# Posts by Damon

Total # Posts: 32,133

**math**

You are welcome. Always draw a picture.

**math**

top and bottom 2*9*12 = 216 sides 2*5*12 = 120 ends 2*5*9 = 90 sum = 426

**Geometry math**

If you tried to copy and paste diagrams here it does not work. We can not see them. for number 3 45 + 45 + x = 180 x = 90 for number 4 I think you mean equilateral and not latitude = 0 If so then 3 * x = 180 x = 60

**math**

m x -7 = -2(x^2+2x +1) -5 m x -7 = -2x^2 -4x -7 m x = -2x^2 -4x 0 = -2x^2 -(m+4) x x = 0 is always a solution

**physics question, trombone?**

at 3 meters (300 cm) you got 28.58 Hz What length gives 25 Hz? (a bit longer) subtract

**physics question**

They mean how far from straight the sum of the waves moves the string. Now if there would be just one wave you could say y = A sin (wt -kx) and the max would be A if there was one from the left and one from the right then you have y = A sin (wt - kx - phi) + B sin (Wt + kx - ...

**physics**

I get about 11.2 m/s

**Keira**

I did not answer this because I assumed you had done so. Not much of a help :(

**physics**

They give you the answer right off so I think you asked the wrong question. At terminal speed the drag force = the weight = m g = 81.5*9.81 = 800 N Too easy. They intended to ask for the terminal velocity Force = (1/2)Cd rho v^2 A = weight = m g 800 =(1/2)(.533)(1.14)(21)v^2 ...

**physics please check my answer**

The same amount of current goes through each branch say i through branch A and therefore R now in branch b we get i/2 through each, half the voltage drop at A and in branch c we get i/3 through each so 1/3 the voltage drop at A The more the paths for the current, the less the ...

**Math**

You are welcome :)

**Math**

NO!! the cos is adjacent/hypotenuse which is distance along ground / length of ladder to use tangent you need the height h^2 = 5^2 - 1.5^2 tan (angle) = h/1.5

**Math**

cos angle = 1.5/5 angle = 72.5 degrees well that is between 65 and 80

**Hey, where are your thoughts**

I am not taking this subject, you are. We are happy to help but not to simply do your work for you.

**MATH**

Factor that 10^30 out first so you have reasonable numbers

**MATH**

so I have no idea where 1.32*10^30 comes from

**MATH**

[ 3.7*10^30 +/-sqrt(13.69*10^60 -4.5*10^50) ]/2 10^60 overwhelms 10^50 [3.7*10^30 +/- 10^30 sqrt(13.69)]/2 [ 3.7 * 10^30 +/- 10^30 (3.7) ]/2 10^30 [ 1.85 +/- 1.85 ]

**MATH**

a x^2 + b x + c = 0 x = [ -b +/- sqrt(b^2-4ac) ] / 2a so it looks like a = 1 b = -3.70*10^30 c = Fr^2 = 5*10^25*2.25*10^24 = 11.25*10^49 = 1.125*10^50 now here is a quadratic solver: https://www.mathsisfun.com/quadratic-equation-solver.html

**MATH**

Now you tell me :)

**MATH**

a x^2 + b x + c = 0 x = [ -b +/- sqrt(b^2-4ac) ] / 2a so it looks like a = 1 b = -1.85*10^30 c = Fr^2 = 5*10^25*2.25*10^24 = 11.25*10^49 = 1.125*10^50 looks like a typo, M is half what it needs to be if M/2 = 1.85*10^30

**Science**

typo: A vector has both MAGNITUDE and direction.

**Science**

Velocity and acceleration are vectors. A vector has BOTH speed and direction. You can tell the speed of your car with a speedometer. HOWEVER for velocity you need BOTH a speedometer and a COMPASS. (remember that. It is a good way to remember what a vector is) The acceleration ...

**algebra 2**

as x gets huge, x^3 >> x^2 >> x so for example if y = 1x^4 + 5 x^3 well although 5 is much bigger than 1 (10^15)^4 = 10^60 5 (10^15)^3 = 5 *10^45 which is much, much smaller than 10^60 so as x goes to infinity, it is the highest power of x that counts.

