Saturday

September 5, 2015
Total # Posts: 21,876

**physics**

6000 Pascals is 6000 Newtons per square meter. Multiply that by the area of the wall in square meters to get the force in Newtons. The density of water is about 1000 kg /m^3 so the weight of a cubic meter of water is about m g = 1000 * 9.81 = 9810 Newtons so a column of water ...
*July 11, 2015*

**physics**

k Q1Q2/d^2 plug and chug
*July 11, 2015*

**physics**

Hey, have you bothered to try these yourself?
*July 11, 2015*

**physics**

You hear the difference frequency. You want it to be zero. So loosen it more :)
*July 11, 2015*

**physics**

find the frequency from the wavelength lambda = c T = c/f then energy = Lank constant * frequency
*July 11, 2015*

**math**

8 y = -5 x - 5 1.6 y = -x - 14 slope of first = -5/8 slope of second = -1/1.6 which is -5/8 therefore, no, they have the same slope and are either parallel or identical.
*July 11, 2015*

**Math**

2 L + 2 w = 80 or L + w = 40 L w = 300 so w = 300/L so L + 300/L = 40 L^2 - 40 L + 300 = 0 (L-30)(L-10) = 0 try L = 30 and w = 10
*July 11, 2015*

**math**

LOL - close enough, a short lunchtime walk.
*July 11, 2015*

**math**

MIT, Ocean Engineering. BSc in Physics but went back later for engineering doctorate and taught engineering.
*July 11, 2015*

**math**

Anyway, find the total time for the round trip by adding the time out and the time back. Then divide 240 miles by the time in hours
*July 11, 2015*

**math - typo?**

Well did he go 60 or 40 on the way back?
*July 11, 2015*

**physics**

constant horizontal speed = 22 cos 45 so time to fence = t = 100 /(22 cos 45) so how high is it at time t? h = initial height assume 0 + [ 22 sin 45] t - (1/2)(9.81) t^2 That gives you h in meters. Convert to feet to see if it is higher than five feet.
*July 11, 2015*

**Algebra?**

huh ? multiply the side length of a square by four to get the perimeter.
*July 11, 2015*

**Career choice advice needed**

I clicked on this only because the title was in Nederlands (of Afrikaans). It would be wise to put the subject in the title so that you get a teacher who knows something about the subject (I really do not, particularly in South Africa)
*July 11, 2015*

**physics**

every second a volume of .5 m * .01 m^2 = .005 m^3 comes out of the pipe. 2700 kg/m^3 * .005 m^3/second = 13.5 kg/s
*July 10, 2015*

**algebra**

x, x and (x+5) 3 x + 5 = 26 so 3x = 21 x = 7 x = 7 x+5 = 12
*July 10, 2015*

**st joan of arc**

tan 48 = height of building/60 tan 56 = height of top of antenna/60 if you want the height of the antenna itself, subtract.
*July 10, 2015*

**Physics**

7.9/2 = 3.95 so center of plank is 3.95 from outer end which is 3.95 - 3.5 = .45 inside the edge of the platform so for equilibrium 130 (.45) = 31 x x = 1.89 out from edge
*July 9, 2015*

**Physics**

k Q1 Q2 / r^2 note r^2 not r so 1. yes 2 no 3 no 4 yes if you mean 1/r^2 5 not necessarily, Like charges repel.
*July 9, 2015*

**Physics - what ?**

equation for what? Did you try to copy and paste something? That will not work here.
*July 8, 2015*

**math (algebra)**

r = 1/d r = 1/(2r) r^2 = 1/2 pi r^2 = area = pi/2
*July 8, 2015*

**Calculus**

f(x) = |x-2|
*July 8, 2015*

**Calculus**

divide top and bottom by x (5 x^2 + x - 1)/3
*July 8, 2015*

**david college**

I would not have noticed this if Ms. Sue had not said it was Physics. I never took David College.
*July 8, 2015*

**david college**

The charge is the same on each of them. Where else would the electrons on the low side of the top one come from but the high side of the low one :) C = Q/V for each and the voltages add so 100 volts = V1 + V2 100 = Q1/C1 + Q2/C2 but Q2=Q1 = Q so 100 = Q/C1 + Q/C2 = Q (C1+C2)/...
*July 8, 2015*

