Question

A bird can fly 24km/h .
Part A
How long does it take to fly 3.1km ?
Express your answer to two significant figures and include the appropriate units.
Δt =

Answer 1

Hi! I have about 10 minutes, but this is a simple problem after you see what to do. Do you know how to start?

Answer 2

no I dont I know that there is formula but dont know which to use

Answer 3

Well, first you need to identify what quantities you have! What is 24km/h?

Answer 4

is that the speed?

Answer 5

Yep! What is 3.1km?

Answer 6

distance?

Answer 7

Right! And what do you want to find?

Answer 8

time

Answer 9

or is it change in time bc its delta T

Answer 10

Right. I agree! :)

And you could say it's also the change in distance. (Side note: this is still not a vector.)

So you have speed, distance, and need time. You must find or create an equation that has only \(v\), \(d\text{ or }\Delta d\), and \(\Delta t\).

What is the definition of speed? Change in distance per time! \(v=\dfrac{\Delta d}{\Delta t}\implies \Delta t=\dfrac{\Delta d}{v}.\)

Answer 11

Now do you see what to do? I must get going. Take care! :)

Answer 12

ok i will try to figure it out thank you!

Answer 13

Hi! I used the definition of speed, and wrote it in math! Then I used algebra to solve for \(\Delta t\). Now we substitute in our values for speed and distance to see that\[\Delta t= \frac{\Delta d}{v}=\frac{3.1\ [km]}{24\ [km\ /\ hr]}=.1291\bar 6\ [hr]\]

So, that is the time! Notice that I included the units.

Now, we need to round it to two significant figures. That is, our answer should be \(.13\ [hr]\). Now, that doesn't show what significant figures are. If you're unsure, just do a search of ask! :)

Answer 14

oki thank you, I actually got that but I forgot to close the question..silly of me...thank you!

Answer 15

I'm glad you got it! You're welcome! :)