**Can someone check my answer plzzz!!!**

36 x^-4 (1/2)^4 x^4 = 36/16 = 2.25 remarkably enough :)

**Trigonometry**

x^2 + 16 = 49 x^2 = 33 x = 5.7445 well sin^-1(4/7) will do that is 34.85 degrees your way tan^-1 (4/5.7445) that is also 34.85 degrees

**physics**

weight of slider = 28*9.8 = 274.4 Newtons component of weight down slope = 274.4 sin 31 = 141.3 N so if it is at constant speed the tension in the string must be 141.3 N so that is the weight of m2 m2 *9.8 = 141.3 m2 = 14.4 Kg

**Physics - please help!**

Conservation of angular momentum I1 * omega 1 = I2 * omega2 129 * 95 = 32 * new RPM by the way n RPM -> n revs/min * 1 min/60 s * 2 pi rad/rev = n* (2 pi/60) rad/s

**Math-Physics**

using Newtons, kg, meters water pressure = 1000 kg/m^3*9.8 m/s^2 * 1.5 m = 14,700 N/m^2 so total pressure = 14,700 +100,000 = 114,700 N/m^2 area = pi d^2/4 = pi 4^2/4 = 12.6 m^2 s total force down = 114,700 *12.6 = 1441400 = 1.44*10^6 sure enough Note, the air also pushes up ...

**history**

After the French and Indian war? run ! The wagons then the railroads were coming shortly and all there was realistically was to move to reservations :( There were not enough bullets to shoot all those farmers and ranchers.

**History (pls help)**

Well, the invasion of Poland by Germany in 1938 started the serious fireworks in Europe. The rest were in response. Pearl Harbor was not until Dec 7, 1941. (I was there, just in my first year of school in Honolulu. I was playing in our yard when the bombs started falling after...

**Calculus**

-10 <-1, to the left on a number line

**Calculus**

but what if x were -10 1 + 1/2^10 + 1/3^10 + 1/4^10 .....

**Physics**

moment of inertia times angular velocity or I * omega here: I = m r^2 = .45 (.36) omega = 2.5 revs/s * 2 pi radians/rev = 5 pi rad/s so angular momentum = .45*.36* 2.5 * 2*pi kg m^2/s or angular momentum = R cross P where R is radius and P is linear momentum v = .6* 2.5*2 pi P...

**physics**

He is moving, kinetic. The truck had to pull a little harder to get him moving. F = .66 m g

**Chemistry**

that has A LOT of OH-, far more than 10^-7 M .03 is much more than .0000001 a lot of OH- is a base

**Chemistry**

neutral is H+ ion concentration of 10^-7 M this has far less H+ so is a base

**maths**

8 km * (1 cm/4km) = 2 cm

**English**

I agree but see no need for a comma after Kenya unless you use two of them. 5. The territory, that became the British colony of Kenya, contained within its borders at least twenty-seven ethnic groups with different cultures.

**English**

1. yes, people who were 2. yes, b 3. yes, yet , c 4. yes, ruin 5. I do not understand why the comma is there, disagree with your answer anyway. 6. yes, stolen 7. yes no change 8. I would omit 9. I would omit 10. A and D wrong but I see no right answer.

**English**

I think it is a typo. They mean northwest of Kenya. I lost track of the numbering

**English**

1. agree 2. agree 3. stolen ... agree 4. On the other hand ... agree 5. I think I would omit the underlined ... It is redundant. 6. yes, agree, omit underlined 7. I am at a loss. I do not think any of the choices fits. However A and D are clearly wrong.

**physics please help!!**

QE = 9*10^9 *3*10^-9 *3*10^-9/.1^2 = 81*10^-9/10^-2 = 81*10^-7 = 8.1*10^-6 N

**Math**

sorry, I missed, y = -x^3

**Math**

y = x^x ?? well the exponent is x but the base is not a constant. I would say it does not fit the definition form of y = a * b^x where a and b are constants

**Science**

All of those vector things change in either magnitude or direction. The only scalar is mass, so you are right. You could argue about centripetal acceleration because if the radius is constant the centripetal acceleration has constant MAGNITUDE, but the direction is not ...

**Physics**

This is a bunch of articles in the latest MIT Physics department magazine (Physics at MIT 2017 Annual) about current research. It is about quarks and gluons. [ The Secret Life of Quarks, Lattice Quantum Chromodynamics, Jetting through the Quark Soup ]. I am not going to try to...

**Physics**

remember integral a t dt from t = 0 to t = T = (1/2)a T^2 That is where the 1/2 comes from, area under straight line (triangle)

**Physics**

You mean .5 * 10^4 ? I am saying that current is proportional to time during the rise (and fall) It goes from 0 to 10^4 in 10^-5 seconds the area under that straight line is .5 * 10^4 *10^-5 which is the charge passed in that time Therefore my answers should be half yours ...