**Physics**

T is tension if the slope of the plane is 32 degrees component of weight down plane = 10 (9.81) sin 32 which is trying to accelerate the mass down the slope so if acceleration up slope is a then T - 98.1 sin 32 = 10 a now the hanging mass force down = mg - T 98.1 - T = 10 a ...
*July 8, 2015*

**No figure**

This is kind of challenging without the figure but all you really need is F = m a and weight = mass * local gravity
*July 8, 2015*

**physics**

force, direction, distance from A F , up (assumed) , x (unknown) 2500 , down , 0 4000, up , 8 10,000, down , 12.5 3000, up , 21 3500 , down , 25 sum of forces up = 0 so -2500+4000-10000+F+3000-3500 = 0 F -5500 = 0 so F = +5500 up sum of clockwise moment = 0 about A 2500*0 -...
*July 8, 2015*

**maths**

so those opposite angles are 130/2 = 65 sum of all the angles is 360 so 130 + 2 theta = 360 theta = 115 so two angles of 65 deg and two angles of 115 degrees
*July 8, 2015*

**maths**

90-32
*July 8, 2015*

**Physics (Kinematics Check)**

actually I think vi, your initial speed is zero we do not know vf, the final speed. All we know is that it fell 4 m. h = Hi + vi t - (1/2) g t^2 0 = 4 + 0 - (1/2)(9.81) t^2 so t^2 = 4/4.9 t = .9035 seconds to fall 4 meters the average speed is 4 meters/.9035seconds or 4.43 m/s...
*July 8, 2015*

**Calculus**

Hmmm, well what you are telling me is that the value of a function at x = a is the same as the limit of the value of the function as x--->a That might usually be true, but what if the function has a different limit depending on which side you approach a from? I am thinking ...
*July 7, 2015*

**Math**

2 minutes = 120 seconds (11 words / 8 seconds) 120 seconds = 165 words
*July 7, 2015*

**Math**

40 /(2/3) = 120/2 = 60
*July 7, 2015*

**Chemistry-History-ish**

Good except the first sentence is misleading. Those experiments did not discover "radioactivity". They were studies into the structure of matter as described in the problem statement. For discovery of radioactivity see "Madame Curie". for example : http://...
*July 7, 2015*

**Math**

LOL, draw an equilateral triangle with centroid at origin or a circle with center at origin and radius = 1. for the circle a it just gets to be a bigger circle (so it is similar) b same deal, smaller circle but similar. c try it, I think it will be kind of elliptical (do you ...
*July 7, 2015*

**Chemistry**

carbon monoxide This makes the difference clear between carbon monoxide CO and carbon dioxide CO2 You do not need to say mono carbon monoxide or mono carbon dioxide because they are both one carbon and there is no confusion.
*July 7, 2015*

**physics**

d omega / dt = alpha = (1400-428)/6.26 = 155 rad/s^2 which is angular acceleration part b theta = 428 t + (1/2)(155)t^2 but t is 6.26 so theta = 5722 radians which is part a
*July 7, 2015*

**Physics**

For example Fx = F dot i = |F|cos of angle to x axis
*July 7, 2015*

**Physics**

Components of vectors such as components of a force vector are also scalars. They are the dot product of the vector with the unit vector in the component direction.
*July 7, 2015*

**Physics**

I am inclined to disagree. Displacement is a vector with magnitude and direction. DISTANCE is the scalar magnitude of displacement. However Work, for example in Joules, is clearly scalar and has no direction. It is a dot product of force and displacement vectors and has no ...
*July 7, 2015*

**Physics**

255 cos 60 * 15 assuming that the force is at 60 degrees from the motion. 1912 Joules
*July 7, 2015*

**American History**

The colonists made the natives miserable, and they did not even know that the Europeans brought the diseases that killed most of them. See for example http://www.history.com/topics/native-american-history/king-philips-war
*July 7, 2015*

**physics**

V entry = a t = 6.3*4.1 = 25.83 m/s v = 25.83 + 6.3 t x = 25.83 t + (1/2)(6.3) t^2 for the second car x = 70.7 t so 70.7 t = 25.83 t + 3.15 t^2 3.15 t^2 - 44.87 t = 0 t (3.15 t -44.87) = 0 so they are at the same x at sthe start of course and at t = 44.87/3.15
*July 7, 2015*

