# Posts by Damon

Total # Posts: 31,580

**chemistry**

all except release of oxides

**science**

The moon faces the earth and we only see one side from here. It is stuck rotating 360 degrees every day. Rotation is spinning on your own axis. Changing its rotation rate would not change tides. decreasing distance between earth and sun would effect the height of full moon and...

**science**

Did no teacher do the ping pong ball, tennis ball and soccer ball thing in your class?

**science**

Yes

**science**

I disagree. The tide is high twice a DAY because the earth spins under the moon putting the moon over Gloucester once a day and exactly opposite Gloucester every day. In both cases the water rises either toward the moon when you are under it or away from the moon when you are ...

**Calculus-Math**

b = 4.0 + 0.35 cos (2 pi t/T) where T is the period 5.4 use cos because it is +1, max at t = 0

**Math yes, right**

Looks good to me.

**Physics**

Of course you could do that much more easily with geometry :)

**Oh :) just maybe**

I bet it is 2 d say angle alpha above x axis in xy plane same vector is angle beta to y axis call vector length h then cos alpha = x/h and cos^2 = x^2/h^2 cos beta = y/h and cos^2 = y^2/h^2 sum = (x^2+y^2)/h^2 BUT h is hypotenuse = sqrt(x^2 + y^2) so we have h^2/h^2 = 1 ...

**Physics**

I am sorry, I have no idea what these angles alpha, beta and gamma are for the two vectors. Are they in three dimensions and the angles to the x, y and z axes? In that case the three angles do not define the direction of a vector. The direction depends not only on the angle to...

**Math**

40(4-t) + 80 t = 240 160 - 40 t + 80 t = 240 40 t = 60 t = 2 hours 80 t = 160 miles

**Physics**

You are welcome.

**Physics**

Did not subtract work already done 9*2 = 18 J 72 - 18 = 54 54/9 = 6 meters

**Physical Science**

1. H and O 2. chemical bond H2O yes D

**Math**

(a) constant acceleration, like a spring mass or pendulum or missle, comes back through zero at same speed, opposite direction. omega = +5 rad/s if it was -5 rad /s at start. (b) alpha = d omega/dt = constant = 100 rad/s so alpha R = 1.5 * 100 = 150 m/s^2 (c) Ac = omega^2 R = ...

**Math**

well if I took 2 from 20 it would be 18 so if I took a little more away it would be a little less than 18

**math**

yes, eight is bigger than 2

**math**

10^5 is 100 thousand 10^6 is one million so which is bigger 1.26 million or 1.87 million ?

**Algebra help pls**

or try an infinite number of values for z :)

**Marine Science (Check my answers?)**

4 - A (make connections) 5 - A (eg Georges Bank, Grand Banks of Newfoundland))

**Physics**

117 km/h *1000 m/km / 3600 s/h = 32.5 m/s Train 1 x = 32.5 t -.5 *.2* t^2 x = 32.5 t - .1 t^2 Train 2 x = 1200 + .5 a (t-10)^2 when do they hit? 32.5t-.1t^2=1200+.5a(t^2-20t+100) 32.5t-.1t^2=1200+ .5at^2-10 at +50 a (.5a+.1)t^2 -(32.5+10a)t +(50a+1200)= 0 when does t become ...

**Ms Sue and other tutors https://www.jiskha.com/di**

Please tell Dr Bob a grateful student left a message for him. https://www.jiskha.com/display.cgi?id=1505776109

**Math**

4^4 = 4*4*4*4 = 16*16 = 256

**Social Studies**

Yes, I think it was Muslim long before 1800 and Morocco was the major power around there by then.

**Math**

20*5 = 50*2 = 100

**Algebra**

3.14 R L = S - 3.14 R^2 L = (S - 3.14 R^2) / 3.14 R

**important message for Dr Bob!!!**

Making more sure he sees it :) Those of us who tutor here appreciate your thoughtfulness Steve

**pre algebra**

You are right. It is wrong an-3a +8=b (subtracted an from left side) Yes but I get: 3a+8 = b-an NO -3a + 8 = b - an an - 3a + 8 = b an = 3a+b-8 n = (3a+b-8)/a

**physical science**

You can read speed on your speedometer. It is a scalar. For velocity you need both the speedometer AND a compass. It is a vector. If you move at constant velocity, no acceleration. Acceleration = rate of change of velocity.

