Saturday

August 1, 2015

August 1, 2015

Total # Posts: 21,584

**Physics**

up is + a) gravity force down = weight = -m g = -1210*9.81 = -11870 N b) F is positive up F = m a = 1210(-1.4) F = - 1696 N c)gravity pushing down, helicopter pushing up d)lift is up lift - 11870 = m a = -1696 lift = 11870 - 1696 = 10176 N up
*February 22, 2015*

**Vectors Math**

Your notation is a mystery to me. The magnitude of the projection of A on to A is |A| cos T where T is the angle between A and B but |A| cos T = |A| |B| cos T /|B| which is A dot B /|B| Now we need a unit vector in direction B That is B/|B| so in the end we need A dot B * B /|...
*February 22, 2015*

**Vectors**

"bearing" means what direction you LOOK. "heading" means what direction you point the vehicle. As in: We were heading north when we took a bearing of 90 degrees on a lighthouse east of us.
*February 22, 2015*

**Vectors**

Math teachers do not know navigation English. It drives me crazy. You do not head on a bearing. You sail or fly on a heading. the plane is flying on a heading of 200 (about SSW) at 400 km/h the plane is also moving at 100 km/h southwest which is 180+45 = 225 degrees You can do...
*February 22, 2015*

**Physics**

C = q/V so V = q/C so q1/C1 + q2/C2 + q3/C3 = 58 but q1=q2=q3 becaue where else are the electrons to come from or go to? so 1/C1 + 1/C2 + 1/C3 = 58/ q 10^6 (1/3.83+1/5.89+1/12.9 = 58 /q 10^6 (.508) = 58 / q q = (58/.508)10^-6 V = (58/.508)/3.83 = 29.8 volts
*February 21, 2015*

**College Physics**

900(1.0)+ Tright(3) so Tright = 300 N Tright + Tleft = 900 so Tleft = 600 N
*February 21, 2015*

**college physics**

been there, done that, see above
*February 21, 2015*

**Physics**

C = q/V so V = q/C so V = qA/CA = qB/CB and E = (1/2) q V = (1/2) C V^2 5.7*10^-5 = (1/2)(17*10^-6)V so V = 6.71 volts then 6.71 = (qB/6.9)10^6
*February 21, 2015*

**physics**

A steel ball with a mass of 0.65 kg is swinging in a circle with a radius of 1.3 meters at a speed of 17m/s. What is the centripetal force?
*February 20, 2015*

**Physics**

3.6m/5 = .72 square root .72= .8485*24m/sec=20.36m it will travel 20.36 meters
*February 20, 2015*

**Physics**

A baseball is thrown horizontally from a height of 3.6 meters at a speed of 24 m/sec. How far will it travel along the ground?
*February 20, 2015*

**Math Ms Sue**

By the way 4 * 6 = 6 * 4 That is called "Commutative property of multiplication" which is grade three this week for my grandson's class.
*February 18, 2015*

**Math Ms Sue**

area of rectangle = length times width 4 * 6 or using your notation 4 x 6
*February 18, 2015*

**physics**

Sure looks like zero to me. 2 sin 30 = 1
*February 18, 2015*

**Physics**

normal force = m g cos 27.7 friction force up slope = mu m g cos 27.7 gravity component down slope = m g sin 27.7 so m (1.25) = m g sin 27.7 - mu m g cos 27.7 mu g cos 27.7 = g sin 27.7 - 1.25 solve for mu
*February 18, 2015*

**english**

because
*February 18, 2015*

**math/Do not understand**

These picks are independent. Picking a male student does not affect the following pick of a female student. Therefore the answer is simply the product of the two probabilities. 153 + 357 = 510 males male probability = 153/510 = .3 145 + 355 = 500 females female probability = ...
*February 18, 2015*

**Physics**

omega = radians/s = 2 pi/.5 = 4 pi Ac = omega^2 R = (4 pi)^2 * .1 F = m Ac = .012 (4 pi)^2 (.1) increases as omega^2 so 2^2 = 4 times
*February 18, 2015*