**pysics**

Immediately after drop its vertical speed is zero, so no drag. therefore m a = m g and it accelerates down at 32 m/s^2 as it builds up speed and the chute deploys, the air drag increases at about proportional to speed squared until the drag force up equals the m g down and the...
*July 7, 2015*

**math**

You are welcome.
*July 7, 2015*

**math**

on your graph mark the point where x = 1 and y = -3 from there go right one and down one (slope of -1) and mark a second point. draw a line through those two points.
*July 7, 2015*

**math**

y = m x + b put in slope m y = -1 x + b put in point y = -2 where x = 1 -3 = -1(1) + b so b = -2 so y = -x -2
*July 7, 2015*

**Chemistry**

mass * ( heat of fusion + heat capacity * 100 + heat of vaporization)
*July 7, 2015*

**physics**

mg downward 30 N upward net downward = m g - 30 g is not in Newtons but in m/s^2. It is more like 9.81 m/s^2 on earth but ok, use 10 m/s^2 net downward = 5 kg ( 10 m/s^2) - 30 = 50 - 30 = 20 Newtons
*July 7, 2015*

**statistics**

Sure looks like .7 to me. The ones not in the window have nothing to do with your problem.
*July 7, 2015*

**science**

although it also has rotational energy Kinetic spin energy = (1/2)I omega ^2 = (1/2)(2/5) (.2)(R^2) omega^2 but v = R omega so add (1/2) (2/5)(.2) (25)
*July 7, 2015*

**science**

(1/2) m v^2 = .5*.2*25 Joules
*July 7, 2015*

**physics**

west inertia before = west inertia after 2000 * 20 = 5000 * Vwest south inertia before = south inertia after 3000 * 20 = 5000 * Vsouth V = sqrt (Veast^2+Vsouth^2) tangent of angle west of south = Vwest/Vsouth compass course = 180 + that angle
*July 7, 2015*

**Math**

.2*2 + .3*1 -.3*2 -.2*0 .4 + .3 -.6 - 0 .1 I agree
*July 5, 2015*

**American history**

............I have already intimated to you the danger of parties in the State, with particular reference to the founding of them on geographical discriminations. Let me now take a more comprehensive view, and warn you in the most solemn manner against the baneful effects of ...
*July 5, 2015*

**Calculus**

dy/dx = slope = 2*5 x - 4 + 0 The 12 has no effect on the slope The slope is a straight line with y intercept of -4 and slope of 10 The 5 is half the slope of the derivative
*July 5, 2015*

**math**

5,747 * 1.021^n = 36,000,000 1.021^n = 36,000,000/5,747 = n = log (36,000,000 / 5,747)/log 1.021 = 421 ============================ check 1.021^421 = 6307 6307*5,747,000 = 3.6*10^10 = 3.6*10,000,000,000 =36,000,000,000 sure enough
*July 5, 2015*

**science**

weight * tan 4 = m a m g tan 4 = m a a = g tan 4
*July 5, 2015*

**maths**

LOL, should have checked that !
*July 5, 2015*

**maths**

We know that (x-sqrt 2) is a factor 6 x^3 + 2 x^2 - 10 x -4 sqrt 2 = 0 (x-sqrt 2)( a x^2 + b x + c) = 0 well, c better be 4 (x-sqrt 2)(a x^2 + b x + 4) = 0 now I will use distributive property to split this up x (a x^2 + b x + 4) -sqrt 2 (a x^2 + b x + 4) = 0 x terms: 4 x - b ...
*July 5, 2015*

**Math**

The first roll has no effect what so ever on the results of the second roll. They are independent events. Dependent events are those where the first outcome has an effect on the second. For example if you have two green balls and two red balls in a hat. The probability of ...
*July 5, 2015*

**physics**

There is no such thing as a force of 2 kg, sorry
*July 5, 2015*

**Math**

x^2 = t^2 cos^2 y^2 = t^2 sin^2 x^2 + y^2 = t^2(cos^2+sin^2) = t^2 but t^2 = z^2 so x^2+y^2 = z^2
*July 5, 2015*