**math**

I get 58 degrees below x axis 360 - 58 = 302 counterclockwise from x axis

**math**

:) anyway tan Ø = opposite/adjacent

**math**

eh ? tan Ø = opposite/hypotenuse LOL

**math**

x = 3, so to the right of origin y = -8 so below the origin That is quadrant IV tan A = -8/3 where A is angle below the +x axis so 360 - A

**algebra**

a^n * a^m = a^(m+n) a^n/a^m = a^(n-m)

**try them**

What do you get? Note a^4 = a to the fourth power 12 a = 12*a = twelve times a

**math**

3 x^2 * 4 y^1 * 3 y^1 = 36 x^2 y^2

**Physics huh?**

a = 200438 g's =200438 * 9.81 m/s^2 You have got to be kidding r = 0.69 meters a = omega^2 r solve for omega which is in radians/second divide by 2 pi to get revolutions per second multiply by 60 to get revolutions per minute

**Physics**

v = average speed during stop = 45/2 = 22.5 95 = 22.5 t v = Vi + a t 0 = 45 + a t a = -45/t

**Physics**

G = universal gravitational constant F = G Me m/r^2 G Me and m do not change so F' = G Me m /(2r)^2 = G Me m /4r^2 so 100/4 = 25 N (assuming it has no velocity, like not in orbit :)

**Physics**

sure, it has a negative velocity (leftward) so it ends up at negative, not positive, x

**Physics**

if v is - , a is + v = Vi + a t 0 = -20 + 4 t t = 5 seconds x = Xi + Vi t + .5 a t^2 x = 0 - 20(5) + 2 (25) x = -100 + 50 x = -50

**Physics**

well, eventually maybe h = Hi + Vi t + .5 a t^2 and a = -9.81 0 = 14 + 0 - 4.9 t^2 t^2 = 14/4.9 t = 1.69 seconds v = Vi + a t v = 0 -9.81(1.69) v = - 16.6 m/s

**Physics**

250 W = .25 kw so 4 hours

**Physics**

You are welcome.

**Physics**

Yes Or would Vf^2+Vo^^2+2a(Xf-Xo) work Is really what I used to get the height v^2 = 2 g h

**Physics**

but a is down, negative -30 = 30 - 10 t 10 t = 60 t = 6 seconds (that is the quickest way to do it. I was trying to lead you through everything that is going on.)

**double that Majiri**

That was the time up, but they want total time in the air.

**Physics**

final velocity will be 30 down or -30m/s to get time up: (1/2) m v^2 at bottom = m g h at top so 30^2 = 2 g h h = 900/(2*10) = 90/2 = 45 meters average speed up = 30/2 = 15 m/s so time up = 45/15 = 3 seconds time down is also 3 so 6 seconds in the air

**physics**

336 kilojoules = 80.3 kilocalories = 80,300 calories

**Chem**

6.21 miles in (42/60 + 15/3600)hours

**Physics**

You are welcome.

**Physics**

-2.47 - 9.81 sin 8.7

**Math**

L + 5 = (1/2)(D+5) I want L+5 so it is (1/2)(D+5) and that is all I can say with what I know.

**Math**

1. but it is square so L = W p = 4 w a = w^2 so 4 w = (1/8) w^2 32 w = w^2 w^2 - 32 w = 0 w(w-32) = 0 w = 0 or w = 32 use w = 32 check p = 4w = 128 A = 32 *32 = 1024 1024/8 = 128 sure enough

**calc**

sin 5 pi/6 = sin 150 degrees = -sin 30 = -1/2 csc = 1/sin so yes, it is -2

**Physics**

Fx = 669 cos 24 change in x momentum or impulse = Fx t so 669 cos 24 * .44 = 60 v

**College Physics Question**

v = dx/dt = 5.3 - 22 t a = d^2x/dt^2 = -22 m/s^2

**math**

fill rate = 1/6 pool/hr drain rate = 1/8 pool per hour rate with both = 1/6 -1/8 = 4/24 -3/24 = 1/24 pool/hour so in three hours (1/24 pool/hr )* 3 hr = 1/8 pool filled in first three hours so we still need to fill 7/8 of pool (1/6 pool/hr)* x hr = 7/8 pool x = 42/8 hours to ...

