Anyone out there good at physics?

T

the1brock

CAGiversary!
Feedback
1 (100%)
Struggling with a physics problem and its due early a in the morning. It goes like this...an average family of four uses roughly 1200 litres (300 gallons) of water per day. (1 litre=1000 cm cubed). How much depth would a lake lose per year if it uniformly covered an area of 50 square kilometers and supplied a local town with population of 40,000 people? Consider only population uses and neglect evaporation and so on.

I have got it to 1.2 X 10^10 cm^3 for the use of water in the population per day...not sure if that is even right but I do not know how to relate that to the area of the lake.

Sadly, I think this is a basic problem seeing as it comes out of chapter 1 but I do not have the book because it costs too much.

Can anyone help?
Thanks in advance to anyone that at least takes a crack at it

Oh and there is another that looks to follow the same format...A heavy rainstorm dumps 1.0 cm of rain on a city 5km wide and 8km long in a 2 hour period. How many metric tons (1 metric ton=1000 kg) of water fell on the city? (1 cm^3 water has mass of one gram)
 
[quote name='Graystone']Only thing I know about physics is that if someone forcefully swings their leg toward your nuts, it hurts.[/quote]

Don't forget that if an apple falls off a tree, it comes down towards the ground rather than upwards toward the sky.
 
Did you google the problem? If it came from a textbook, you can probably buy the solutions somehow over the net. Also, google the book's name and author, and find a school website that posts those solutions.
 
[quote name='LiquidNight']those aren't physics problems, they're geometry.[/QUOTE]

While this isn't physics, it isn't geometry either. This is a simple unit conversion problem which is typical of an early physics course. These are just the basic mathematic principles that you are going to be using in actual physics problems OP. Just keep track of your units and in the end they'll all cancel out except for a depth (cm or meters or whatever you want it to be).
 
[quote name='jbroush99']Don't forget that if an apple falls off a tree, it comes down towards the ground rather than upwards toward the sky.[/QUOTE]

YOU LIE!
 
Shipwreck is right, these are just basic "unit" problems. This stuff is typical of physics beginner problems that aren't really "physics" related.

Keep in mind that you first need to calculate the volume of water that is used by the population. You know the area of the lake, so you only need to solve for the depth....not too hard once you know how much water is being used. The trick is to convert the volume to the right units.

The second one is even easier....I'll give you a hint. The two hours mentioned doesn't figure into the solution in any way.

TBW

PS Find the money to buy the book, if you're an engineer, its one that you will probably want to keep. I wish I had mine.
 
Thanks for the messages guys. I found this place cramster that had a couple of hints as well. The second problem was even easier, I just didn't know where to start. Thanks again guys.
 
Ugh, I took Honors Physics my senior year of high school, the teacher thought he was Isaac Newton or something, and always tried to talk in a way that made himself seem smarter than he actually was. I hated him.

I don't understand why people do that, I consider myself to be pretty damn smart, but when people try to use a vocabulary simply to make themselves sound smarter, well, I find that to be quite ridiculous.

Needless to say the guy couldn't name one player on any local sports team. He definitely turned me off to Physics.
 
[quote name='Graystone']Yes? no wait, unh I don't remember how the witch trails worked :)[/QUOTE]

The laws of physics clearly state that if a woman floats, she is indeed a witch. If she sinks to the bottom of the lake, she is just dead... until she floats to the top, then she's a dead witch.
 
[quote name='shipwreck']The laws of physics clearly state that if a woman floats, she is indeed a witch. If she sinks to the bottom of the lake, she is just dead... until she floats to the top, then she's a dead witch.[/QUOTE]
Whoa, physics said that? Then it must be right, and I am a witch :lol:
 
You must log in or register to reply here.
bread's done
Back
Top