**math**

36 + .2(450-100) assuming one day
*July 4, 2015*

**physics**

oh max acceleration magnitude = A w^2 = 5.6*10^-7 * (5040)^2
*July 4, 2015*

**physics**

harmonic motion with w = 2 pi *frequency or 2 pi/period y = A sin w t dy/dt = v = A w cos w t d^2y/dt^2 = a = -A w^2 sin wt = -w^2 y here v max = Aw = 2.82*10^-3 and A = 5.6*10^-7 so w = 2 pi f = 2 pi/T = 2.82/5.6 * 10^4 = .504*10^4 = 5040 radians/s f = 5040/2pi = 801 Hz T = 1...
*July 4, 2015*

**physics**

You are welcome.
*July 4, 2015*

**physics**

F = k x k = 82/.0191 F = (82/.0191) * .0520
*July 4, 2015*

**phys**

(I wonder if whoever gave you this problem really thought out the implications of the landing :)
*July 4, 2015*

**phys**

h = Hi + Vi t - 4.9 t^2 assume the road was level so Vi = 0 1.5 = 20.2 + 0 - 4.9 t^2 4.9 t^2 = 18.7 t = 1.95 seconds in the air to fall 18.7 meters so how far did he go horizontal in those 1.95 seconds? d = u t 60 = u * 1.95 u = 30.7 meters/second horizontal for the whole jump...
*July 4, 2015*

**science 207 lab wk 5**

How on earth would we know what is in wk 5 of science 207? We are not at your school or perhaps even in your country.
*July 4, 2015*

**Science**

4.9 t^2
*July 4, 2015*

**Science Help Not sure**

Ui = initial speed = 126*10^3/3600 = 35 m/s 65-126 = -61*10^3 meters / 3600 seconds = -16.94 m/s speed change -16.94/8 = -2.12 m/s^2 acceleration d = Ui t - (1/2) a t^2 = 35*8 -(1/2)(2.12)(64) = 212 m so A
*July 4, 2015*

**Science**

v = a t hey, try some of these yourself !
*July 4, 2015*

**Physics**

Vi up = 15 sin 30 = 7.5 m/s initially u = 15 cos 30 = 13 m/s forever Hi = 40 then h = Hi + Vi t - 4.9 t^2 0 = 40 + 7.5 t - 4.9 t^2 or 4.9 t^2 - 7.5 t - 40 = 0 t = [ 7.5 +/- sqrt(56.25 + 784) ] / 9.8 use + root of course t = 3.72 seconds then v = Vi - 9.8 t = 7.5-36.5 = -29 m/s...
*July 4, 2015*

**physics**

3 sin thete = 2 theta = 41.81 V across = 3 cos theta = 2.24 mi/hr (1/4)/2.24 = .112 hr = 6.7 minutes He has zero velocity parallel to the shore (that is the whole point) However he has speed of 2.24 mi/hr perpendicular to the shore.
*July 4, 2015*

**Physics**

well, I suppose they both have the same acceleration, call it a The total mass is 5000 kg The total force on the system is 6000 N so a = 6000/5000 = (6/5) m/s^2 Now how much of that is on the truck? F = 3000 a = 3000 (6/5) = 3600 Newtons from the car on the truck so the force ...
*July 3, 2015*

**physics**

All yo can really find in this world is DIFFERENCES in potential energy. In this case, whoever wrote the question probably expected you to define zero potential at the FLOOR so the h you use for part 1 which is 6.5 -2.5 = 4 is NOT the h you use for part 2 for part 2, use the ...
*July 3, 2015*

**physics**

LOL, it takes time, it is almost midnight, and I have to work tomorrow.
*July 2, 2015*

**physics**

v = omega r 1. 6.12 * 2.20 = 13.464 m/s 2. 6.12 * 15.2 = 93.024 3. 6.12 * 3.15 = 19.278 (1/2) m v^2 1. .5 * 6.36 * 13.464^2 = 577 Joules 2. you can do the next two 3. add them I = m r^2 1. 6.36 (2.2)^2 = 30.8 2. you can do 3. you can do add them for total I Ke = (1/2) I omega^...
*July 2, 2015*

