# Posts by Damon

Total # Posts: 31,631

**math**

1.07 and 0.75 first one first, second second one first :)

**math**

try it both ways

**math ( help)**

I know that a 3, 4 , 5 triangle is a right triangle but I can prove it easily anyway because 9 + 16 = 25 or in other words a^2+b^2=c^2 now multiply each side by 15 and get 45, 60 , 75 :)

**Derivatives**

You answered the question you asked, the function is differentiable for all real values of x The derivative is the slope of that straight line, 3 , so 3 and only 3

**physics As**

You have not posted all the information needed. 9.81 is the acceleration of gravity which has nothing to do with this. Why is there a 4 above 128? Please post the complete problem you were given as given. if acceleration and force is constant (1/2) v^2 = F d or initial kinetic...

**Physics**

F = m g = G m M/R^2 so g = G M/R^2 here G = 6.677 * 10^-11 R = 1.738*10^6 g is given = 1.62 solve for M

**physics**

the area under the curve is the distancee

**Physics**

yes

**sorry, typo, 200**

|A+B|^2 = 14.14^2 = 200 not 100 I did not use calculator, knew sqrt 2 = 1.414

**Physics**

A is perpendicular to B so A dot B = 0 AxBx + AyBy = 0 8 Bx + 6 By = 0 and A + B = (Ax + Bx)i+ (Ay+By)j |A+B|^2 = 14.14^2 = (Ax+Bx)^2+(Ay+By)^2 so (Ax+Bx)^2+(Ay+By)^2 = 100 (8+Bx)^2 +(6+By)^2 = 100 but we know By =-(8/6)Bx = -(4/3) Bx plug and chug.

**Physics**

well it is very difficult for A to be perpendicular to both B and C otherwise because j + k and 3 j+k just do not work :)

**Physics**

well, we know they are coplanar if t = 1 not if not

**Physics**

I assume you mean A = i+j+k Is A X B in the same direction as A X C? You can work it out but by inspection you can see that vector A is the same direction as vector C and therefore, A and B (or C and B) define a plane.

**pre calc**

The derivative is SLOPE of the curve at x It does not matter if you move the graph of the function up 7 units, the slope will be the same at each x. Graph it :)

**algrebra 2**

-4(3n+3)+2 -12n -10

**calculus 2**

integrate by parts int u dv = u v - int v du dv = cos 3 x dx so v = (1/3) sin 3x u = 3 x + pi du = 3 dx so u v - (3/3)integral of sin 3x dx put in your limits (3x+pi)(sin 3x)- int sin3x dx at pi/3 minus at pi/6

**physics**

density = mass / volume volume = mass/density I would do it all in cm^3 and grams 1 kg = 1,000 grams

**physics**

F = -k x x = A sin w t v = Aw cos wt a = -Aw^2 sin wt = -w^2 x but F = m a -k x = m(-w^2 x) so w^2 =k/m (2pi)^2/T^2 = k/m k = m (2pi)^2/T^2 = 0.200* (2pi)^2/0.25^2 k = 126 Newtons/meter now back to get A when at max x, energy = (1/2) k x^2 = (1/2) k A^2 so (1/2) k A^2 = 2 ...

**Calculus**

[1/(4x^3-12x^2)]d/dx[4x^3-12x^2] [1/(4x^3-12x^2)][12x^2-24x] [3x-6]/[x^2-3x]

**Physics**

There is no centripetal acceleration before the motion starts. Ac = V^2/R = omega^2 * R V = omega * R = 0 at start so Ac = 0 There is however an angular acceleration alpha = Torque/moment of inertia The tangential acceleration = alpha * R =================== When you stop ...

**Science**

power in Watts * time in seeconds = energy in Joules so 1225 * t = 727 t = (727/1225 )second

**Science**

https://www.jiskha.com/display.cgi?id=1512242770

**Physics**

few and far between.

**math**

s + g in bag at first s-1 = (1/7)(s+g-1) s = (1/5)(s+g-2)

**Chemistry**

you need 2 mols of H2 for every mol of O2 2 H2 + O2 -> 2 H2O or in this problem 4H2 + 2 O2 --> 4 H2O H2 is 2+16 = 18 grams/mol so 4 * 18 grams

**Physics**

did not check arithmetic but that is the right idea

**math**

multiply both sides of the equation by 5 5/5 = 1 4*5 = 20

**Doing just one. The rest are similar.**

we know 5*3 is 15 and two 15s is 30 so (5x-3)(5x-3) = 0 so 5x-3 = 0 x = 3/5 twice because both solutions are the same. That means the vertex of the parabola is on the x axis at x = 5

**History 8th gradconnections academy**

I am no historian but for 2 I would have picked D because the act is about voting rights and for 3 I would have picked C because unlike blacks or indigenous Americans, the Chinese railroad laborers were not citizens and that was used as an excuse.