**Physics**

the total = 14.7 so 3.5 + 1.4 + V3 = 14.7 R3 = V3/(7*10^-3)
*February 18, 2015*

**physics**

Ke = .5 m v^2 .5 (7)(2.15)^2 = .5 (.0024) v^2 v^2 = (7)(2.15)^2/.0024
*February 17, 2015*

**physics**

(a) 150 * 5.5 Joules (b) no acceleration so work done by friction = 150 * 5.5 mu m g *5.5 = 150 * 5.5 mu = 150/(45*9.81)
*February 17, 2015*

**physics**

east distance = x = 4 + 2 cos 50 south distance = y = -2 sin 50 d = sqrt ( x^2 + y^2 )
*February 17, 2015*

**Math**

.015(500) + .01 (241.23)
*February 17, 2015*

**math**

S(5) = 125 -125 + 4 = 4 v = 3 t^2 - 10 t v(5) = 75 - 50 when is v = 0? 3 t^2 - 10 t = 0 = t(3 t - 10) t = 0 or t - 10/3 a = 6 t - 10 a(2) = 12 - 10 = 2
*February 17, 2015*

**Calculus**

he said at (0,0) the slope is 2 That is a line through the origin with slope = 2 y = 2 x + 0
*February 17, 2015*

**Business Math**

paid 5.50 dollars for 100 dollars that is 100(5.50/100) = 5.5 percent in two weeks or 2.75 percent per week 2.75 * 52 = 143 percent per year. Which is huge!
*February 16, 2015*

**Algebra typo ???**

b a^2 This question means nothing to me, sorry.
*February 16, 2015*

**phyic**

G = 6.67 * 10^-11 N m^2/Kg^2 Sun mass = 1.99 * 10^30 Kg Jupiter mass = 1.89 * 10^27 Kg d= 7.78 * 10^11 m F = G Msun Mjup / d^2 =[6.67*1.99*1.89/60.5]10^[-11+30+27-22] = .141 * 10^24 = 1.41 * 10^23 Newtons
*February 16, 2015*

**math**

You fixed the speed at 5 d = 5 t distance, d, depends on how long you walk ,t We are assuming that the number of credits earned is a function of (dependent on) age age is independent credits is dependent There is no function implied here, in fact there might be multiple values...
*February 16, 2015*

**math**

51 = 3 m
*February 13, 2015*

**Physics**

work = charge * voltage work in Joules charge in Coulombs voltage in Volts 133/3 = 44 1/3 Volts
*February 13, 2015*

**Physics**

Do not understand your notation. Do you mean 2.13 * 10^8 Volts ???? anyway energy in Joules = potential in Volts * charge in Coulombs
*February 13, 2015*

**kayli**

molecules
*February 13, 2015*

**math**

All three of us got the same answer.
*February 13, 2015*

**math**

10 ft/min (60 min/1h)(1 mi /5280 ft) = 600/5280 mi/h = 0.1136 mi/h
*February 13, 2015*

**pre cal 11**

You are welcome.
*February 13, 2015*

**pre cal 11**

If tn = -4 + (n-1)6 then tn = -4 + 6 n - 6 or tn = 6 n - 4 -6 which is 6 n - 10 sure enough
*February 13, 2015*

**pre cal 11**

There are 7 posts including the two end ones. That means six equal spaces between posts 42/6 = 7 meters (note, number of spaces = number of posts - 1)
*February 13, 2015*

**Physics**

28.5 cm/s * 2.88 cm^2 = 82.1 cm^3/s volume flow rate so mass flow rate is 82.1 cm^3/s * 1.03 g/cm^3 = 84.5 g/s
*February 13, 2015*

**maths**

A work/day = 1/16 B work/day = 1/12 2(1/16) + x(1/16 +1/12) = 1
*February 13, 2015*

**Physics Dynamics**

work done against friction = Initial PE - final Ke = Force of friction * distance down slide = mu * normal force * distance Now where is your work?
*February 12, 2015*

