Wednesday

July 23, 2014

July 23, 2014

Total # Posts: 17,491

**algebra**

Hey, I did one, your turn :)

**math**

3^5 + ***** 3^4 (bx) + ****** 3^3 (bx)^2 + ........ now get binomial coefficients for fifth power from Pascal's triangle or formula 1 5 10 10 5 1 so 3^5 + 5*3^4 b x + 10 * 3^3 b^2 x^2 243 + 405 b x + 270 b^2 x^2 ......

**calculus**

Nor do I

**calculus typo**

y = x^(2/3) at x = 1 which is b y = 1^(2/3) = 1 at x = 0 which is a y = 0^0 = 0 y(1) - y(0) = 1 - 0 = 1 b - a = 1 - 0 = 1 so 1/1 = 1 so according to the mean value theorem somewhere between x = 0 and x = 1 the derivative = 1 dy/dx = (2/3) x^-1/3 = (2/3)/x^(1/3) when is that eq...

**calculus**

y = x^(2/3) at x = 1 which is b y = 1^(2/3) = 1 at x = 0 which is a y = 1^0 = 1 y(1) - y(0) = 1 - 0 = 1 b - a = 1 - 0 = 1 so 1/1 = 1 so according to the mean value theorem somewhere between x = 0 and x = 1 the derivative = 1 dy/dx = (2/3) x^-1/3 = (2/3)/x^(1/3) when is that eq...

**Calculus**

y = 2 (x+5)^3 + 7 to make this really easy you can say z = x+5 then dz/dx = 1 y = 2 z^3 + 7 dy/dz = 6 z^2 d^2y/dz^2 = 12 z so dy/dx = dy/dz * dz/dx = 6(x^2+10x+25) when is that zero ? (x+5)(x+5) = 0 x = -5 twice what is d/dx (dy/dx)? 6 ( 2 x + 10) when x = -5 2(-5)+10 = 0 so t...

**physics typo**

physics - Damon, Tuesday, July 22, 2014 at 4:37am Newton #1 - If there is no NET force, momentum is constant. Here speed is steady (I assume in a straight course) and mass is constant so net force is zero. Newton #3 - Action is equal and opposite to reaction. So Propulsion for...

**physics**

Newton #1 - If there is no NET force, momentum is constant. Here speed is steady (I assume in a straight course) and mass is constant so net force is zero. Newton #2 - Action is equal and opposite to reaction. So Propulsion force forward must be equal and opposite to resistanc...

**Math 221*revised***

You can enter that as 5' 2" in the web site I gave you: http://www.mayoclinic.org/bmi-calculator/itt-20084938

**Math 221**

http://www.mayoclinic.org/bmi-calculator/itt-20084938 You need male or female and birth date.

**Physics**

vertical problem first h = Hi + Vi t - 4.9 t^2 0 = 80 + 300 (sin 30) t - 4.9 t^2 solve quadratic for t. Use positive t, the other root was on the way up underground. then Horizontal problem at constant u = 300 cos 30 d = u * t

**Physics**

What might happen if you increased the volume?

**Physics**

http://www.schoolphysics.co.uk/age16-19/Thermal%20physics/Gas%20laws/text/Adiabatic_change_equation/index.html Note example problem with adiabatic expansion to twice volume.

**Physics**

http://www.schoolphysics.co.uk/age16-19/Thermal%20physics/Gas%20laws/text/Adiabatic_change_equation/index.html Note example problem with adiabatic expansion to twice volume.

**physics**

horizontal pull = 20 cos 60 = 10 N vertical pull up = 20 sin 60 = 17.3 N normal force = m g - 17.3 friction force = .4 (9.81 m - 17.3) = 3.92 m - 6.92 so 3.92 m - 6.92 = 10

**math**

Carrie = 1 case / 5 hours = .2 case/hr James = 1 case/3 hours = .333 case/hr together they do .533 case/hr so .2 * 1 hr + .533 * x hr = 1 case .533 x = .8 x = 1.5 hours more

**physics**

It is a loop of wire operating in a changing magnetic field, changing because sometimes the B flux is through the plane of the coil and sometimes it is parallel to the plane of the coil and no B goes through the coil. B = 1.8 Tesla B through coil = 1.8 sin 2 pi f t f = 60 so 2...

**Calc**

You are welcome.