**Physics**

on an x y coordinate system x = -2 y = -2 the magnitude is sqrt (4+4) = 2 sqrt(2) the direction is 45 degrees below -x axis = 180 + 45 = 225 degrees counterclockwise from +x axis

**Physics**

initial x momentum = 20*20-10*10 =+300 initial Ke=.5*20*400 +.5*10*100=4500 final speeds in x direction are u and v so 20 u + 10 v = +300 so v=(30-2u) .5(20)(u^2) + .5(10)(v^2) = +4500 so 10u^2 +5(900-120u+4u^2) = 4500 u^2 + 450 - 60 u + 2 u^2 = 450 3 u^2 -60 u = 0 u = 0 then ...

**math**

prob late = .35*.12 +(1-.35)*.25 = .205 1 - .205 = .8

**stretch from 12 to 8 ????**

k =9 N/.01 meter = 900 N/m if you mean from 8 to 12 potential energy at 12 = (1/2) k (.07)^2 potential energy at 8 = (1/2) k (.03)^2 subtract to get Joules required

**Physics**

final force needed = [1200 *9.81 / 0.30](.5/45)

**Physics**

Rate of WHAT every how many minutes? Please check what you type. Power in = i V = 8 * 150 watts or Joules/second Useful work done per second in Joules/sec = m g h/(60*minutes)

**please proofread**

if 15/16 of 12 atom an element decay in 8minutes HUH? All I can do is guess that 1/16 of the original amount remains after 8 minutes if a = A e^-kt 1/16 = e^-8k ln (1/16) = - 8k -2.77 = -8k k = 0.347 /min

**Physics**

or about 10/6 :)

**Physics/chemistry**

Never heard of a glass insulator? By the way, ANY ionic material in solution as + and - ions conducts. Na+ and Cl- or 2H+ and SO4--

**Physics/chemistry**

i^2 R = power lost to heating resistance high current ---> high loss so for given power in = V i you want high voltage and low current to MINIMIZE losses. That is why long distance power lines are high voltage and are stepped down in your local neighborhood for safer lower ...

**College level algebra**

h^2 + 3 h = 1 take half of 3, square it, add to both sides h^2 + 3 h + (3/2)^2 = 1 + 9/4 = 13/4 (h+3/2)^2 = 13/4 h + 3/2 = +/-(1/2)sqrt (13) h = -1.5 +/- .5 sqrt(13)

**Math**

5(6-1) + 3 5*5 + 3 25 + 3 28

**Math**

2x ? y ? 3z = 2 2x + 2y ? z = 7 -------------------subtract -3 y - 2 z = -5 +3 y + 2 z = +5 ---------------------add 0 = 0 no solution, lines parallel never cross

**geometry**

note that will give you incircle radius of 3 sqrt 3 = 5.2 for side length 6

**geometry**

https://rechneronline.de/pi/hexagon.php

**error repair**

Left out ke about pin at top let x = C-r height of center of ball = x(1 - cos Theta) for small Theta 1 - cos Theta = 1-1+theta^2/2 =theta^2/2 Potential energy = m g x(theta^2)/2 ke of ball about top point = (1/2)mx^2 (d theta/dt)^2 ke of ball around its center = (1/2) I omega^...

**physics**

let x = C-r height of center of ball = x(1 - cos Theta) for small Theta 1 - cos Theta = 1-1+theta^2/2 =theta^2/2 Potential energy = m g x(theta^2)/2 ke of ball about top point = (1/2)mx^2 (d theta/dt)^2 ke of ball around its center = (1/2) I omega^2 I =(2/5) m r^2 omega= (x/r)...

**Geometry**

72 - 4 = 68 60 - 4 = 56

**College Algebra**

if perpendicular than the slope is + 3/7 because it has to be -1/slope of original. so It has to look like y = (3/7) x + b now put that point in to find b 5 = (3/7) (2) + b

**Algebra 2**

You are welcome.

