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I'm not sure how to do these problems..Can u plz explain and if ur a really nice person, plz answer them...if it's not too much to ask.

1) Two pipes are connected to the same tank. When working together, they can fill the tank in 8 hrs. The larger pipe, working alone, can fill the tank in 12 hrs less time tha the smaller one. How long would the smaller one take, working alone, to fill the tank?

2)Solve for the indicated letter: R=xD^2+jDf for D
D=?

3)If an object is thrown downward with an initial velocity of Vo (the o is a zero), then the distance it travels is given by s=4.9t^2+Vot. An object is thrown downward from an airplane 300m from the ground, with an intial velovity of 5m/sec. How long does it take for the object to reach the ground? (simplify ur answer. Type an integer or a decimal. Round to the nearest tenth.)

4) A record for free-fall to the ground without a parachute is 175ft. How long did the fall take? Use the formila s=16t^2.

2007-07-21 11:47:39 · 7 answers · asked by AnimalsFan 3 in Science & Mathematics Mathematics

7 answers

3)

s=4.9t^2+Vot

Substitute given data to this equation.

300 = 4.9 * t^2 + 5 * t

Solve this quadratic equation to get the answer.

Note: The initial velocity is added to velocity of free fall (not subtracted!) because of the same direction.

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

(The object falls to the ground after 35,92 seconds.)
-

2007-07-21 12:00:48 · answer #1 · answered by oregfiu 7 · 1 1

ok, i'll help you

let t be the time it takes the smaller pipe to fill the whole tank. The larger tank fills the tank 12 hrs less than the time it takes the smaller pipe to fill the tank, so, t - 12 is the time for the larger tank

now find the rates for each pipe

In 1 hr, the smaller pipe can fill 1/t of the tank
In 1 hr, the larger pipe can fill 1/ (t - 12) of the take

rate of the smaller pipe: 1/t tank/hr
rate of the larger pipe: t/(t - 12) tank/hr

Now that the two pipes fill the tank two together, it takes only 8 hrs.

so how much of the tank the smaller pipe can fill in 8hrs plus how much of the tank the larger piple can fill in 8hrs equals one whole tank

tank (smaller pipe) = 1/t * 8 = 8/t
tank (larger pipe) = 1/(t - 12) * 8 = 8/(t-12)

8/t + 8/(t-12) = 1

8(t-12) / (t^2 - 12t) + 8t / (t^2 - 12t) = 1

8(t-12) + 8t = t^2 - 12t
8t - 96 + 8t = t^2 - 12t
0 = t^2 - 28t + 96

use quadratic formula and you'll get t = 24

the smaller pipe can fill the tank in 24 hrs
the larger pipe can fill the tank in 12 hrs

2) use quadratic formula

3) s = 4.9t^2 + Vt + si

0 = 4.9t^2 + (-5)t + 300

Note: the reason i put -5 fot Vo instead of +5 because the intial speed of the object intial was downward.

0 = 4.9t^2 - 5t + 300

use quadratic formula and you'll get t = 7.33s


4) just plug in 175 for s

175 = 16t^2
t = sqrt(175/16)
t = 3.31s

2007-07-21 12:19:37 · answer #2 · answered by      7 · 1 0

A record for free-fall to the ground without a parachute is 175ft. How long did the fall take? Use the formila s=16t^

S=vot +1/2at^2<<<< S=1/2at^2
175=1/2(32 ft/sec^2)t^2
175=16ft/sec^2* t^2
175/16= t^2
t= (sq root of 175/16) <<<<<<<<<<<

2007-07-29 11:47:31 · answer #3 · answered by Anonymous · 0 0

the area between 2 factors is predicated on the pythagorean theorem. You calculate the entire upward thrust (distinction between the y coordinates) and the run (distinction between the x coordinates), and then build a suited triangle such that the hypotenuse is the line between the two factors. -14 - (-2) = -12 (your "upward thrust") 12 - 9 = 3 (your "run") via pyth thm, (-12)^2 + 3^2 = d^2, the place d is the area between the two factors. (-12)^2 + 3^2 = d^2 a hundred and forty four + 9 = d^2 153 = d^2 d = sqrt(153), or the sq. root of 153 = approximately 12.369. wish it helps.

2016-10-09 05:20:37 · answer #4 · answered by ? 4 · 0 0

Don't despair. I'm going to take a short nap and be back in 1 hour to edit my answer and see what I can chip in.


....Ok, I'm Back.... I slept for 2 hours. A lot of fine people gave you a hand with this. Good luck!!

2007-07-21 11:51:38 · answer #5 · answered by Frank V 3 · 0 1

For #2

first, get rid of the exponent - r=xdd+jdf

then divide both sides by 3d - you're left with

r/3d=x+jf

then multiply by 1/r - you're left with

3d=x+jf/r

then multiply both sides by 3 - you're left with

d=x+jf/3r

This is the only one I remember how to do... sorry I can't help with the others

2007-07-21 12:10:01 · answer #6 · answered by bookgirlocmd 3 · 1 1

i would love to help but am just in algebra 1....barely

2007-07-21 11:50:24 · answer #7 · answered by Anonymous · 0 1

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