**Calc**

You forgot dx :) Now I just did one of these a couple of questions down. This time use rectangles with the left hand height. Evaluate left hand heights of function at 12 13 14 15 spacing is one so multiply each left hand height by 1 and add

**Science**

ni sin i = nr sin r 1 sin 50 = nr sin 40 nr = sin 50 / sin 40

**Calc**

I assume you mean v(t) = t^2 + 2 I am not going to do the four trapezoids for you but I will do the integral so you know if you have done the area right. s(t) = (1/3) t^3 + 2 t + c when t = 0, let s = 0 so let c = 0 (we could chose any old starting s and resulting constant c b...

**Math**

I bet "original" is "wholesale" :) multiply original by 1.20 then by 0.75 1.2*3/4 = .9 so 145 * .9 = $130.50

**Calc**

Oh and by the way when x = 0 we have 0/1

**Calc**

df/dx = - x e^-x + e^-x = 0 for max or min within interval BUT you did not say the interval in general e^-x = x e^x 1 = x is one place where the slope is zero is the second derivative + or - ? d^2f/dx^2 = -x(-e^-x) -e^-x - e^-x = xe^-x -2 e^-x) = (1/e^x)(x-2) when x = 1 = (1/e...

**science**

force * time = change of momentum a) force = 49 * (6-0) / 3 = 98 N b) force acts on the average over one hundred meters c) work = force * distance = 98 * 100 = 9800 Joules interesting, lets see how much kinetic energy we have (1/2) m v^2 = .5 * 49 * 36 = 882 Joules s we are no...

**Math**

always multiply by one (top equal to bottom) so the units come out with the unwanted ones canceling 23 cm * (1 meter / 100 cm) note cm cancels top and bottom, left with meters besides we all know 23 cm = 0.23 meters :) b) NO !! 1000 mm / one meter = one 5 m * (1000 mm / 1 m) =...

**math geometry**

lengths scale with scale ratio areas scale with scale ratio squared volumes scale with scale ratio cubed so scale ratio = 30/24 = 1.25 area ratio = 1.25^2 = 1.5625 volume ratio = 1.125^3 = 1.953125 so a) 1/1.25 = .8 = 8/10 = 4/5 b) 1/1.5625 = .64 = 16/25 c) 1/1.953125 = .512 =...

**physics**

I bet they both hit the ground at the same time, whenever that is.

**where asre the = signs?Math**

I do not understand this.

**Alegbra**

subtract negative 40 from positive 119 or simply add 119 and 40 +119 - (-40) simplified = 119 + 40 = 159

**science**

Open the box and take the hard drive, or simply take the computer.

**American literature**

"...... community.(256)..... " What is your reference number 256 ?

**calculus**

Profit = Revenue - Cost P = -q^3 + 60 q^2 +(-1200+551)q - 760 dp/dq = -3 q^2 +120q - 649 zero for max or min q^2 - 40 q + 216.333... = 0 q = [ 40 +/-sqrt (1600-865)]/2 q = [40+/-27.1)/2 q = 34 or 6.5 to find out if max or min, take next derivative d^2p/dq^2 = -6q +120 at q = 3...

**physics 2**

I do not understand. Mass of object increases above rest mass as speed of light is approached. .08 times original mass????

**physics**

energy to water per second = 1.86*10^8 Joules Kg water per second heated = m 1.86*10^8 = 4184 * m * 2

**US Government**

The answer is in the link Ms. Sue gave you.

**Alegbra**

It is very difficult to fit a line to one point.

**Alegbra**

both sides are 0 at (6,-8) then y goes down 5 times as fast as x goes up check: from that point go right 1 and down 5 (7, -13) is that on the line? -13 + 8 = ???? -5 (7-6) -5 = -5(1) sure enough

**engr240**

I have no idea. Is this part of an equation? Should it be equal to zero or something?

**Alegbra**

y = m x + b 7 = 0 + b b = 7 so y = -6 x + 7 where does that hit x axis ? 0 = -6 x + 7 x = 7/6 so (7/6 , 0) draw line through (7/6 , 0) and (0 , 7)

**Geometry**

2 pi r = 2 pi (2x) = 4 pi x

**Physics mit 2.01x**

No (former MIT professor), I do not do MITx problems in Course 8 or Course 2. You are on your own. The 8.01x crowd swamped this board the last time around.

