity
What is the difference between average velocity and the instantaneous velocity mentioned in the
homework.
Do we mean that if an object travels x distance in y amount of time in a particular direction and then the
same x distance in the same y amount of time in the opposite direction, its average velocity will be zero?
Although it did have some speed while it travelled in both directions.
Is the difference between velocity and speed just a matter of displacement?
If velocity is calculated by using displacement (a vector), would that mean that it is necessary for time to
be a vector as well? If it is, then how can speed be calculated when you divide distance over time? Can
time be both scalar and a vector?
Why is the difference between displacement and total distance traveled so important (velocity vs speed)?
Can you find the velocity by determining the derivative?
Is average velocity really useful to calculate if at times you end up back where you started and it seems
like your velocity was 0 because your final position was same as your initial position? Isn't there a way to
account for this?
when a dog is moved from point a to b and then back to b, 1) is the area under the speed zero?2) also
the distance traveled is not zero, so do we have to break down intervals ?
What is the difference between average velocity and constant velocity?
I realize that the average velocity is how far something moves over how long it took it but would then is
there anything that would be considered just "velocity" not average velocity or are they synonymous?
Velocity versus speed: could you explain a little more about the example of running around the 400m
track with average velocity versus average speed?
What do the colored areas under the curved graph represent? I am having difficultly interpreting what is
written.
I understand velocity, no question
It seems like it could be misleading to use velocity and displacement (vectors) in a lot of cases, like in the
Garfield example. What is the benefit of looking at average velocity when it could obscure speed if
someone or something is not moving in a consistent direction? (instantaneous velocity makes more
sense to me)
Could you calculate the average velocity by taking the integral of a given position/time function?
Does velocity always involve a sense of direction, aka magnitude of direction, whereas speed only
depends on how fast you were moving even if you ended up in the same spot you started?
What is the method for adjusting the line on a position graph so that it is constant and the area beneath it
can be taken to determine the change in position?
When talking about average velocity the idea of constant velocity came into play. If we are considering
realistic situations, as in a runner on a track, we understand that they are not likely maintaining a constant
velocity throughout the entire length of the track. That considered, should we be at all concerned about
the assumption of constant velocity? Or remain focused on the final and initial time, and displacement?
Even though average velocity has a direction associated with it, and if you run a lap, your average
velocity is 0, you can still fine an average velocity you ran, can't you?
So since velocity represents a direction, then is it possible to have a negative velocity? Or would it just be
represented by saying something like "the boat traveled south at 20m/s"?
Why is the distance or delta(x) given as the area under the curve of a velocity vs. time graph?
If average velocity is based on displacement, then is velocity based on distance?
It wasn't clear why the pink area on the graph under "average velocity graphically" could not be included
and why the light blue area is.
Does this mean that if an object travels farther during the same amount of a time as another moving
object, the first object has a greater average velocity?
Will average speed and average velocity of a vector always be the same if the starting and end position is
NOT the same?
I don't understand the difference between displacement and total distance. Isn't the displacement the
same thing as the total distance but indicated on a graph instead?
Does speed relate to a derivative as velocity does?
When you add vectors, do they have to have the same units?
How does dealing with velocity as a vector rather than just conceptually imagining it allow you to "do
much more"?
Do velocity and speed always have the same number quantity?
To clarify, does "r" represent the distance in the equations given in the article?
Is average velocity the same as speed?
Is it possible to obtain a negative average velocity? If so, What does that say about the change in
position?
If a vector is essentially speed with directionality, so (conceptually speaking) would velocity be a type of
spped but speed would not be a type of velocity?
Why is distance displayed as L in the equation [v]=LT? a
Is the way to solve for average velocity on a graph just to use the slope of the triangle formed between
the 2 positions and times?
Does average velocity need a position to it? I always learned that acceleration was used with vectors
because it tells you if you are speeding up or down (positive or negative), but not velocity.
How exactly are position-time graphs and velocity-time graphs related? How do we use derivatives and
integrals to see this relation?
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For average velocity, our formula is (average velocity) = (change in position / change in time). For
instantaneous velocity, would we be using the derivative of the position equation, or is there another
formula to use for that?
If we can only add vectors to another vectors, can we also multiply them together
If dx is a pure number and it is very big instead of very small, can it still the formula for derivatives still be
derived?
