Thursday

July 24, 2014

July 24, 2014

Total # Posts: 17,502

**trig**

cos 35 = h/15

**Physics**

Yes, if the friction was less than the force required to accelerate the upper block, it would accelerate more slowly than the bottom one. In other words slip :)

**Physics**

You are welcome :)

**Physics**

F = - k x = -130 (.1) = -13 N if they do not slip m = 6.25 kg a = 13/6.25 = 2.08 m/s^2 force required to accelerate small block = 1.25 *2.08 = 2.6 N do we have that much? weight = m g = 1.25 * 9.81 so max friction = .3*1.25*9.81 = 3.68 N so no slip :)

**Math? Check Answers Please!!**

You are welcome :)

**Math? Check Answers Please!!**

1) yes 2)4^4 * 4^6 = 4^(4+6) = 4^10 3)4^(4+44) = 4^48 4) 3^(4-4) = 3^0 = 1 note ANYTHING^0 = 1 5) 3^-3 = 1/3^3 = 1/27 yes

**Physics**

2.05 2.04

**Physics**

initial momentum forward = (69.5+.47)(2.15) = 150.4 so 150.4 = 69.5 v + .470*16 in second part v ball = 2.15 + 16 = 18.15 m/s 150.4 = 69.5 v + .470*18.15

**Science**

Thanks for catching that !!!

**Science**

You have to add heat so endothermic 129 J per 2 mol 1 mol = 23 + 1 + 12 + 48 = 84 grams 2 mol = 168 grams we only have 18.5 grams so (18.5/168)129 = 14.2 Joules

**Physics**

change in x momentum = 2 * mass * x velocity = 2 * .275 * 4.5 sin 35 force on ball by wall = change in momentum /time = change in momentum/.008 wall on ball is -x so ball on wall is + x direction

**Math Homework: Check Answers**

You are welcome.

**Math Homework: Check Answers**

1. Suppose you earned 8t - 3 dollars on Monday and 6t + 5 dollars on Tuesday. What were you total earnings? Simplify your answer. A) 2t + 2 B) 2t - 8 C) 14t + 2 D) 14t - 8 Answer: A ------------------------------- 8t+6t= 14 t !!! so 14 t + 2 -------------------------------- 2....

**physics**

r w^2 = Ac = 6*10^5*9.81 w^2 = 58.9 * 10^5 /.02 = 29.4 *10^7 = 2.94 * 10^8 w = 1.72 * 10^4 = 17,200 radians/sec

**probability**

-->1 2 3 4 5 6 1 ----- * 2 ----* 3 --* 4 * 5 6 36 possible outcomes get 5 from four of them so p = 4/36 = 1/9 (1/9)180 = 20 times

**geometry**

Area of base = (1/2)(.25)(.25 sin 60) = .0271 m^2 .0271 * h = 7.5 h = 277

**physical science**

You are welcome :)

**physical science**

see below I got 94 %

**physical science**

100( power out ) /power in 100*3760/4000 = 94 %

**Geometry**

between 0 and 1 hour Ann went 3 miles per hour between 1 hour and 4 hours, Ann went 2 miles (5-3) so 2 miles /3 hours = .67 mph between 4 hours and 7 hours Ann went zero miles (5-5) so zero miles/hour (lunch break?) between 7 ours and 10 hours (3 hours) Ann went 5 miles (10-5)...

**ALGEBRA! URGENT. Check Answers!**

You are welcome.

**ALGEBRA! URGENT. Check Answers!**

yes

**ALGEBRA! URGENT. Check Answers!**

in #3 + 5x - 7x = NEGATIVE 2 x #4 negative 7

**math**

bottom = pi r^2 top = pi r^2 side = 2 pi r h

**Physics, am i right?**

If you have a whole bunch of resistors in parallel you can do 1/R = 1/R1+ 1/R2 + 1/R3 + 1/R4 .... Since the current has a choice which resistor to go through, you are adding CONDUCTIVITIES (inverse of resistance) C = C1+C2+C3 ... then in the end R = 1/C or you can do them cons...