**physics**

There are only two horizontal forces in this problem, at the wall and at the ground. Therefore they are equal and opposite, call the magnitude F now balance vertical forces 886 + 350 = force down = 1236 N that is therefore the normal force up at the ladder base the max ...
*July 2, 2015*

**math**

4 = 2^2 so (2^2)^(x+2) = 2^x but (a^b)^c = a^(bc) so 2^(2x+4) = 2^x 2x+4 = x x = -4
*July 2, 2015*

**math**

Now you can solve what I gave you for x which is the pounds of nuts with cashews.
*July 2, 2015*

**math**

5 t^2 - 7 t - 1 = 0 t = [ 7 +/- sqrt(49+20) ]/ 10 t = [ 7 +/- sqrt(69) ] / 10
*July 2, 2015*

**math**

3.95 x + 1.15 = 1.70 3.95 x = .55 x = .139 yes then .5 - x = .361 ------------------ check 6.25 * .139 = .869 2.30 * .361 = .830 ------------------- add ****** .5 lbs = 1.699 or in other words 1.70
*July 2, 2015*

**math**

x with cashews costs 6.25 x (.5-x) with peanuts costs 2.30 (.5-x) so 6.25 x + 2.30(.5-x) = 1.70
*July 2, 2015*

**Math**

if she works 40 hours per week (we are just guessing that), then she worked 80 hours for $383 383/80 = $4.7875 per hour
*July 2, 2015*

**Math**

The y intercept is where the line hits the y axis, in other words when x = 0 that means that in the equation of the line y = m x + b the y intercept is where x = 0 and y = b saying a point is on -3 and the other on + 5 does not help me You have to say for example at one point ...
*July 2, 2015*

**Finite**

maximize p = 8x + 10y subject to .6x + .45y <= 400 .4x + .55y <= 300 =============================== Vertex Lines Through Vertex Value of Objective (566.666667,133.333333) .6x+.45y = 400; .4x+.55y = 300 5866.666667 Maximum (666.666667,0) .6x+.45y = 400; y = 0 5333.333333...
*July 2, 2015*

**Finite**

http://www.zweigmedia.com/RealWorld/LPGrapher/lpg.html
*July 2, 2015*

**Finite**

cc = .6 x + .45 y </= 400 rb = .4 x + .55 y </= 300 income = i = 8 x + 10 y objective, maximize graph those functions, check the corners
*July 2, 2015*

**Finite Math**

well, in that first column I would like to see 1 0 0 so I would multiply row 1 by 2 subtract the result from row two and put that result where row 2 is then I would multiply row 1 by 3 instead of by 2 and subtract the result from row three, placing the result in row three.
*July 2, 2015*

**Applied Mathematics ( Mechanices**

a ) m g b ) m(g+5) c ) m(g-5) on earth g is about 9.81 m/s^2
*July 2, 2015*

**physics**

the braking force is opposite to the direction of motion, so we are doing negative work on the train delta W is negative Are we putting heat into the train? I think not. In fact heat is going out into the air as the brakes heat up. delta Q is negative So I suspect that the ...
*July 2, 2015*

**mathematics**

0.400 * 6.00 = $2.40
*July 2, 2015*

**Physics**

a = dv/dt = 4 i + 14 t F = m a 40 = 4.6 sqrt (4^2 + 14^2 t^2) (40/4.6)^2 = 16 + 196 t^2 solve for t use that t to get v and a Then v dot a = |v||a| cos theta
*July 2, 2015*

**Physics**

tension T force F horizontal vertical: T cos 32.9 = m g horizontal: T sin 32.9 = F
*July 2, 2015*

**algebra**

or ln (2-x) = 14 e^{ln(2-x) = 2-x so 2-x = e^14 x = 2 - e^14 x = - 1202602
*July 1, 2015*

**Differential Equation**

hmmm, not sure but dy/dx = [(1-y^2)/(1-x^2) ]^.5 dy/(1-y^2)^.5 = dx/(1-x^2)^.5 let y = sin p let x = sin r dy = cos p dp and dx = cos r dr cos p dp/cos p = cos r dr/cos r dp = dr
*July 1, 2015*