Isn't it misleading that average velocity can be zero when the start and ending position are the same,
even if the object or person moved? How does the average speed give more information as to the
movement of the object, even when it uses less information in its equation?
Is the only difference between speed and velocity that velocity has direction?
If an object that moves from its starting position and then returns to it has an average velocity of 0, does
this mean that on a normal day a person has an average velocity of zero because they, usually, start and
end the day in their bed? Does the path an object follows on its return to its starting point have to match
its path away from the starting point in order for the average velocity to be 0?
I really do not understand the overall point of average velocity. As mentioned in the reading, if you run
and then return to the starting point, average velocity is 0. Why can you not just use displacement instead
of average velocity?
How can the concept of velocity be applied to the real world? It seems that in our physical world, we are
more concerned with speed rather than velocity. For instance, we can think of the speed of a car, or how
fast a track runner is running.
The last paragraph of this reading points out a quality that makes velocity fallible, but velocity is almost
always used instead of speed in the physics that I have encountered. Are there ever instances when we
use speed instead of velocity?
When calculating the average velocity of something, is it reasonable to change the variables to represent
the object/time that you are measuring?
If an object travels x distance in one direction and then travels the same distance, x, in the opposite
direction at a faster velocity, would its average velocity still be 0?
When will it be most useful for us to represent average velocity graphically?
Does the average velocity always depend on what the vector displaced, even when you don't know where
the vector ended?
In the reading it states; "A displacement in the x direction can never cancel a displacement in the y
direction. So we can conclude that the things multiplying the i must be equal and the things multiplying
the j must be equal." Can you clarify why a displacement in one direction being unable to cancel out a
displacement in another means that the things multiplying the i and j must be equal?
How do you divide a vector by total time to find average velocity?
When doing derivatives graphically, why do we have to adjust the position of the constant v line so that it
has the same area under it? This is referring to when going from a velocity graph to a position graph.
Why do we describe velocity as a vector? Isn't better to say that velocity is a vector divided by the change
in time?
Could you also write ri-rf/ti-tf for finding the average velocity?
Will distance always be labeled L or will it sometimes be labeled d?
Average velocity times time gives the total distance travelled, but if we returned back to the starting point,
the total distance travelled would be 0?
How is it beneficial to use velocity when it can give a answer of 0 even if some distance is covered over a
period of time? Are there real life examples in which velocity is not useful?
What is the purpose of defining the average velocity equation by the time interval?
Is there a universal unit that velocity is measured in? miles/hour, feet/second? Is it based on the problem
given or is there a special physics work for velocity?
If speed is scalar, and velocity is a vector, is acceleration also a vector?
is the instantaneous velocity related to the instantaneous speed? if so, how?
Why is there a focus on average velocity instead of instantaneous velocity?
Is the tangent to the curve seen in the graph linear?; Is the discussion of the shading beneath the v line
solely a method of calculating the area under the line according to whichever time interval is being
measured?
Can the terms "velocity" and "speed" be used interchangeably in other subjects besides physics?
Under the sub section: Average Velocity Graphically, what is the distinction between delta(x)=(v)delta(t)
and average velocity = delta(x)/delta(t) because both the middle and last graph show the same areas. So
are they pretty much the same equations?
Will we see more commonly problems where the velocity is constant or more where they are not
constant?
Why are vectors like dimensions?
How is "how far did you move" different from "what is your vector displacement"? I assumed they meant
the same thing.
Would the average velocity of blood traveling in the bloodstream (assuming it is a "perfect" circuitous
system) be considered 0? How is displacement measured when the object is in constant motion?
Are there other ways to find the change in position if a velocity-time graph or the velocity function were
not given, and if so, which other functions could help determine the change in position?
In the text, it is said that the average velocity can equal to 0 if, for instance, you move certain distance to
the positive direction and return to the orgin of the starting point (negative direction). I don't understand
how velocity can equal to 0, when the object obviously made its move. Can you please explain this
further?
Can we ever measure the average velocity using the instantaneous? Also if the average velocity is
calculated using a uniform velocity is it equal to the change in time?
How do we account for the fact that sometimes displacement ends up being 0 because the final initial
sometimes cancel each other out when there was in fact a velocity?
If you do the absolute value of the average velocity, would that give you the speed, using the track runner
as an example?