**As Physics**

Your problems are all the same. You do not seem to have tried any. I will outline this one, period. Initial momentum: P = 4,000 * 2 + 100,000 * 0 = 8,000 That is of course the final momentum as well. 8,000 = (4,000+100,000) v Since they stick together, v is the final speed of ...

**math**

5 mi/3 in look at squares on map 5 miles * 5 miles = 3 in * 3 in so 25 mi^2/9 in^2 45 in^2 * (25 mi^2/9 in^2) = 45*25/9 mi^2 = 125 mi^2

**Math**

I agree that is probably what they want but I could see it as y+5 = -2/ [5(x+3)] which is wrong so I was reluctant to pick one of the listed answers

**Math**

(y+5)/(x+3) = -2/5 y+5 = (-2/5)(x+3)

**Math**

you could use 1+1+1+1+1

**PLZ**

let z = x^2 then you have 3 z^2 -27 z -1200 = 0 or z^2 - 9 z - 1200 = 0 z is about 40 or -30 (you can do quadratic accurately) so x = +sqrt 40 or - sqrt 40 or +i sqrt 30 or -i sqrt 30

**No way**

We are tutors, our job is to help people learn, not to help them bypass learning.

**Physics**

F is up, + F - m g = m a F = m(g+a) = 40 (9.81+3)

**Math**

same numerator, smaller denominator 1/4 is greater than 1/8 :)

**No way !!**

You are just guessing. Think!

**Physics**

F = m a braking so - -6000 = 1100 a a = -5.45 m/s^2 v = Vi + a t at stop 0 = 15 -5.45 t t = 2.75 seconds to stop average speed during stop = 15/2 = 7.5 m/s d = 7.5 * 2.75 = 20.6 meters

**typo ?**

I bet you mean 10x+10y+20z=1850 20x+20y+10z=2200 20x+10y+10z=1500 get rid of x and y in first two by multiplying first eqn by 2 20x+20y+40z=3700 ................> 30 z = 1500 so z = 50 20x+20y+10z=2200 ========================= then third and first 20x+10y+10z=1500 >>...

**pre-algebra**

x + (x-5) = 31 2 x - 5 = 31 2 x = 36 x = 18 x-5 =

**History**

By the way, I am not happy that they left out cod and halibut.

**History**

What unhealthy weed was exported from Jamestown area? What not warm when wet cloth was exported from the southern states? What unhealthy additive was exported from the Caribbean Islands?

**math**

140 * 16

**Physics**

well force up = force down force up at knee = Fk at x = 0 Force up on rope = T at x = .65 weight down at center = 2.6*9.81 at x = .435 forces up = weight down Fk + T = 25.5 N moments about knee = 0 0 = .65T - 25.5*.435 so T = 17.1 Newtons if this is done by a mass on a pulley ...

**Physics**

loss of potential energy = m g h = 3*9.81* 7 = 206 Joules = translational Ke + rotational Ke = (1/2) m v^2 + (1/2)I omega^2 Note I = (2/5) m r^2 v = omega r so 206=(1/2)m v^2 + (1/2)(2/5)m r^2 v^2 412 = 1.4 *3 v^2 v = 9.9 m/s then calculate (1/2) (2/5)(3) v^2

**physics**

You are welcome.

**physics**

r = 0.56/2 = 0.28 meters period = .75 s so the block goes 2 pi r meters in 0.75 seconds v = 2 pi *.28 / 0.75 = 2.35 meters/second F = mass * centripetal acceleration = m v^2/r = 1.5 * 2.35^2/.28 = 29.5 Newtons

**Physics**

v = initial v + a t v = 5 - 0.84 (15)

**Physics**

Interesting, I just answered some of these posted later under different names.

**Science**

Ah well, I saw the question too late.

**Science**

ah, I disagree. The predator highest on the list usually is big in size( whale :) but is small in population numbers. A hawk eats a lot of songbirds.

**Science**

You are welcome, good luck. Either way you could do a good poster.

**Science**

it says "or" not "and" so I would describe how to reduce use of it, or how to use it more than once (steel spoon instead of plastic :), or how to recycle it for use as something else.

