[ashlayy101]

A jogger jobs around a circular track with a diameter of 880 meters in 40 minutes. What is the distance around the track?

[Unknown008]

You need to know that the perimeter (or in this case, circumference) is given by:



but since diameter = 2 radius,



Can you post the answer you get?

( is approximately 3.14)

[ashlayy101]

19.7??

[Unknown008]

Hmmm...

Perimeter = 3.14 x 880 = 2764.6 m

or you didn't mention something about the time given?

[ashlayy101]

The whole problem itself is this...

A jogger jobs around a circular track with a diameter of 880 meters in
40 minutes.
(a) What was the time in seconds?
40 X 60=2400

(b) What is the distance around the track?

(c) What was the runner's average speed?

(d) What was the runner's average velocity?

The rest I cannot figure it out

[ashlayy101]

I have no idea how to work out any of the problems! (really bad at math sorry)

[Unknown008]

That's okay, we're here to learn right? :)

Okay, the circumference is indeed 2764.6 m.

You need to multiply (which is 3.14) by the diameter of the path, that is 880 and that's it!

Now for the next part, speed is given by:



Can you work this out now? :)

[ashlayy101]

1.1519?

Also, I had followed your steps above and I had gotten 2763.2 may I ask if you rounded?

[Unknown008]

I actually took the complete value of which is 3.1415927. I don't know what your book/question asks to use as when it comes to the value of pi. But if you got 2763.2, that's good too but you must say that you took pi as being 3.14 like this:

Taking as 3.14,

Distance of track = 3.14 x 880 = 2763.2 m

Now, there is something called significant figures. Usually, you put your answer in the same amount of significant figures (sf) as in the given problem, or one sf better. In this one, the highest sf is 2 because of '880'. Hence, you can put your answer this way:


Distance of track = 3.14 x 880 = 2763.2 m = 2760 m (3 sf)

But that doesn't matter much and let's continue. I'll take your value for the distance.

~~~~~~~~~
Speed = 2763.2 / 2400 = 1.15 (3 sf)

Ok, good! :)

Last part now. Velocity is defined as the rate of change of displacement, that is:



Displacement now is the distance from the starting point to the finishing point. Can you find this distance and post the velocity? :)

[ashlayy101]

I some how got 0 and I do not even know how I did that. But, I had thought I had a different answer and so I started typing. Well, the first number I put in was 0 and all the sudden a green check mark pops up saying it was correct? I don't know what I just did. (haha)

[Unknown008]

That's correct! :)

Yes, the velocity is really 0. This is because the jogger is back at his starting point right? It is a circular path, he ran around it and came back to the starting point. So the displacement becomes zero. No matter by what you divide zero, you'll get zero again, so, the velocity is zero!

Well done! :)

[ashlayy101]

Awsome! Thank you so much you don't know how stressed I was because my teacher just was not explaining it like you just have! He didn't sit down and explain anything! I really truly appreciate it =]

[Unknown008]

I'm glad to help :)

If you have more problems, you can ask! :)

[ashlayy101]

If you don't mind? I am stuck on this last problem of my homework, just like the problem above after 2 days, still have not yet figured it out!

A space probe of the surface of Mars sends a radio signal back to the
Earth,a distance of 8.86 x 1010 km. Radio waves travel at the
speed of light (3.00 x 108 m/s).


(a) How far away is the space probe?


(b) How many seconds does it take for the signal to reach the Earth?


(c) How many hours is this?

[Unknown008]

a) The distance from Mars to Earth is how much? Where is the space probe?

b) Use the formula for speed that I gave you earlier.

c) The time you got is in seconds. Convert this in hours.

Can you give it a try? :)

[ashlayy101]

Yes I will try and if you don't mind respond back to make sure I did it right?

[Unknown008]

Yes, given I see your response in time. I just took lunch, and this is why I took some time in replying you back :o

[ashlayy101]

For "A" I got 2.658?

[Unknown008]

Let's take it this way.

My computer is besides me. I am 2400 km away from you. How far is my computer from you?

[ashlayy101]

2.4ft?
I believe I would divide 2400 into a 1000?

I am so confused please bare with me