This article describes the idea of average velocity and it seems as if there are multiple connections
between average velocity and the derivative. How are the two related?
In real life situations (for example, a car ride), speed is more commonly used than velocity because going
from one place to another does not always have a clear route (ie. mountains, hills, etc). Thus, in example,
a car is moving from point A to point B, but it requires a series of twisted routes with no possible way of
going straight to the next point. Then, how in this case would velocity be useful when the most straight
displacement (point A to point B) is impossible?
Will we use scalar quantities like speed in this class? Or will we only deal with velocity and vector
quantities?
In the cartoon, when Odie was kicked didn't he have a velocity? I don't understand how going back to the
start negates the velocity he had when he was moved.
When do we use the delta symbol as oppose to indicating initial and final values when writing out
equations?
How would instantaneous velocity be calculated? How does this differ from average velocity?
Is it best to think of the average velocity as the change in position over a time interval an the
instantaneous velocity as the position at a particular time we are looking at?
Instantaneous velocity was a follow up link-When calculating instantaneous velocity are you calculating
the the slope between two points of infinitesimally so small distance, so small that you can consider them
a singular point in time?
If velocity only takes total displacement into account, why would we ever use it? Wouldn't it be more
useful to use the idea of total displacement for the direction of the vector and use the actual distance
traveled?
I understood velocity thoroughly until the post stated "equation doesn't capture everything we are thinking
about when we talk about velocity." Is this related to how physical concepts must be separated from
mathematical concepts? I find myself mixing the two either way and not finding a way to mesh both
besides putting a numeral value and letter together. Velocity isn't discussing speed, but the change in one
point to another? If the equation of velocity is (how far)/ (how long) then, what's the difference between
the speed unit (m/s)?
Could we compute average velocity from the average of all instantaneous velocities recorded?
Does the amount of times that the direction of the object changes affect the average velocity?
Whenever we are referencing the velocity equation, is it necessary to incorporate the vector notation?
For something like the speed of light, the average velocity is half of its actual speed because it is only
going either 0 or its maximum speed. There is no build up or acceleration. So in this regard the average
speed is a misleading number to use because it does not accurately translate distance traveled in a
certain amount of time. So in that regard is average velocity not useful for calculations?
How are derivatives related to velocity, I still don't get that?
Do we just accept the fact that average velocity doesn't account for how we got from the starting point to
the finishing point? Is there any way we can account for something like the Garfield cartoon, where the
dog's velocity would be 0 despite him having moved?
What is the point of calculating average velocity when the net displacement does not change
Is it possible for velocity to have a negative value?
Velocity and speed are used interchangeably in many instances, but when would one description be
better used in the other? Would direction be the only determining factor?
Why do we limited to use a velocity when calculating a derivative and not speed?
By describing velocity as a vector-valued function it seems like one can arrive at some interesting but
erroneous conclusions about physical events. For example, Odie's movement in the Garfield strip.
Though he returned to his initial position and consequently had an average velocity of 0, this does not
really make sense and is of no interest in describing how fast he moved while being kicked. How do we
know to whether or not we need to differentiate between these two perspectives (average vs.
instantaneous) when describing physical phenomena appropriately?
In the example of going around a track, if you ended up just short of your starting point would your
velocity include the speed and direction of going almost all the way around the track or would it be
negative as if you just took a few steps backward instead of running all the way around?
If velocity is measured using two dimensions, how could it be graphed and interpreted in 3D spaces?
If you went 5 miles one way and then went back to your starting point, why wouldn't the average velocity
be the average time it took to get to the 5 miles, averaged with the time it took to travel back? Because it
doesn't make sense for velocity to ever be zero?
How useful can average velocity be if, according to average velocity, in the cartoon the dog did not move,
even though he did? How small do your measurements have to be to reliably account for all the
movements of an object?
How is average velocity the same as displacement?
Why does <v> have an arrow on top of it, indicating direction, but [v]= L/T doesn't?
A lot of physics seems to deal with velocity and displacement, so does that mean we will never have to
calculate the speed of something, and instead just find its velocity?
in the Velocity versus speed, 20m/s in some direction is velocity and 20m/s is speed, is the only
difference between the two the direction its going in because word scalar threw me off?