**Physics, am i right?**

You are very welcome :)

**Physics, am i right?**

R = 10*20 /30 = 20/3 i = 9 /(20/3) = 27/20 = 1.35 Amps Yes !

**calculus**

(14x + 4)cos(7x^2 + 4x)dx,substitution u = 7x^2 + 4x. u = 7 x^2 + 4 x du = 14 x dx + 4 dx = (14x+4)dx so we have integral of cos u du which is - sin u + c - sin (7x^2+4x) + c

**calculus**

u = x3 + 5x2 + 18 then du = 3 x^2 dx + 10 x dx so in fact we have u du integrate u^2/2 + c so the hard part is squaring .5 (x^3 + 5 x^2 + 18)^2 + c

**histoy**

Life tenure is democratic NO ! Important people have special rights in a democracy NO People vote in a democracy YES Some slaves freed? What about the rest ? Not the question anyway. Some democracies had slaves (Athens, USA). They may not be proud of it.

**Physics**

R = 10*30 / (40) = 7.5 45/7.5 = 6 Amps

**Physics**

10 in PARALLEL with 30 1/R = 1/R1 + 1/R2 or R = R1 R2 /(R1+R2)

**Physics**

NO!!!

**algebra**

P(mean of A) if mean P(A) = .6 If we have six Apples and four Oranges in a box then P(A) = .6 when we draw one thing at random. If we have a whole bunch of boxes and on the average there are six apples in each then P(A) = .6 BUT The probability that we will draw that mean on a...

**algebra/Can you see if I am right**

Probability of the first one being a king is 4/52 probability of the first one being a face card = 12/52 the probability of the second one being a face card if the first was a king is 11/51 so if you mean probability of choosing a king, then a face card it is 4/52 * 11/51

**physics**

I have no idea.

**math**

add x to both sides x + y = a add -y to both sides x = a - y

**general chemistry**

Number of mols/liter

**math**

Instead of posting it again, read what you posted. It is incomplete. What is K and what does it have to do with the problem. We do not know the ratio of speeds for walking or taking the bus.

**Physics**

V = i R 20 = i (10) i = 2 amps so yes, b

**algebra/check my answer**

find probability that NONE are heads (1/2)^3 = 1/8 so we want 1 - 1/8 = 7/8 agree with you

**Calculus**

y^2 + 4 y = -8 x + 12 y^2 + 4 y + 4 = -8 x + 16 (y+2)^2 = -8 (x-2) vertex at (2,-2) opens left etc

**algebra**

You are welcome.

**algebra**

out of 13 men, 12 are bald? 12/13

**7th grade Math (polynomials)**

maybe: -8.5 x^3 + 0 x^2 + 1.1 x + 0

**algebra**

(-3)^2 -4(-3) + 3 9 + 12 + 3 24

**math**

7! = 7*6*5*4*3*2*1 = 5,040 agree

**maths**

10 *(10^x)^2 - 7 (10^x) = 26 let z = 10^x 10 z^2 - 7 z -26 = 0 ( z - 2)( 10 z + 13) = 0 10^x = 2 or 10^x = -1.3 if you log is base 10 log 10^x = x = log 2 but if x = log a then log a = log 2 so a = 2 similarly log 10^x = x = log (-1.3) but not allowed :)

**science (check!)**

agree, If the predator is not to run out of food, he needs a lot of prey per predator.

**Math, grade 10**

anyway a^2 + (17-a)^2 = 185 a^2 + 289 - 34 a + a^2 = 185 2 a^2 - 34 a + 104 = 0 a^2 -17 a + 52 = 0 (a- 13)(a-4) = 0 a = 4 or 13 so they are 4 and 13 and my initial thought was wrong

**Math, grade 10**

not real numbers 17^2 = 289 which is greater than 185

**please help**

Well, I had a dislocated shoulder once.

