Sunday

April 19, 2015

April 19, 2015

Total # Posts: 536

**Physics**

a 475 kg pre-stressed concrete beam is to be raised 10.0 m in 24.0 s. how many kw of power is needed to for the job
*April 2, 2015*

**physics**

Show that the kinetic energy of two particles with mass m1 and m2 split into the energy of the centre of mass and the kinetic energy of relative motion.
*March 9, 2015*

**physics**

A car covers half a distance at a velocity of 80km/h and the other half at 60km/h,what is the average velocity of the car?
*March 9, 2015*

**English LAST 1. (:**

It's about MLk I Have A Dream speech. Why does King use the rhetorical technique of parallel structure in his speech? A)to show that he is aware of the time that has passed B)to show that others are not aware of the time that has passed C)to show that two or more ideas ...
*February 3, 2015*

**English **One Question****

thank you :-)
*February 3, 2015*

**English **One Question****

In a sense we have come to our nation's capital to cash a check. When the architects of our republic wrote the magnificent words of the Constitution and the Declaration of Independence, they were signing a promissory note to which every American was to fall heir. This note...
*February 3, 2015*

**algebra**

This is similar to what I just answered earlier. x = total cost y= # of motors bought 150 = x*y solving for y: 150/y= x <--- (1) now we know: 150=(x-2)*(1+y) <--- (2) substitute using (2) and (1) we get : 150=((150/y)-5)*(1+y) 30 = y^2+y y^2+y -30= 0 (y+6)(y-5)=0 y = -6...
*November 6, 2014*

**algebra**

Sorry, made an error. once you complete the square: (y+10)^2 = 3600 solving for y gives you 50 so 50 calculators. you could also used the quadratic formula to solve for y and get the same answer.
*November 6, 2014*

**algebra**

x=cost of calculator y=number of calculators 350=(x-2)*(20+y) <-- equation 1 we know that total cost = cost per calc * number of calc bought 350 = x*y so 350/y = x <-- equation 2 we can substitute x from equation 2 into equation 1 350=((350/y)-2)*(20+y) solving this you ...
*November 6, 2014*

**algebra**

You will have two roots (two answers).
*November 6, 2014*

**algebra**

reciprocal means 1 over the number x + 1/x = 29/10 solve for x to get your number
*November 6, 2014*

**Physics**

Momentum formula: p=mv where p=momentum m = mass v= velocity p/m = v once you solve for v now apply: v^2=v_i + 2*g*h v=what you got from momentum v_i = starting speed = 0 g= 9.81 h=?????
*November 5, 2014*

**Math**

Beth's time = 7.8 seconds Amy = 7.8 -2.5 = ???
*November 5, 2014*

**physics**

conservation of momentum.. (1/2)*m*v = (1/2)*m2*v2 m = 3 v = ?? <-- speed of spitball m2 = 40 + 3 = 43 (added the sum because assuming that the spitball sticks to the carton, thats the total mass) v2 = .3 solve for v
*November 5, 2014*

**physics**

Conservation of momentum problem since system is a rest before firing 0 = m1*v1 + m2*v2 everything is given in problem besides v1 So solve for v1
*November 5, 2014*

**physics**

Another conservation of momentum problem m1*u1+m2*u2 = m1*v1+m2*v2 m1 = 250 = .25kg u1 = 1.5 m2 = 4 v1=.89 solve v2
*November 5, 2014*

**Math**

Is there a figure that comes with this?
*November 5, 2014*

**math Help!!!!!!**

Area of a square: A=s^2 You are given the area so: 160=s^2 solve for s So I agree with your answer.
*November 5, 2014*

**physics**

F=ma where a=9.81m/s^2 (gravity) solve for m now use the formula: (1/2)m*v^2 + m*g*h = m*g*h2+(1/2)*m*v2^2 m=755 v=0 h=10 (starting height) h2=0 (final height) v2 = ?? this is what we're trying to find. try to solve for v2 given the equation.
*November 5, 2014*

**physics**

For constant velocity: F = μk*W
*November 5, 2014*

**PHYSICS**

I'm guessing it depends on the direction of the magnitude. if both are positive |3+4|=7 if one is negative |-3+4|=1 if the other is negative |3-4|=1 So considering all the possibilities, it can't be anything besides 7 and 1
*November 4, 2014*

**Physics**

Could you post the whole question? From what's given, there are lot of questions you can ask from that statement.
*November 4, 2014*