**Algebra 2**

Oh my, it says linear which means of form f(x) = m x + b You assumed that it wnnt through zero but it goes through (0,1550) so in fact it is of form f(x) = m x + 1550 where m is the slope slope = (2950-1550)/4 = 350 so I get f(x) = 350 x + 1550

**tangential acceleration??**

change in angular velocity = 10^5 * 2 pi radians/60 seconds change in time = 2 * 60 seconds so I get 10^5 * 2 *pi /(120*60) multiply that by .095 or just divide previous answer by 60

**physics Notation?**

Is this: m = 1.7 * 10^3 kg and a = 4.75 m/s^2 ????? if so then F = m a F = 1700*4.75 = 8075 Newtons

**Phy sci**

35 miles/hr = 51.33 ft/s assuming constant acceleration average speed during stop = 51.33/2 = 25.67 ft/s distance = 25.67 * 25 = 642 feet

**Math**

(3/7)(22.8) =

**science**

F = m a F = (4000/g)(1) = 4000/g Newtons same F but now mass is 6000/g 4000/g = (6000/g) a a = 4/6 = .67 m/s^2

**HUH**

They speed up and Ke = (1/2)m v^2 increases with temperature, so direct

**You Dont Need ---- Please do not answer if you have no idea**

You have several really far out replies posted. Rusty Gold ????

**Science**

Nickel is an element Fruit juice = mixture salt water = solution of NaCl and others in water rust is a compound (oxide of iron) of iron and oxygen as they showed you Fe2O3 !

**chemistry**

if it disperses it just spreads out, does not change

**Math**

4, 3, and 5 do it because 2 is in 4 4*15 = 60

**Math**

x - y = 8 x = 2y + 3 so 2 y + 3 - y = 8 y = 5 x = 5+8 = 13

**Calculus**

.07 [ 8 x dx - x^2 dx ] at 8 - at 0 .07 [ 8 x^2/2 - x^3/3 ] .07 [ 4*64 - 512/3 ] (.07/3) [12*64 -512] = (.07/3)[256] grams

**Algebra**

x fives 3x ones (x-1) tens sum so far = (4x-1) [26 - (4x-1)] twenties = (27-4x) 3x + 5x + 10(x-1) + 20(27-x) = 120 proceed :)

**Calculus NOTATION?**

Do you mean 6 (5+r^2)^(1/3) ???? dA = 2 pi r dr dP = 2 pi r dr * [whatever you mean] integrate from 0 to 6

**pre- algebrea**

If you mean 14 - a^2 that is 14-9 = 5

**Math**

needs 4 * 20 = 80 feet 80 feet = 24.4 meters call it 25 meters if he has to buy rolls in whole meters 25 * 12 = 100 * 3 = 300

**I do not know**

You did not say if the total enrollment is 40 or if 40 are there today.

**physical**

vertical problem: 2.5 seconds up and 2.5 seconds down v = Vi - 9.81 t at top v = 0 so Vi = 9.81*2.5 = 24.5 m/s up h = Vi t - 4.9 t^2 = 24.5(2.5) -4.9(6.25) = 61.3 - 30.6 = 30.6 meters high at top horizontal problem 49 = u (5) so u = 9.8 m/s tan theta = Vi/u = 24.5/9.8 theta = ...

**Physics**

(a) k Q^2/R^2 repulsive (b) now Q on A and Q/2 on B (also Q/2 on C) so k Q^2/2R^2 (c)1.5/2 = .75 Q on A and still Q/2 on B k*.75 *.5 Q^2 /R^2 = .375 k Q^2/R^2

**Please proofread**

what temp outside? what temp inside? kw needed = 1.3(temp difference)

**math**

from right triangle of hypotenuse s and leg s/2 you get h = (s/2)sqrt 3 so s/2 = h/sqrt3 then area = A = (s/2)(s/2)sqrt 3 = (s^2/4)sqrt 3 and A = (s/2)h = (h/sqrt 3)h =h^2 /sqrt 3