**lightning bolt**

we need to find the total charge passed during the rise and fall during rise i = {10^4amps /[10^-5 s]}t area under that line (the triangle) is in coulombs Q = .5*10^4*10^-5 = .05 Coulombs during fall Q = .5*10^4 *10^-4 = .5 Coulombs peak power = volts * peak amps 10^7 * 10^4...

**Physics**

1 Coulomb charges 1 km apart E = k Q/r^2 r = 10^3 E = 9*10^9 /10^6 = 9000 EQ = 9000 N

**Physics**

I can see it and am looking I am wondering if the voltage and current should be linear in time upward during the rise and then linear during fall. In the last one not only are you neutral charge overall but your individual parts tend to be neutral atom by atom. You do not have...

**Physics**

Hard for me to tell.

**Hey, you do some**

I already took the subject. It is your turn. We are here to help, not to do all your work for you. A couple of your questions are interesting but most are standard.

**Physics**

we need to find the total charge passed during the rise and fall during rise i = {10^4amps /[10^-5 s]}t area under that line (the triangle) is in coulombs Q = .5*10^4*10^-5 = .05 Coulombs during fall Q = .5*10^4 *10^-4 = .5 Coulombs peak power = volts * peak amps 10^7 * 10^4...

**science**

https://en.wikipedia.org/wiki/Subduction

**Physics**

not immediately alpha = ang acceleration = d omega/dt F = m Ac = m v^2/R = m omega^2 R where omega = angular velocity and v = tangential velocity (omega*R) and m is any particle on the disk at radius R v is velocity not acceleration however over any finite time, acceleration ...

**Math**

T > -15

**Physics**

Ke = (1/2) m v^2 so (1/2) (90) v^2 = 2205

**Science**

https://water.usgs.gov/edu/vapor-pressure.html at around room temperature vapor pressure methanol = about 13 k Pa vapor pressure of water = about 2 k Pa in other words the alcohol is trying much harder to get out.

**Chemistry**

diameter = .025 cm area = pi D^2/4= 4.91 * 10^-4 cm^2 so 4.91*10^-4 * L * 8.96 = 22 L = 5002 cm or L = 50 meters

**electrical trade theory**

usually carbon/graphite like the lead in a pencil. There are other ways, even liquid metal, but that is the usual material.

**electrical trade theory N2**

just answered that, carbon, graphite like a pencil lead.

**Math (Word Problems)**

(9/6) * (3/4) = (3/2)(3/4) = 9/8 = 8/8 + 1/8 = 1 1/8

**History**

I guess I have to say it. You are asking a person whose father was killed by a Japanese shell on the bridge of the Cruiser San Francisco between Guadalcanal and Savo Islands, what later was named "Iron Bottom Sound" in November of 1942.

**History**

No comment.

**Chemistry**

ice --> serious hydrogen bonds :)

**physics please help**

node at closed end, max at the open end. Draw the picture. first boom at 1/4 of wavelength = length of tube L say the speed of sound is c c = wavelength /period = wavelength* f now we are told that 1/4 wavelength is L c = 4 L*200 = 800 L so the next time we have a node at the ...

**help**

b/g = 2/3 or b = (2/3)g b+g=50 2g/3 + 3g/3 = 50 5g/3 = 50 g = 150/5

**physics**

work in = increase in potential energy = (1/2) k x^2 that becomes kinetic energy of the arrow = (1/2) m v^2

**physics**

.3 * 2.2 = .3 u + .8 v and if elastic 1/2(.3) (2.2)^2=1/2(.3)u^2+1/2(.8)v^2 and if inelastic (glued together) u = v .3*2.2 = 1.1 u Ke = (1/2)(1.1)u^2

**History**

Remember the Civil War ended shortly before this amendment went into effect. If you are going to write an essay about it describe what the particular reason was and who was behind it and whom it was to protect immediately.

**math**

11 km * 1 hour/10 km = 1.1 hour

**physics**

East momentum before = 820 c North momentum before = 2000 t those will be the same after mass after = 2820 East after = 2820 * 16 sin 24 North after= 2820 * 16 cos 24 so 820 c = 2820 * sin 24 and 2000 t = 2820 * cos 24

**Math**

well, I do not see your diagram but suspect you mean the two triangles under the latter which share the angle at the ladder/ground point and a right angle at the base of the fence and the wall. Therefore angle-angle -angle ---> similar .5/2 = 2/h h = 4/.5 = 8 meters high

**Math**

The thing is that it asks for length of the tree, not height. Perhaps it is just a typo and they want 41 feet total height.