**Math**

ds/dt = v = -4 (2t) /t^4 = -8/t^3 if t = a v = -8/a^3 if t = 1 v = -8/1 = -8 if t = 2 v = -8/8 = -1 if t = 3 v = -8/27
*February 12, 2015*

**Algebra 1**

6 a + 2 s = 40 5 a + 12 s = 85 multiply first one by 6 36 a + 12 s = 240 5 a + 12 s = 85 ------------------ subtract 31 a = 155 a = $5 now find s
*February 12, 2015*

**Physics**

so the magnitude is 3.31 kg m/s
*February 12, 2015*

**Physics**

-29 m/s - (+29 m/s) = -58 m/s velocity change change in momentum = -.057(58) kg m/s
*February 12, 2015*

**Physics**

Ac = v^2/R = 100/20 = 5 m/s^2 so F = m g + 5 m = (9.81+5)m = 14.81 m so F = 14.81*85 = 1258 Newtons f = change in momentum / time change in momentum = 85*10 = 850 kg m/s time = distance/average speed = 1.5/5 = .3 seconds so f = 850 kg m/s / .3 s = 2833 kg m/s^2 = 2833 Newtons
*February 12, 2015*

**math**

(1/2) x = 3 x = 6
*February 12, 2015*

**Math**

HE HAD 280 dollars. That is the answer. It is not a fraction.
*February 12, 2015*

**Math**

he started with x he spent 3/7 of x then he had 4/7 of x left he then gave his sister 1/4 of 4/7 of x so he was left with 3/4 of 4/7 of x that is 120 so 3/4 * 4/7 * x = 120 3/7 * x = 120 x = 40*7 = 280 =========================== NOW spend 3/7 * 280 = 120 280 - 120 = 160 left ...
*February 12, 2015*

**Math**

Look at this simpler problem: http://www.jiskha.com/display.cgi?id=1423783632
*February 12, 2015*

**Math**

He spent 3/7 which left him with 4/7 !!! 7/7 - 3/7 = 4/7 then he gave away 1/4 of his 4/7 1 - 1/4 = 3/4 so he is left with 4/7 * 3/4
*February 12, 2015*

**math**

HUH ? 120.25 + (7/28)^(3/7) ??? but 7/28 = 1/4 = .25 120.25 + .25^.42857 ??? 120.25 + 0.55 = 120.80
*February 12, 2015*

**Physics**

You have to tell us the angles from vertical or horizontal or what. if from horizontal T1 cos 45 = T2 cos 30 .707 T1 = .866 T2 T2 = .816 T1, so T1 is the one that will break m g = T1 sin 45 + T2 cos 30 m g = .866 T1 + .866 (.816) T1 m g = .866 T1 + .707 T1 = 1.57 T1 m g = 1.57...
*February 12, 2015*

**Math**

I am getting a bit bored with this question as well.
*February 12, 2015*

**Math**

he was left with 4/7 he gave 1/4 of the 4/7 to his sister so he was left with 3/4 of the 4/7 so (3/4)(4/7)x = 120 (3/7) x = 120 x/7 = 40 x = 280
*February 12, 2015*

**math**

1 - 3/7 = 4/7 is remainder (4/7) x - 3 = 120
*February 12, 2015*

**TYPO ???**

5 seconds up, 5 seconds down do vertical problem first with Vi = initial velocity component up v = Vi - g t at top v = 0 0 = Vi - 10 t but t = 5 seconds so Vi = 50 m/s IF YOU LAUNCH AT 10 m/s, YOU CAN NOT STAY IN THE AIR TEN SECONDS!
*February 12, 2015*

**Science**

If there are no mutations, there are no changes with generations, no adaptation of beak lengths or anything.
*February 12, 2015*

**Science**

You are welcome.
*February 12, 2015*

**Science**

n = 2 , 3, 4, 5, 6 ,7 ..... n^2 = 4 , 9 , 16, 25,...... 1/n^2 = 1/4 , 1/9 , 1/16 .....
*February 12, 2015*