**math help**

3 y - 5 = 3 3 y = 8 y = 8/3 =============== or do you mean (y-5)/3 = 1 y - 5 = 3 y = 8

**physics**

which has the lowest ratio of surface area to volume? let volumes all be 1 sphere v = (4/3) pi r^3 = 1 then r = [ 3/(4pi) ]^1/3 r = .620 a = 4 pi r^2 = 4.836 cube v = s^3 = 1 so s = 1 a = 6 s^2 = 6 (so cools faster than sphere) cylinder LOL, depends on height to radius but pi ...

**physics**

I think the arc length is the distance along the circumference here. r theta = 2.55 theta = 2.55/2 = 1.275 radians so I get omega = 1.275/2.30 = 0.554 radians/second he went from 0 to 0.554 rad/s so his average omega is 0.277 rad/s so v = omega r = 0.277 * 1.75 = 0.485 meters/s

**Math**

12 km/hr * 1000 m/km * 1 hr/60 min = 200 meters/min 10 km/hr = 166.7 meters/min distance = d d = 200 (t-4) = 200 t - 800 d = 166.7(t+6) = 166.7 t + 1000 33.3 t = 1800 t = 54.1 minutes d = 200(54.1) - 800 = 10,010 meters = 10 km check 200(54-4) = 10,000 167(54+6) = 10,000

**physics**

F = - G m M/r^2 work done from R to infinity F dr = G m M/R so G M m/R^2 = Ke at surface = (1/2)m v^2 v^2 = 2 G M/R G = 6.67 * 10^-11 M = 7.4 * 10^22 kg R = 1.74^10^6 meters plug and chug

**Math**

2p or often online here 2*p or 2 x p but that is confusing using x both for multiplication symbol and also possibly for a variable name

**Math**

y-3

**Science**

Is your car powered by a solar cell on the roof ?

**Physics**

850/5 = 170 Newtons (actually it is closer to 1/6 ) Remember the mass is the same on both earth and the moon and weight is m * local g

**AP physics multiple choice**

Assuming that the collision happened so fast that the machine swinging the bat put no work in during the collision the angular momentum (of the entire bat/clay system)does not change. The moment of inertia is a little higher due to the mass of the clay so the angular velocity ...

**physics**

in normal operation of a bulb 200 Watts = V^2/R = 120^2/R so R = 72 Ohms now we have two in series so V = 120/2 = 60 volts again watts power = V^2/R = 60^2/72 = 50 watts

**history**

Wait a minute. It is not asking for his role in the war of Texas independence against Mexico but for his role in joining the United States as a state rather than as an independent republic.

**Math**

Draw a long line, mark a point O on the line mark one side of O length a mark the other side length b the total length is then (a+b) Draw a short line through O perpendicular to the first one Draw a short line through O, perpendicular to the long one . Lengths c and d, total ...

**Math**

you mean there is a path of constant width between the garden and the fence? well 23.5 - 14.5 = 9 17.75 - 8.75 better be 9 :) half of 9 is the path width 4.5 feet

**Math**

well right off you see where they cross 5x-7 = 6x+2 so -9 = 1 x so x is -9 at the intersection then at that intersection y = 6x+2 = -54 + 2 = -52 You can check that with the other equation y = 5x-7 = -45 - 7 = -52 sure enough

**Oh ?**

Please look at those answers again and tell us which one makes sense and which three are simply crazy.

**Rachel Carson**

Google "Silent Spring" .

**Physics-Answer Check**

I agree.

**PreCalc**

first division -> a+b+c-1 = 14 second division -> c-a-b+1 = 0 third division-> have to go, continue ;)

**Physics**

work done = 9.81*200 * 2 power = work done / time = 9.81*200 *2/2.2 Watts Wow, like a horse

**physics**

vertical problem: normal force = weight - string up force = 890 - T sin 30 = 890-.5 T horizontal problem: T cos 30 - .2(890-.5T) = (890/9.81) (0.8) solve for T

**Math**

3 meters = 300 cm 8 * 40 = 320 cm need 20 cm more than I have

**Math**

300 / 50 = 6 with nothing left over

**Calculus**

L = 2 w V = L w h = 2 w^2 h = 10 so w^2 h = 5 base area = L w =2 w^2 base cost = 18 w^2 ends area = 2 w h ends cost = 300 w h sides area = 2 L h = 4 w h sides cost = 600 w h total cost = 900 w h + 18 w^2 but h = 5/w^2 c = 900 w (5/w^2) + 18 w^2 c = 4500/w + 18 w^2 dc/dw = -...