**science**

pi r^2 h pi 1*1*12 = 12 pi cm^3 or cc = 37.7 cubic centimeters

**physics**

a) Huh? at x = 0 and t = 0 , y = 0 so the phase constant is 0 b) at x = .0229 m and t = .197 .745(.0229) - 42.9(.197) = -8.434 radians = -482 degrees which is -360 - 123 degrees

**physics**

well, first do the vertical problem, the ball how long does it take to fall 20 m? 20 = (1/2) (10) t^2 t^2 = 4 t = 2 seconds so it will take to seconds to fall. By symmetry it will also take 2 seconds to rise and hit the plane how fast is it going when it hits the ground? u = a...

**physics**

by the way part B is also the average speed times the time x = 5.25 * 5.2

**physics**

a = change in velocity / change in time = ( 0 - 10.5) / 5.2 m/s^2 x = (1/2) a t^2 = (1/2) * a from above * (5.2) * (5.2)

**SCI 207**

I suppose those are the people with expensive houses on the shore. However what is meant by "worst impacts"? If it means losing the most money it may be correct. However wealthy people probably can survive the loss of shore side property without ending up homeless. T...

**physics**

To go from km/h to m/s divide by 3.6 which is 1000 m/km / 3600 s/min a = change in velocity/time (note it is negative) F = m a By the way, this ignores wave resistance which would be a major part of the retarding force.

**chemistry**

P1 V1 = P2 V2 so V2 = P1 V1/P2 I am assuming that these are total pressures and no "gage" pressures. If they are gage pressures add 1 atm to both P1 and P2

**physics**

well, I guess it is ok to use g = 9.81 m/s^2 but we will have to check later if the thing is a significant fraction of an earth radius high. (1/2) m v^2 = m g h v^2 = 2 g h h = v^2/19.6 = 49*10^4 / 19.6 = 25,000 meters that is a small fraction of earth radius so constant g ass...

**Physics**

Look below

**Physics**

If I have this picture right block one on the incline is pulling block two on the level above toward the incline. There is one force pulling block one down the incline and string tension T holding it back Fpull = 4.4 g sin 30 = 2.2 g 2.2 g - T = mu * 4.4 g cos 30 I assume that...

**Physics**

1 g/cm^3*1kg/1000 g* 100*100*100 cm^3/m^3 = 1000 kg/m^3 you know this anyway because the density of fresh water is about 1 g/cc or 1000kg/m^3

**Math 221**

well, if it ends in 0 or 5, divide by 5 26 / 21 that is 13*2/7*3 so there is nothing more to be cancelled.

**American Government**

This is not my field but one thought crosses my mind immediately. It is in the interest of each state to have as few welfare recipients as possible. Therefore each state would feel pressure to provide as little help as possible hoping that the people will decide to move to ano...

**Science**

If you do A and the bread gets moldy with no air, then the mold spores probably did not come from the air.

**Science**

Graph that P V 8 1 4 2 2 4 1 8 Every time you cut the volume in half you double the pressure P V = k = 8 so P = 8/V so yes, confirmed

**math**

a bit over ten gallons a week at about three dollars per gallon = $30

**math**

out of every seven candies 5 are red and 2 are green so out of 5*7 = 35 candies 5*5 = 25 are red and 5*2 = 10 are green B.

**physics**

vertical problem (time and speed same as 104 meter fall): v = Vi - 9.81 t 0 = Vi - 9.81 t t = Vi/9.81 104 = (1/2) g t^2 104 = (1/2) (9.81)(Vi^2/9.81^2) Vi^ = 2 * 9.81 * 104 Vi = 45.2 m/s horizontal problem (constant speed) t = Vi/9.81 = 4.61 seconds u = 53/4.61 = 11.5 m/s tan ...

**physic**

Because I believe that is the correct value for radius of the earth.

**physic**

for earth for example F = G M1 M2 /r^2 = (6.67*10^-11)(5.98*10^24)(67.5)/ (6.38*10^6 )^2 = 66.14 * 10^ 1 = 661 Newtons that better be pretty close to m g or 67.5*9.81 = 662 Newtons

**physic**

F = G M1 M2 / d^2 where G = 6.67*10-11 N m^2/kg^2 I think you mean radius for distance radius of earth = 6.38*10^6 meters

**Physics**

Hey look. I showed you how to do it for the earth mass and man mass. Do the same for the two balls .3 m apart. G * .3 *.3 / 3^2 = G

**Physics**

This is the same as your problem above with the different planets and the weight of the man on each.