**algebra**

Given: 96 calories in a 3/4 cup serving We need to find out how many calories in 5 cup. Solution: Set up a equation for the ratio of calories to cup serving. 96/(3/4) = x/5 Solve for x to get your answer
*November 4, 2014*

**Market Research**

Let N 6 and n 3. For purpose of studying sampling distributions, assume that all population values are known. Specically, y1 98, y2 102, y3 154, y4 133, y5 190, and y6 175. We are interested in yU, the population mean. Two ...
*November 3, 2014*

**math**

Ah, that is true! at 12 minutes he did climb 12 meters and it took him another .45 seconds to climb the rest. Wow, I completely neglected some stuff here. Thanks for clarifying Steve!
*November 3, 2014*

**math**

Hmm… The wording in this problem is a little tricky to me, so I'm assuming that its an alternating pattern (poor monkey). For the first minute the monkey is at 4 meters For the second minute monkey is at 2 meters ( because he slips down) So basically every 2 minutes, ...
*November 3, 2014*

**any math tutor want to check my work, not feeling too confident**

I guess this is a calculus problem. When I drew this out, I got a right triangle x = length the foot is from the wall = 4 6 = length of ladder = hypothenuse h = unknown height of wall dx/dt = .5 m/sec use pythag theorem to find h: x^2 + h^2 = 6^2 4^2+h^2 = 6^2 h =4.47 Now find...
*November 3, 2014*

**physics**

w w w.physicsclassroom. com/class/1DKin/Lesson-1/Scalars-and-Vectors
*November 3, 2014*

**physics**

First break your vector up into x and y components. Since its angled at 30 degrees with the horizontal, the x component with have cosine in it and sin for the y component. x component = 170cos30 y component = 170sin30 where y is your vertical component.
*November 3, 2014*

**maths**

Number of periods = 20 Years * 2 (periods per year) = 40 PV= $1600 i/2 = 13.5%/2 = 0.0675 FV = ? = PV * (1 + i/2)^N = 1600 * (1 + 0.0675)^40 = $21,819.02
*November 3, 2014*

**Solving inequalities**

g + 3 > 6 move 3 to right side g > 3
*October 31, 2014*

**physics**

Did you draw the free body diagram first?
*October 30, 2014*

**Algebra**

Look at the original equation: 6x^3 + 12x^2 + 4x + 8 You can factor a 2 out of the whole equation: 2(3x^3 + 6x^2 + 2x + 4) Now try to factor inside of the parenthesis: How I factored it was I just did trial and error lol, I just takes some practice, when once you get good at ...
*October 30, 2014*

**math**

Total number of socks = 6+4 = 10 For the first pull: There are 6 purple socks out of 10 total socks 6/10 At his second pull, lets assume that he luckily pulled a purple sock out There are now 9 socks total because he pulled one out, and 5 purple socks left because we assumed ...
*October 30, 2014*

**TYPO sorry**

m = (-2-(-5)5)/(6-1) should be m = (-2-(-5))/(6-1) m = 3/5
*October 30, 2014*

**ALgebra**

Also, for the first question the answer is y = 0*x - 3 I think you just made a typo
*October 30, 2014*

**ALgebra**

To find the equation for a line we use the formula Y = mx+b where m = the slope where b = the intercept So you are given two points (1,5), (6,-2) You first need to find the slope of that line: m = (y2-y1)/(x2-x1) m = (-2-(-5)5)/(6-1) m = 3/5 <---- slope now that you have ...
*October 30, 2014*

**Hydraulic Physics**

20/25 = F/50 F = (20/25)*50 F= 40 N
*October 29, 2014*

**Hydraulic Physics**

No need for gravity. F1/Area1 = F2/AREA2 Solver for F1
*October 29, 2014*

**Dudas**

They key thing you need to know is what the center of mass formula is. Center of mass: (m1*x1+m2*x2)/(m1+m2) So at initial center of mass: (86*9+55*2)/(86+55) = 6.27 m So now do apply the same equation when they switch position: (55*9+86*2)/(86+55) = 4.73 m So now find the ...
*October 29, 2014*

**Physics**

How did you start this problem?
*October 29, 2014*

**Physics**

Just a quick question… Did this problem come with a figure? I can't tell if those angles are along the horizontal or vertical.
*October 28, 2014*

**physics**

Veocity = distance / time You are given a distance of 40m and time of 1.9s
*October 28, 2014*

**physics**

When doing these types of physic problems or actually any physics problem, write down what's given. m=57.5 kg v_f= 58.9 m/s v_i = 0 (because it was a rest, not moving) t = 14.4 s g=9.81 m/s^2 The apparent weight is: W = F + m*g F=ma Everything is given to us in the problem...
*October 28, 2014*