**Algebra II**

By the way, there are an infinite number of solutions. eg 3 cos (4x - 7 pi/2)+4 or - 3 cos(4x -pi/2) + 4 etc

**Algebra II**

You are welcome :)

**Algebra II**

also in your explanation explain that the cosine curve is 90 degrees or pi/2 radians behind the sine curve if you graph y = sin theta and y = cos theta versus theta

**Algebra II**

trig identity: sin theta = cos (pi/2-theta) so y = 3 sin (4x-pi) + 4 but from above trig identity y = 3 cos [ pi/2 - (4x-pi) ] + 4 or y = 3 cos (-4x + 3 pi/2) + 4 but cos (- theta) = cos theta so y = 3 cos (4x-3 pi/2) + 4

**PRECALC QUESTION**

6 x +0 y = -24 so x = -4 -4 x + .5 y = 19 so y = 6 -6 + 0 = -6 true (-2)(-2) + (1)(1) = 5 true

**3D Shapes & Scale**

I mean big surface area for its weight

**3D Shapes & Scale**

by the way the ant is not only immensely strong for its weight but that A - k L^2 ratio means it has a big surface area for its length. Therefore it's terminal velocity is much lower than yours.

**3D Shapes & Scale**

1) Archimedes holds you up in the ocean. Water is about 800 times as dense as air. In fact it is about the density of most animals, including people and whales. Therefore when you are in the water you need to exert very little force to hold yourself up. Similarly a whale is ab...

**3D Shapes & Scale**

L2 = 10^3 L1 Area 2 = (10^3)^2 = 10^6 Area 1 volume 2 = (10^3)^3 = 10^9 volume 1

**Ed Tech**

By the way, if you include analog as well as digital computers, I was using tube varieties as late as 1964 for simulation of ship motions and vibration measurement and analysis.

**Ed Tech**

Code breaking was one use but the use I am familiar with is generation of tables solving spherical triangles for navigation by sextant. Using a companion volume " Nautical Almanac" you looked up where a ray from the sun or moon or star intercepted the surface of eart...

**Earth Science Regents!!!**

Laruen: Google "celestial navigation".

**need help1 what function to use? math**

That is correct

**ALGEBRA**

sorry, 4200-x

**ALGEBRA**

4300 - x

**Math**

I assume you mean with integer lengths L + w = 10 L = 5, w = 5 as you said L = 6, w = 4 L = 7, w = 3 L = 8, w = 2 L = 9, w = 1 the ones with w>L do not count because they are indistinguishable from the ones we have now. , So, 5.

**chamastry**

a mL IS a cm^3 p v = n R T P1 V1/T1 = P2 V2/T2 if n and R constant I guess you want the pressure to be the same? then V1/T1 = V2/T2 so T2 = (V2/V1)T1 T2 = (40/500)400 T2 = 32 k very cold

**Physics**

Since you do not specify, I will assume 60 degrees from horizontal tan 60 = mg/(m v^2/r) v^2/r = g/tan 60 v^2 = g r/tan 60 v = sqrt(981/tan 60) v = 23.8 m/s

**math trig**

cos 38 = h/3.8

**math**

maybe you mean 3^(2x) - 3^(x+2) + 8 = 0 let z = 3^x z^2 - 9 z + 8 = 0 (z-8)(z-1) = 0 z = 1 or z = 8 x = 0 or x = 2

**English III**

LOL - Who led the troops who arrested John Brown ?

**English III**

The tone is certainly firm. Of course the effect is wishy-washy in that if you are a slave you are only to be freed if you are in an area in rebellion. If you happen to be a slave in a state that did not rebel, well you better wait for a constitutional amendment.

**English III**

I agree with you.

**algebra1a**

first equation is 2 x + 6 y = -4 second equation is 2 x + 6 y = -4 the same, no intersecting lines, no solution

**Algebra**

remaining = x walked = 3 x 3 x + x = 1164 4 x = 1164 x = 291

**History: Check My Answers PLEASE**

I may be anticipating the next chapter :)

**History: Check My Answers PLEASE**

Which are accurate descriptions of how the Christian church influenced daily life in the Middle Ages? Choose all answers that are correct. A.encouraged people to rebel against unjust feudal lords B. oversaw the writing of wills and contracts C. made and enforced the rules and ...