**Science**

so did I :)
*February 12, 2015*

**Science**

1/n^2
*February 12, 2015*

**math**

100(3/4) = 300/4 = 75
*February 12, 2015*

**math**

sorry, slope intercept form is y = -(1/2) x + 1/2
*February 12, 2015*

**math**

2 y = -x + 8 y = -(1/2) x + 4 so slope = -1/2 -2 = -(1/2) 5 + b -2 = -2.5 + b b = .5 = 1/2 so y = -(1/2) x + 1/2 2 y + x = 1
*February 12, 2015*

**Math**

x in 1900 y in 2015 x = .64 y so y = 1.56 x so y now is 156 percent of x which is an increase of 56 percent
*February 12, 2015*

**Math**

(4/7)(3/4) x = 120
*February 12, 2015*

**Physics**

d = (1/2) g t^2 6.9 = 4.9 t^2
*February 12, 2015*

**Physics**

horizontal x = 100 + 35 cos 35 vertical y = 35 sin 35 or sqrt(x^2+y^2) at tan^-1(y/x) above x axis
*February 12, 2015*

**Physics**

There is no force on the ball after it its release so it continues at 4,000 km/s while the ship accelerates away from it. Therefore: -6 m/s^2 Think, how does your head move when you accelerate a car as opposed to driving straight at constant speed.
*February 12, 2015*

**math**

3/2 is bigger than 1 4/9 = 13/9
*February 12, 2015*

**linear algebra**

well, we agree this time :)
*February 12, 2015*

**linear algebra**

I am going to call c1 = a c2 = b c2 = c +3a + 1b -11c = 0 +3a + 2b -13c = 0 -1a - 3b + 9c = 0 -b+2c = 0 from first 2 so b = 2 c +3a + 2b -13c = 0 -3a - 9b +27c = 0 from second 2 ---> -7 b + 14 c = 0 so -7(2c) = -14 c c = anything at all In your linear algebra using Cramer&#...
*February 12, 2015*

**Physics**

You must know the acceleration A of the shuttle F = m A + m g
*February 12, 2015*

**physics**

work = change in potential energy = m g h No work is done in the horizontal motion because the force, gravity, is perpendicular to the direction of motion during horizontal displacement.
*February 12, 2015*

**math**

A = x y cost = 75 x + 60 y = 1750 60 A = x (1750 - 75 x) maximize 60 A = z z = 1750 x -75 x^2 75 x^2 -1750 x = -z complete square to find vertex o parabola x^2 - 23.3 x = -z/75 x^2 - 23.3 x + 11.7^2 = - z/75 + 136 (x -11.7)^2 = -(1/75)(z-10,200) x = length = 11.7 A = z/60 = ...
*February 12, 2015*

**Physical sciences**

v = 0 + a t 12 = a (5) a = 12/5 Is that the whole question? Surely they ask about the deceleration as well? d = Vi t + (1/2) a t^2 so 24 = 12 t + (1/2) a t^2 v = Vi + a t so 0 = 12 + a t
*February 12, 2015*

**algebra**

if b is base 8 b + b = 36 9 b = 36 b = 4 then 4 b = 16 so 16 , 16 and 4
*February 12, 2015*

**physics**

(1/2) m v^2 = m g h v = sqrt (2 g h) = sqrt(2*9.81*4.03) average speed = v/2 5.00 = (v/2) t t = 10/v
*February 12, 2015*

**Physics**

tension - T inward force = T cos 30 so T cos 30 = m v^2/.6 downward force = mg = T sin 30 = T/2 T = 2 m g so 2 m g = m v^2/.6 v^2 = 1.2 g if you want angular velocity v = omega r omega = v/.6
*February 12, 2015*

**Physics**

power = V^2/Req = 9.8 = 26^2/Req so Req = 69 ohms so R = 2 Req = 138 Ohms new Req: 1/Req = 1/138 + 1/276 Req = 92 Ohms power = 26^2/92 = 7.35 Watts
*February 12, 2015*