**Algebra**

I almost agree with Aaliyah. Expressions do not need an equal sign so you can just write: 2m+7 but everything else that Aaliyah has posted is on point.
*October 27, 2014*

**math**

Set this up as a system of equation then solve: x = chalk y = stapler x+2y = 10 <--- equation 1 3x+2y = 18 <---- equation 2 Now, there are many methods when solving systems of equation, but I would use substitution method for this problem. Look at the first equation: x+...
*October 27, 2014*

**Math**

Actually after reading the problem, I think I rounded wrong. 338700 should be the correct answer.
*October 27, 2014*

**Math**

Set up an equation then solve: 320000 = x - x*(.055) where x is the amount they must sell their house for minus the 5.5 interest rate and still maintain 320000 x = 338624 But it says to round to the nearest $100, so x = 338600
*October 27, 2014*

**Physics**

Whoops, I think my units are off because since k is measured in N/m I need to convert cm to m Answer should be .03 Joules
*October 27, 2014*

**Physics**

Potential Energy of the compressed string at x=3.0cm: W = (1/2)*k*x^2 where k = spring constant = 15 N/m x = distance = 3.0 cm W = (1/2)*15*3^2 W = 67.5 Total work: W_t = (1/2)*k*x^2 where x = 4+3 = 7 W_t= (1/2)*15*7^2 W_t = 367.5 W_t - W = 367.5 - 67.5 Work needed for the ...
*October 27, 2014*

**math**

For the first problem just use a calculator to convert everything into decimals. a= 3.5 b = sqrt(15) =3.87 c = sqrt(1/16) = .25 d = 26/100 = .26 It's clear after converting everything, that choice b is the greatest Numer 2: Irrational numbers are numbers that cannot be ...
*October 27, 2014*

**Math**

For everyone 1 goat, there are 4 sheep. 50*4 = 200 200 sheep
*October 27, 2014*

**Math**

Set up an equation: (1/4)x = (2/3)*60 Solve for x to get how much Peter has x = 160 160 + 60 = 220
*October 27, 2014*

**Physcis**

There's a formula for this! R = R_o * A^(1/3) R_o =1.3*10^-15 m A = nucleon number which in your case is 85 R = (1.3*10^-15)* 85^(1/3)
*October 27, 2014*

**Math**

a = (max-min)/2 d=(max+min)/2 is period given in the problem?
*October 27, 2014*

**physics**

If you want to check your answer, I got 283.19N
*October 27, 2014*

**physics**

I wish i could post a link of my FBD here, but the website won't allow any links to be posted. It's really hard to explain on here if you can't see a free body diagram. Could you show me how you started it and maybe I can try to follow what you're doing?
*October 27, 2014*

**physics**

John, first draw a free body diagram. then break each vectors up into x and y components Fx = 5.6cos75 - 3.8cos45 Fy = 5.6sin75 - 3.8sin45 Direction: tan^-1(Fy/Fx)
*October 26, 2014*

**algebra**

A(t)=3-2t^2+4^t just plug 2 in for t to get A(2) then plug 1 in for t to the given equation to get A(1) Then A(2) - A(1)
*October 26, 2014*

**Math**

Thats correct so far.
*October 26, 2014*

**Physics**

Part a) Assume that downward is positive for this problem. V=V_o + g*t V_o = 2.13 g=9.8 t=4.38 V=2.13 + (9.8*4.38) V = 45.1 m/s part b) x= V_o*t + (1/2)*g*t^2 x=(2.13*4.38)+(1/2)*9.81*4.38^2 x=103.43 note that the helicopter is going down at: x1=2.13*4.38 = 9.33 X = x - x1 X...
*October 26, 2014*

**algebra**

Wait Mr. Reiny, I think there is a typo. 3x^2+x-2=0 So there should be two roots x= -1 x = 2/3 And since the question is asking for "integer", I guess only -1 works since 2/3 is a fraction which is not an integer.
*October 22, 2014*

**algebra**

Equation: 3x^2 + 1*x = 2 I don't think that equation will factor, so you're going to have to use the quadratic formula to find what x is. 3x^2 + x - 2 = 0 I got x to be -1 and 2/3 Let me know if you got the same from applying the quadratic formula
*October 22, 2014*