**History: Check My Answers PLEASE**

A. Most were weakened and eventually overthrown by feudal lords. B. Their power was held in check by parliamentary bodies elected by freemen. C. They were required to ask the pope's permission before they could wage war. D. Many extended their control and left larger kingd...

**Algebra 2**

y = 7 + 5/(x-6) would work

**algebra**

r = .05/12 = .004167 interest per payment 1+r = 1.004167 n = 12*40 = 480 number of payments amount = 150 [ 1.004167^480 -1 ]/.004167 = 150 [7.3584 - 1 ]/.004167 = $ 228,884.71

**Algebra 1**

Perhaps you mean ???? [ 6w^2 + 11w - 7 ] / [ 6w - 3 ] (2w-1)(3w+7) / [3(2w-1)] (3w+7)/3

**Precalculus**

y = 8/x x^2 + 4 (64/x^2) = 68 x^4 - 68 x^2 + 256 = 0 let z = x^2 z^2 -68 x + 256 = 0 (z-64)(z-4) = 0 z = 64 or 4 so x = 2 or -2 or 8 or -8 if x = 2, y = 4 if x = -2, y = -4 if x = 8, y = 1 if x = -8, y = -1

**Math**

die a-> 1 2 3 4 5 6 die b 1 2 3 4 5 6 36 boxes label them for the sum of number above and to the left eg 2 3 4 5 ....7 3 4 5 7 ....8 4 5 ........9 etc Now for example 6 of the boxes contains a sum less than 5 that means 30/36 are greater than five of course 30/36 = 5/6

**math**

a = apples b = bananas = 2a a + 2 a = 45 3 a = 45 a = 15 b = 2 a = 30

**Precalculus**

but I have -16 x^2 -200 x = 600 so 16 x^2 + 200 x + 600 = 0 x = -7.5 or -5 check -7.5 16(7.5)^2 -200(7.5) +600 900 - 1600 + 600 zero, it worked for me

**Algebra**

amplitude is 2 when theta = pi/2 we have sin 2 pi so period is pi/2 A.

**math**

but if you really mean what you said,(which I doubt) divide by (1/4) that is 4 times or 500%

**math**

100 * (1/4) = 25%

**PHYSICS**

8 sin 30 + 8 sin (180-120) 4 + 8 (.866) = 4+6.93 = 11 N In other words none of the above I bet you mean 30 and 150 with x axis in which case C

**Physical sciences**

-50* 1.6*10^-19 = -80*10^-19 = -8*10^-18 C

**maaattthhhh**

http://www.mathportal.org/calculators/statistics-calculator/descriptive-statistics-calculator.php mean = 23.375 median = 22 mode = 26 so the last choice you listed 37 - 25 = 12 37 is a long way from the others.

**physics**

You are welcome.

**physics**

tan theta = 3/100 so sin theta = .0299865 -500 (.0299865) = -14.99 they defined y as up so it is negative

**physics**

LOL, the way MathMate did it is a lot easier :)

**physics**

The total energy at the top of the trajectory is the same as was stored in the spring (1/2)kx^2 Total energy at top where v = 0 = (1/2) u^2 + m g h we can find u, horizontal velocity easily u = 24.7 m/2.72 s = 9.08 m/s but Vi, initial speed up is easy too tan 55.8 = Vi/u Vi = ...

**Algebra**

a^(-1.5) ?

**physics**

say the mass is 1 and the length is 1 if the length were 0.98, the volume would be .98^3 = .941 then if the mass were 1.03 density = mass/volume = 1.03/.941 = 1.094 or 9.4 percent greater

**Physics**

Volts is not power Amps is not power WATTS is power (volts times amps) watt hours is energy, not power so it has to be 10 kW which is very high, let me see 220 Volts * 50 amps = 11,000 Watts = 11 kW well this is a pretty hefty oven. I could not run two of them in my house :)

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