Question

What's the difference between instantaneous and average velocity? How do you calculate both of them?

Answer 1

Instantaneous velocity is calculated at a specific point....average velocity is calculated over a distance...

Answer 2

Instantaneous is the velocity at one instant.. average is like hero said.. is calculated over the period of travel..

Answer 3

So if they ask what the average velocity is after 2 minutes?

Answer 4

I don't just plug in 2 into my velocity function, right?

Answer 5

If you have the formula for average velocity, use that...

Answer 6

So if I had v(t)=16t^2-14t, just an example how would I get the instantaneous versus the average with that?

Answer 7

Lets say i was taking a ride in my car to another city, and I drove for an hour. If the other city was 60 miles away, that means my average velocity would be 60 mph. But, during that trip, I got caught in a traffic jam, where at some point in time i was going 20 mph. That would be an example of instantaneous velocity.

Answer 8

so I would get the acceleration function first?

Answer 9

Emily stop posting in other people's posts

Answer 10

Ok, I understand the concept, just not the math

Answer 11

Oops, just evaluate at t = 2

Answer 12

Like would I take the average of v(0) and v(2) to get that average velocity? Like if t=2 secs?

Answer 13

don't take a derivative, sorry

Answer 14

If you want the instantaneous velocity at time t, plug t into your velocity function. If you want the average, i believe you integrate the velocity function with respect to time, use t =0 and t = t_max as your limits of integration, then divide that answer by the time ellasped.

Answer 15

You have the function for velocity...all you have to do is plot it and take two points and use the formula for average velocity to find displacement/time

Answer 16

well, I have the position function already...

Answer 17

The integral should give you the distance traveled, then dividing by the time gives you the average velocity.

Answer 18

oh, if you have the position function, then its not hard, just plug t into that and divide by t.

Answer 19

I don't understand?

Answer 20

Do we have a function to work with by any chance?

Answer 21

yes s(t)=16t^3+12t^2-144t

Answer 22

Alright, lets say i wanted the average velocity at t = 5

Answer 23

ok

Answer 24

First I calculate s(5), then i would divide that by 5. Let me get some numbers, one sec

Answer 25

\[s(5) = 16(5)^{3}+12(5)^{2} -144(5) = 1580\]
So the average velocity would be :
\[1580/5 = 316\]

Answer 26

in whatever the units are supposed to be (ft/sec, mph, m/s, etc)

Answer 27

oh ok

Answer 28

For instantaneous velocity, we would need the velocity function, and you would plug t = 5 into that.

Answer 29

awesome! THANK YOU!