**Math**

The tree is indeed an incorrect list of answers

**Math**

62-12 is NOT 74, DRAW A PICTURE !!!

**Math**

C) descend 84 Feet*** Yes

**Math**

At 6:00 A.M. the temperature was 33Â°F. By noon the temperature had increased by 10Â°F and by 3:00 P.M. it had increased another 12Â°F. If at 10:00 P.M. the temperature had decreased by 15Â°F, how much does the temperature need to rise ...

**Math**

-1500 + 5000 - 1500 = 5000-3000 = 2000 so yes C

**Math help me please**

I agree with bobpursley. None are correct.

**Analytical chemistry**

2 K2Cr2O7 + 3 FeSO4 + 14 H2SO4 = 2 K2SO4 + 2 Cr2(SO4)3 + 3 Fe(SO4)3 + 14 H2O for every 2 mols of K2Cr2O7 you need 3 mols of FeSO4 You have .01*60*10^-3 mols of K2Cr2O7 so you need .01(3/2)*60*10^-3 mols of Fe(SO4)3 in 20*10^-3 liters .01(1.5)60/20 = .045 mols/liter

**Algebra**

hypotenuse

**math(PLEase help me check.)**

1) C=md+t The cost C, of a business trip is represented by the equation above, where m is a constant, d is the number of days of the complete trip, and t is the cost of transportation, which doesn't change. If the business trip was increased by 5 days, how much more did ...

**Chemistry**

Well, 1. describes a solid I think. 3. is a "plasma" of ionized particles 4. sounds like water to me

**typo**

at distance r from ellipse center semi height of ellipse is 2r

**math**

length of semi ellipse on one end = 2r+rsqrt3 =a at distance r from ellipse center semi height of ellipse is r find height of ellipse at center r^2/[(2+sqrt3)^2r^2] + 4r^2/b^2 = 1 then area = pi a b

**Geography**

A lot ! http://www.orangesmile.com/common/img_country_maps/india-map-0.jpg expand this by clicking on + button so you do not miss details like Sikkim and Bhutan

**math**

top and bottom 2*.5*.35 two sides 2*.5*.1 two ends 2*.35*.1 add them, then multiply by 60

**Math**

start here: http://davidmlane.com/hyperstat/z_table.html

**Math**

x + (5+y) http://www.ducksters.com/kidsmath/mathematical_laws.php

**PHYSICS**

capacitance = charge per unit voltage In other words if you connect this capacitor to a one volt battery it will store 5 *10^-6 coulombs

**Now wait a minute**

I showed you how do do a very similar problem. Bob Pursley showed you how to do this one. We are here to help you learn, not do the problems for you. Please show your attempt in detail. https://www.jiskha.com/display.cgi?id=1518974637#1518974637.1518980819

**calculus**

http://www.wolframalpha.com/input/?i=integral+2dt%2F(t%5E2%2B3+t%2B1) looks more like your first answer

**math**

2 A = h b + h B h B = 2 A - h b B = (2 A - h b)/h or = 2(A/h) - b

**physics**

v^2/R where v = 2 pi R /50 = 60 so R = 3000/(2 pi) = 1500/pi Ac = 60^2 (pi/1500)

**Maths**

I am sure they made that longitude difference 180 degrees on purpose so we would not really have to use spherical trig. I know the earth is squished a little but we who plod around on the surface of the ocean do not worry about it much :)

**Maths**

By the way this is why a ship between England and New York is likely to go way up near Newfoundland and Nova Scotia (in some cases braving icebergs).

**Maths**

Well, I will do this in nautical miles since that is my thing. You have to correct if you are using feet or land miles or meters or kilometers. Now around the earth at the equator is360 degrees which is 360 * 60 = 21600 nautical miles but due to a brilliant decree by Napoleon ...

**Physics**

at the start air pressure in bottom of tube = 76 + 15 = 91 cm Hg when horizontal the pressure will be 76+0 = 76 cm P2 V2 = P1 V1 since n and R and T are the same 20 * 91/76 = 23.9 when upside down Pair = 76 - 15 = 61 cm Hg 20 * 91/61 = 29.8