AP Notes, Outlines, Study Guides, Vocabulary, Practice Exams and more!

# Some Physics Problems....

14 posts / 0 new
Offline
Joined: Sep 2005
Some Physics Problems....

O.K this is not really for A.P Physics.....but it is Physics none the less.....
-Would anybody mind solving or hinting clues on how to solve these problem....
-I shouldn't be to hard....for me yes I suck at math.....(next time i'll pay attention in class)

"Harry Hopeless averages 40km/h for the first half of his car trip. How fast should he drive on the remaining half of the trip to have an average speed of 80km/h for his trip."

U know what thats the only one I'll post....I should face the consequences for not paying attention in class....I'll try to figure out the rest of my problems by myself....sorry if administrators feel this as a wasted thread....

Offline
Joined: Sep 2005

120 mph ;)

Offline
Joined: Sep 2005

Wow...really....hmmm let me work my way backwords

*takes pen and writes answer on paper then walks away from room* :)

J/K Thanks though.....

Offline
Joined: Sep 2005

Well think about it, there's not much to it. I'm sure you thought it was harder than it really is and so you had a brain freeze.

What number, when added to 40, gives you an average of 80?

40 + 120 = 160

average is 160/2 = 80!!!!!!

Voila

Offline
Joined: Sep 2005

Also, if you have any others feel free to ask.

Offline
Joined: Sep 2005

I see....I guess I'm just stuck at using formulas provided by the teacher....So I try to apply one of them to these stupid problems....

Edit: *Really Cool K....one more and thats it

"A train moves at a constant of 60km/h towards a station 30 km away. At that moment Fanny Fastbird leaves her perch on the locomotive and flies toward the station at a constant speed of 100km/h relative to the ground. When the bird reaches the station, she immediately turns around and flies back to the train at the same speed. When reaching the train she again immediately turns around and flies back to the station, repeating the process until the train passes the station. What is the toal distance traveled by the bird?"

Offline
Joined: Oct 2005

THAT IS WRONG. Lets say his course is 80 km, then he will spend one hour going 40 km/h and then go 20 min at 120 km/h, that means that he would have gone 80 km in 4/3 hours which means his average speed is 60 km/h. It is impossible to double your average speed when the trip is half over. Let me show you, lets say his trip is 240 km. That means it will take 3 hours to get half way at 40 km/h, now he must complete the rest of the trip with his average speed 80 km/h, which means that it should take 3 hours to go 240 km. So he has to go the rest of the trip in an instant to get an average speed of 80 km/h, so even if you could go the speed of light, you can't double your average speed after the trip is half over

You know you're an AP student if...

you think studying is fun.
you constantly find yourself saying "we had homework?"
everything you know about sex, you learned in english class.

If you try to fail, and succeed, which have you done?

Offline
Joined: Sep 2005

If I run a 1 km race and go 1km/hr the first 500 meters then 100 km/hr the other 500 m I have more than doubled my average speed.

;)

Offline
Joined: Oct 2005

No you haven't because you will take half an hour to go the first half and then you will take another 18 seconds to finish the race. So tell me what your average speed is. 1km/(1/2 + 1/200 hours) correct, because the total distance is one km and the time is 1/2 hour + 0.5/100 hours, which gives you an average rate of 1.98 km/h. Let me think...I don't think you can ever double you average speed once you have done half. Although I understand what you're thinking, if you run for an hour at speed 1 then you run for an hour at speed 100, then you will get an average of 50.5, although that means that you had only completed 1/101 of your race when you switched speeds. Sorry I couldn't do you train problem. I ran out of time and it is really hard. I kept getting 34.8 which is obviously wrong. Sorry I can't be of more assistance

You know you're an AP student if...

you think studying is fun.
you constantly find yourself saying "we had homework?"
everything you know about sex, you learned in english class.

If you try to fail, and succeed, which have you done?

Offline
Joined: Oct 2005

if you guys realy want me to, I can and will create a Physics site with ALL forumals n descriptions as well as other items included (this shall make your physics class ALOT more easier).

[URL=[/URL]">http://www.apmastersite.com][IMG]http://img235.imageshack.us/img235/1351...

Like my Signature Picture? Then Click On it!!
[URL=http://www.hostunlim.com/apfaq]My New WebPage For AP Students[/URL]

Offline
Joined: Sep 2005

that sounds cool......it would help me a lot since i'm bad at math and things of that nature.......if u want to make it.....that would be cool

## Need Help?

We hope your visit has been a productive one. If you're having any problems, or would like to give some feedback, we'd love to hear from you.

For general help, questions, and suggestions, try our dedicated support forums.

If you need to contact the Course-Notes.Org web experience team, please use our contact form.

## Need Notes?

While we strive to provide the most comprehensive notes for as many high school textbooks as possible, there are certainly going to be some that we miss. Drop us a note and let us know which textbooks you need. Be sure to include which edition of the textbook you are using! If we see enough demand, we'll do whatever we can to get those notes up on the site for you!