# Mathematics

### #1

Posted 18 August 2001 - 12:42 AM

i want to know who does and what branch of it.

and maybe we can challenge each other with questions and problems.

what do you think???

### #2

Posted 20 August 2001 - 08:56 PM

here is the first question for you:

"how many members are they in our forum?"

more seriously, i'll be back with real questions.

### #3

Posted 30 August 2001 - 12:46 AM

Calculus is my area of study for now

I'm ready for a challenge any day hehe

### #4

Posted 30 August 2001 - 02:23 PM

Fire away with a question or two, Martin!

Mike

### #5

Posted 30 August 2001 - 06:38 PM

i hope i'm going to like it because i like everything else i learned, especially Calculas.

Armo, where do you take Calculas? in college or high school(AP class)? and what kind?

### #6

Posted 30 August 2001 - 07:04 PM

-----

a helicaptor is flying horizontally over road with amplitude of 50 meters. it's speed is 25 meters per second.

there is a car coming toward it on the road.

the radar on the helicaptor shows 50 meters per second and 150 meters of distance between the car and helic.

what is the real speed of the car???

------

here, i'll try to draw a picture to help you.

.....H ----> 25 m/sec

....|.

5..|.. 150 m

0..|...

m..|.............pic is not drawn to scale

....|.............pls, discart all the dots

....|......

______<?C_____

the rest of the action figure out yourselves.

----

have a good time with this one.

sorry, for any inconvinance with numbers. i made them up myself

[ August 30, 2001: Message edited by: Harut ]

### #7

Posted 31 August 2001 - 08:12 PM

### #8

Posted 12 September 2001 - 11:30 PM

asum es 75? hmmmm

Mos, ko matemi dasatun ova eghel, Mos???

sorry Mos, it's not the answer. it's not that simple. you have to do some calculation.

i see nobody else is interested, so i'll just go ahead and try to solve it myself.

i'll have the answer shortly.

### #9

Posted 12 September 2001 - 11:51 PM

-----

a^2+b^2=c^2

50^2+b^2=150^2

b^2=22500-2500

b~=141.42

(a(t))^2+(b(t))^2=(c(t))^2

taking derivative

2a(t)*da/dt+2b(t)*db/dt=2c(t)*dc/dt

2's cancel out

a(t)=50

b(t)=141.42

c(t)=150

da/dt=0

db/dt=25+?(car's speed)

dc/dt=50

50*0+141.42*(25+?)=150*50

3535.5+141.42*?=7500

141.42*?=3964.5

?~=28

therefore the speed of car was, approxematly

28 meter per second.

-----

how was it.

i hope your were confused and my colculations were correct.

have a good time.

[ September 12, 2001: Message edited by: Harut ]

### #10

Posted 26 September 2001 - 03:36 PM

Here is a simple(kind of fun) question for you?

A billiard ball is struck so that it strikes all four cushions and returns to its starting position. In what direction is it struck, and how far does it travel?

I will post the answer tomorrow.

Azat

### #11

Posted 26 September 2001 - 08:21 PM

let me think. i'll reply shortly , if i can.

### #12

Posted 26 September 2001 - 09:19 PM

On 3 corners you place balls (one each). On your left hand side you place 2. You start the game by striking one ball onto the other, which has to travel straight forward and strikes the ball in the very next corner(vertical), continously travels straight line onto the parallel corner, strikes the ball standing there and vertically to you right hand side, where the lonely ball stands, strikes that too and comes to the starting point: Jlump! into the hole!

If you know the curcumference (?) of the table, then you will know how many meters ball has travelled I guess

Is my calculation make sense Azat

### #13

Posted 26 September 2001 - 10:03 PM

here is mine.

______________________

|41|

||

|52|

||

|63|

-------------------------

the ball is in the center(0). you hit it so it goes to 1, bounces to 2, then 3,4,5,6, and back to 0.

this might not be correct because it hits the longer sides twice. but if there is not limit then this works.

if we suppose the play area is 2x4, then the ball has traveled 8 times squre root of 2.

### #14

Posted 27 September 2001 - 10:31 AM

I was thinking much simpler and I did confuse you by not telling you that the ball must hit each cushion once.

You were on a good thought process though.

Here is the answer that I was thinking.

It must be stuck parallel to one of the diagonals, and its total path back to its starting point is double the length of a diagonal.

Azat

### #15

Posted 27 September 2001 - 10:50 AM

i couldn't think of that.

it's pretty clever.

more questions please.

### #16

Posted 27 September 2001 - 12:23 PM

We each have a watch and it reads 12 o'clock on it right now. My watch is 1 minute too fast per hour, and your watch is 1 minute too slow per hour.

When will our watches read the same time again?

### #17

Posted 27 September 2001 - 12:29 PM

### #18

Posted 27 September 2001 - 12:51 PM

--

i didn't really think about this one.

i guess it would be 30 hrs later.

am i correct?

### #19

Posted 27 September 2001 - 02:08 PM

it's 360 hrs later.

### #20

Posted 27 September 2001 - 05:07 PM

Here are 2 more

1. Two strangers from different parts of America both build similar apartment buildings in their home towns. By chance, they both forget an important part of their project. They each, once again by chance, call the same national hardware store and order the missing items. The prices they are quoted are as follows:

one will cost them $2.

two will cost them $2.

twelve will cost them $4.

and a hundred and forty-four will cost $6.

What was the item they needed?

2. You have fifty bags, each with approximately one hundred balls inside. You have a weighing machine with a digital readout, with 3 places of decimals on the display, calibrated in grams, it is capable of weighing an infinite amount (but it won't have to). All of the balls in all of the bags weigh 1 gram, except in one bag in which all of the balls weigh 1.001 grams. You cannot tell by look or feel which bag has the heavier balls.

How do you determine which bag contains the heavier balls?

You can use the weighing machine only once (which means you can obtain only one reading from it before it self destructs).

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