**Physics**

same as problem above

**physic**

1609/4.740 and 1609/4.695

**physic**

x = 6 t + (1/2)(2) t^2 = 6(8) + 64 = 112 meters

**history**

import duties ?

**Math**

total area of patio = 240 area of garden = x^2 useable patio area = 12 - x^2 if x is more than 12, you can not walk around the garden

**physics**

better get a CD and try it :)

**physics**

ok, well if I have it right the pin is at the edge of the hole, 0.75 cm above the center of gravity of the CD for a small angle A the restoring moment about that pin is -m g (.0075)sin A = -.0075 m g A = -.0075*.017*9.81 A = -.00125 A the moment of inertia of the CD about its ...

**physics**

sorry, I need a picture.

**physics**

By the way magnetic field lines usually are draw going from N to S OUTSIDE the magnet.

**physics**

1. How would they cross? 2. different constants/r^2 k Q1 Q2/r^2 versus G M1 M2/r^2 see https://www.google.com/search?q=exponential+field+definition&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb#channel=sb&q=exponential+function+definition&re...

**whoops**

14.4 *10^-9 = 1.44 *10^-8

**physics**

k Q/r 9*10^9 * 1.6*10^-19/10^-1 14.4 *10^-9 = 1.44 *10^-10

**algebraic expression**

I don't know.

**physics**

yes, looking for ratio of charge to mass, knowing mass, could calculate charge (slight oversimplification) see: http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/Ryan_McAllister/Slide3.htm

**physics**

potential energy of mass m at surface = -GMmoon m/r = - m (6.67*10^-11) (7.35*10^22) /(1.74*10^6) = m (28.2*10^5) Needs that many Joules of Ke so (1/2) m v^2 = 2.82*10^6 m v^2 = 5.64 *10^6 v = 2.37*10^3 = 2370 m/s by the way: http://www.1728.org/escvel.htm

**physics**

You are welcome.

**physics**

E = 9*10^9 Q/r^2 here Q = 1.6*10^-19 so 9*10^-3 = 9*10^9 (1.6*10^-19)/r^2 r^2 = 1.6 * 10^-7 = 16 * 10^-8 r = 4*10^-4 meters = .4 millimeters

**Math**

using that regression line calculator y = -4.29x + 28.3 (2.5, 17.6)

**Math**

http://www.alcula.com/calculators/statistics/linear-regression/

**Math**

same as above. enough already.

**Math**

It would take you less time to do these problems than to post them.

**Math**

Your problems are all answered by the link I gave you.

**Math**

tan(90-39) = AP/40 so AP = 49.4 tan (90-52) = BQ/40 so BQ = 31.2 so P is (49.4-31.2) or 18.1 km south of Q and 40 km west of q tan theta = 40/18.1 theta = 65.7 degrees east of north from P to Q

**Math**

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

**Math**

The link I gave you does all of these. In fact if you have a normal table handy, all your questions are really answered in it.

**Math**

Use link below for normal curve: http://davidmlane.com/hyperstat/z_table.html

**Math**

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

**Math**

122 z = (122-182)/30 = -2 242 z = (242 - 182)/30 = +2 then use normal table or use: for example http://davidmlane.com/hyperstat/z_table.html result .9545 in that range so .9545*600 = 573

**Math**

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

**Dynamics**

d^2x/dt^2 = 2 t - 1 dx/dt = t^2 - t + c at t = 0, dx/dt = 2 so c = 2 so v = dx/dt = t^2 - t + 2 x = (1/3) t^3 - (1/2) t^2 + 2 t + c when t = 0 x = a so c = 1 x = (1/3) t^3 - (1/2) t^2 + 2 t + 1 so at t = 6 v = 36 -6 + 2 = 32 m/s and x = 67 total distance = 67-1 = 66 assuming x...

**Hunting training**

So would I (but I know nothing about this really)

**Hunting training**

I agree because my spaniel won't hunt.

**PHYSICS**

at ten meters it has dropped 15 meters (1/2) m v^2 = m g h v^2 = 2 * 9.81 * 15 = 294.3 v = 17.2 m/s at 10 m above ground d = (1/2) g t^2 25 = 4.9 t^2 t = 2.26 seconds

**science**

walk north until the arrow flips :)

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