If the average velocity over a time interval is the change in position divided by the time interval and the
instantaneous velocity is is the change in position during a particular instance, then is average velocity
literally just an average of many instantaneous velocities?
what do you mean that if we make the time interval small the slop becomes the slope of the tangent to
that position curve?
Since velocity is a vector, can there be a negative average velocity? If so what does that indicate?
How would you write velocity in vector form if velocity is a vector?
For a graphical representation of Velocity vs. Time, how do we know when to slide the average velocity
line? Is it just in cases we have constant velocity?
Why can velocity have dimensionality? When you express velocity as L/T, can you not just always divide
L by T and just have the one value? Why should we care about the dimensionality?
Why would be try to find the best fit line for average velocity on a graph if we can just take the initial time
and distance and the final time and distance and figure out the velocity from that
It seems that speed has less valuable information to present than velocity, considering the fact that if an
object were to end up in the same place that it started, the velocity would be zero. Is there any
measurement to combine the two to give more useful information, or is that simply a longer explanation?
can we just think of velocity as speed in a +/- direction?
Will we ever have to use estimation for finding velocity?
Are you allowed to use average velocity in calculation when this would be zero while the average speed
was above zero? Should you generally include the speed to indicate that there was a displacement?
How do you convert between position and velocity graphs?
If the symbol for velocity is a "v" with an arrow on top, then does that mean the symbol for speed would
be a "v" without an arrow on top (because speed is scalar and doesn't have a direction)?
For the purposes of our class, does speed not mean change in velocity, I thought that speed and
acceleration were one in the same?
Even though it is a vector do you always have to specify a direction when talking about velocity?
Can we tack on negative and positive symbols to our velocity in order to indicate a direction?
If velocity is a vector that always requires both a magnitude and direction how do we determine the
specific direction an object is going off of a velocity over time graph?
What is the purpose of taking position so thoroughly into account when determining velocity, so that the
velocity is said to be 0 when the object moves but starts and finishes in the same spot? Why not just use
speed, so that the motion of the object is what really matter?
Would it be more accurate to calculate the average velocity of an object by calculating the average
velocity of the object at several points in time versus just calculating it at 2 points in time?
What is so important about average velocity?
It was stated that velocity only pays attention to the beginning and end position (how big the change in
position was). If you were running in a large circle, say around a track, and you finished couple steps past
the position you started, is your velocity only accounted for in those few steps?
The example of the Garfield cartoon shows that Odie has a net velocity of zero because he is kicked back
to where he started. Does this mean that if you give a person enough time, they could travel somewhere
far away and then come back days later, yet have a net velocity of 0?
Does the idea of velocity apply to acceleration in the same way with slight differences?
Since all velocity must have a distance, why is that often not defined in problems using velocity? and
would that just instead be speed?
How would we express the velocity of a vector that is travelling only vertically on a graph?
Let's say you ran around a track (400m) in 60 seconds. Would your average velocity by 0 m/s since there
is no displacement from your start point and your end point?
If we are asked a question in the future about average movement of an object that moves around and
returns back to its starting position, should we use distance over time to find the average speed of the
object, or displacement over time to find the average velocity?
how would velocity be helpful if the motion was happening in a cyclic form? For example, why would you
use velocity to measure the rate of blood flow in the human body? .. technically, the answer would be 0,
right?
Why do we have to indicate the direction for velocity? Why does it matter?
Why and when do you need to use this second equation, ?x = <v>?t?
X is usually associated with distance. However, in this instance it looks like r represents distance in the
first equation. Is it what is meant by different variables can have different meanings?
is there a difference between position and direction?
Im not really sure what the dark blue area graph is representing. Would you please briefly go over it?
Will velocity and speed ever mean the same thing in physics, or will velocity always be associated with a
direction?
In the reading, why was it necessary to adjust the constant velocity because the average velocity was
constant over the given time interval so that it has the same area? Is it because average velocity and
constant velocity are equal as long as the velocity doesn't change at all? Also why is <v> interpreted on
the position graph and the second equation given is used to go from the velocity graph back to the
position graph?
Given that I moved a distance delta r in a time delta t, the average velocity tells us the constant velocity
that one would have to move to go that distance in that time. However, it's possible that I didn't move at
that constant velocity. So how does the average velocity help me understand my movements, or in other
words, why is it useful?