**Calculus**

do you mean base = 2 r = 10/(1+pi/4) ?? if that is correct then 2r + 2h + pi r = 20 total height = h + r 10/(1+pi/4) + 2 h + pi(5/(1+pi/4) = 20 10 + 2h(1+pi/4) +5 pi = 20 2h(1+pi/4) = 10-5pi h = (10-5pi)/(2+pi/2) then to get total height add r r+h = 5/(1+pi/4) + (5-2.5pi)/(1+...

**Calculus**

y = m x + b 2 = 6 m + b m=(2-b)/6 when y = 0 x = -b/m so Area = (1/2)b(-b/m) A = -b^2/2m A = -3b^2/(2-b) dA/db = [(2-b)(-6b)+3b^2(-1)]/bot^2 =0 for min or max 3 b^2 = -12b + 6 b^2 3 b^2 = 12 b b = 4 (or zero of course) so y intercept is 4 m = (2-b)/6 = -2/6 = -1/3

**physics**

n1 sin T1 = n2 sin T2 n1 = 1.000 n2 = 1.655 1.000 sin T1 = 1.655 sin 24 sin T1 = .673 T1 = 42.3 degrees

**I see your other problms, try them**

I see your other problems. They are really just like this one. Try them.

**Physics**

component of weight down plane = m g sin 35 friction up plane = .2 m g cos 35 so force accelerating m down plane = m g (sin 35 - .2 cos 35) a = force/m = g(sin 35 - .2 cos 35) distance =(1/2) a t^2 = 8 meters solve for t

**math**

well, 5x is "like" -2x and -10 is "like + 10 so "combine" them and by the way 3x - 0 = 9

**Social Studies**

I assume that each reply will be in the form of a doctoral dissertation.

**Math**

NOT multiplied by 2 radius SQUARED on the right r times r

**Math**

no, the radius is the radius it is r^2 = 0.25 so r = 0.50 (x-k)^2 + (y-h)^2 = r^2 center at (h,k) radius of r

**Math**

I do not know what you are talking about with the first one. It is nott an equation the second one is a circle with center at (3,7) and radius of 0.50

**World History**

She and Martin Luther used to debate in the hallway. I listened at the door.

**Physics**

u = -6.65 m/s u t = -20 + 3 t 20 = (3 + 6.65)t t = 2.07 secs how high? h = 12.45(2.07) - 4.9(2.07)^2 = 25.8 - 21 = 4.8 meters so 4.8 = Vih (2.07)-4.9(2.07)^2 Vih = 12.5 meters/ second check my arithmetic !

**maybe**

If the elevation angle of the cannon is 38.5 degrees then the horizontal velocity of the cannon ball relative to earth is u = 19 - 10 - 20cos 38.5 forever Its location relative to earth from the time of firing is x = u t the initial vertical velocity of the cannon ball is Vi...

**physics**

horizontal U = 20 cos 25 for the whole trip so range = 20 cos 25 * time in air vertical initial speed up = Vi = 20 sin 25 v = Vi - g t where t is time up so t = Vi/g = (20/9.8) sin 25 time down = t = time up so time in air = 2 t so range = 2 t * 20 cos 25 for max height, ...

**mathematics**

(1/2) L B H

**CAlculuss**

so y = 2/x x^2 - 2 (2/x)^2 = 2 x^2 - 8 /x^2 = 2 x^4 - 2 x^2 = 8 let z = x^2 z^2 - 2 z - 8 = 0 (z -4)(z+2)= 0 z = +4 or z = -2 so x^2 = +4 or x^2 = -2 x = +2 then y = 1 x= -2 then y = -1 x = 2 i then y = 2/2i = -i x = -2i then y = +i put these all back in to check

**Hey, one is enough**

I just did the other one, same deal average force = impulse/time

**physics**

(1/2) m v^2 = m g h so v = sqrt(2 g h) impulse = m v = m sqrt(2 g h) = 0.056 sqrt (2*9.81*5.40)

**Physics**

initial I = .00250 * 2.5 = final I = .00250 * Vp + .00500 * Vn Initial Ke = final K =(1/2)(.00250)(6.25) =(1/2)(.00250)Vp^2 + (1/2) (.00500) Vn^2

**Physics**

100*8.5 = 175* Vnorth 75*7.5 = 175*Veast |V| = sqrt(Vnorth^2+Veast^2) T is angle East of north (note, compass angle, not math angle) tan T = Veast/Vnorth

**Physics**

inertia before collision: P = 70*15 + 4.7 * 0 Inertia after collision also = P = (74.7)v compute v kinetic energy after collision = Ke = (1/2)(74.4)v^2, do not bother to compute because at max distance up slope 74.4 g h = that Ke and when it comes back down Ke is that Ke again...