**physics**

correct
*February 12, 2015*

**GEO**

7.5 * 5*10^4 cm (1 km/10^5 cm) = 37.5 * 10^-1 = 3.75 km
*February 11, 2015*

**Physics**

If there were a potential difference current would flow. i = V/R where V is the potential difference and R is the resistance In a perfect conductor the resistance is zero and and V ( potential difference) would lead to infinite current to wipe out the potential difference. ...
*February 11, 2015*

**math(5th grade)**

.375 = 3/8 (3/8)120 = 3*15 = 45
*February 11, 2015*

**physics**

m1 = 3 m2 = 4 F = m1 a1 = 3 a1 F = m2 a2 = 4 a2 so 3 a1 = 4 a2 3 * 6 = 4 * a2 a2 = 18/4 = 9/2 = 4.5 m/s^2
*February 11, 2015*

**physics**

40 = (1/2)(9.81) t^2 t = 2.86 seconds v = g t = 9.81 * 2.86
*February 11, 2015*

**physics**

13400 cm (1.72*10^-6) ohm cm /2.07*10^-2 cm^2 = [(1.34)(1.72)/(2.07)] * 10^(4-6+2) = 1.11 Ohms
*February 11, 2015*

**physics**

multiply
*February 11, 2015*

**MATH**

18 qt * 1 gal/4 qt = 2.5 gal 7 half gal * 1 gal/2 half gal = 3.5 gal 2.5 + 3.5 = 6 gal
*February 5, 2015*

**Math Ms Sue please help me**

We can not see your picture so have no idea how to help.
*February 5, 2015*

**physic**

420 rev/min = 420 * 2 pi /60 = 44 radians/second 120 rpm = 12.6 rad/s alpha = (12.6 - 44 ) /4 = -7.86 radians/s^2 (part A) angle = initial omega t + (1/2) alpha t^2 angle = 44 (4) - (1/2)(7.86)(16) = 113 radians 113/2pi = 18 revolutions 18 * 2 pi r =18 *2 pi * .2 = 22.6 cm but...
*February 5, 2015*

**physics**

d = u t for car d = 20.1 t d = (1/2) a t^2 for cruiser d = (1/2) 2.65 t^2 = 1.325 t^2 so 1.325 t^2 - 20.1 t = 0 t (1.325 t - 20.1) = 0 they are together at t = 0 and again at t = 20.1/1.325 = 15.2 seconds
*February 5, 2015*

**physics**

v = Vi - 9.81 t at top v = 0 t = Vi/9.81 at top Vi = 20.1 sin 33.4 = 11.1 so t = 11.1/9.81 = 1.13 seconds at top how far horizontal in 1.13 seconds? u = 20.1 cos 33.4 = 16.8 m/s 16.8 m/s * 1.13 s = 19 meters
*February 5, 2015*

**algebra**

2.5 pounds/month is a constant slope of weight as a function of age. Therefore we are dealing with a straight line, linear function. (eventually it will hopefully turn exponential as it approaches full grown weight but that is a later problem :) six weeks = 1.5 months weight...
*February 5, 2015*

**chemistry**

They are liquid.
*February 5, 2015*

**Math**

You are welcome.
*February 5, 2015*

**Math**

7/8 = .875 14/14 = 1 1 4/9 = 1.444444444...... 3.2 = 1.5 which is the winner
*February 5, 2015*

**math**

Hey, you are supposed to know how to solve simultaneous linear equations or would not have been given this problem: http://www.jiskha.com/display.cgi?id=1423159248#1423159248.1423161824
*February 5, 2015*

**math**

2.4 * 2.8 * 3 = 20.16 m^3 1 m^3 = 1000 liters so V tank = 20,160 liters we have 3,600 liters so must deliver 16,560 liters 16,560 liters / .5 liters/s = 33,120 seconds /3600 = 9.2 hours 9 hours and 12 minutes
*February 5, 2015*