**physics**

So it takes the blade .398s to move 90 degrees a full circle is 360 degrees 360/90 = 4 So time it takes to move around whole circle: T = .398*4 = 1.59s Velocity = Distance / time Distance in this case is the circumference of circle: C=2*pi*r where r is radius so C = 2*pi*(.352...
*October 22, 2014*

**Algebra**

First find the slope of the line through those coordinates. Slope formula: m = (y2-y1)/(x2-x1) m=(7-3)/(4-5) m=4/-1 m=-4 So the slope is -4 Now use the point slope formula: y-y1=m(x-x1) y-3 = -4(x-5) y-3=-4x+20 y=-4x+23 You will get the same result if you use the other ...
*October 22, 2014*

**math**

First you have to find how much each chairs cost 560/16 = 35 So each chair cost $35. 35 * 24= 840
*October 22, 2014*

**PHYSICS**

Part a) Moment of Ineria for a sphere (formula is different depending on the shape: I = (2/5)*m*r^2 I = (2/5)*14.5*.120^2 = .0835 Angular momentum = I * angular velocity .0835 * 6.15 = .51 kgm^2/s Part B) Kinetic energy = (1/2)*.0835*(6.15)^2 = 1.579 J
*October 22, 2014*

**physics**

Is that the whole question? I'm guessing to break that force up into x and y components Fx = 52.8cos18 Fy = 52.8sin18
*October 22, 2014*

**Math - Please Help Check My Answer**

The answer the student has is correct. c = -1/13 The correct answer is A The answer is negative.
*October 22, 2014*

**physics**

D = speed * time just make sure to convert your units. Give it a try!
*October 22, 2014*

**guidance**

Key word: NOT B.
*October 22, 2014*

**Physics**

oops tan^-1(368.85/190.5) = 62.68
*October 21, 2014*

**Physics**

hmm.. Vx= 220cos30 = 190.5 Vy = 110 s=-Vy*t + (1/2)*a*t^2 2800 = -110*t + (1/2)*(9.81)*t^2 use quadratic equation to solve for t t=37.6s v=g*t v=9.81 * 37.6 v=368.85 tan^-1(v/vx) tan^-1(368.85/110) = 73.39 See if that's correct..
*October 21, 2014*

**physics**

a=(vf-vi)/t vf=73.6 * (1/3600)*1609.34 = 32.9 m/s vi = 0 (at rest) a=32.9/7.68 = 4.28 m/s^2
*October 21, 2014*

**Precalculus**

a) radius of a circle a=pi*r^2 to write this as a function of r a("r")=pi*r^2 pug in what r is to find what a equals b) r(t) = 2.2t where you plug in what your t is to give you r try using what I gave you for part a and b to find out the rest. Post if you have ...
*October 21, 2014*

**Math**

weekly revenue rate = -500*1 Price decrease rate = -.45 Marginal Revenue = (-500*1)(-.45) = 225
*October 21, 2014*

**Math**

This type of problem involves a lot of trig idenities, I just looked them up.. Lets look at the LHS: csc^2(x)= 1/sin^2(x) cos^2(x) = 1-sin^2(x) Now we can say: csc^2(x)*cos^2(x) = (1-sin^2(x))/sin^2(x) now lets look at the RHS: csc^2(x) = 1/sin^2(x) and we can change that 1 to...
*October 20, 2014*

**physics**

Note that "r" and "g" cancels out when you put the coefficient of friction equal to each other for car A and car B
*October 20, 2014*

**physics**

Coefficient of friction is: u=v^2/(r*g) now lets apply this formula to the problem Set Car A = Car B and you get V_a^2/V_b^2 = u_a/u_b v_b=v_a*sqrt(u_b/u_a) (13.8)*sqrt(.843/.333) = 21.95 m/s
*October 20, 2014*

**TYPO**

Made a small typo.. Answer is y+9 =(7/8)*(x+2)
*October 20, 2014*

**Jay**

Yeah
*October 20, 2014*

**Jay**

Point slope form is y-y1 = m(x-x1) y-(-9) = (2/7)*(x-(-2)) y+9 =(2/7)*(x+2)
*October 20, 2014*

**Algebra**

You gotta make the graph, use those points.
*October 20, 2014*

**Algebra**

x coordinate can be all negative # and zero y can only be all negative # so make a t chart x=0,-1,-2,-3,-4,-5……. y=-1,-2,-3,-4,-5,-6….
*October 20, 2014*

**physics**

Was velocity given in the figure?
*October 20, 2014*

**MISTAKE**

Oops, I made a mistake.. (4500*.04)+(.1*x)=1000
*October 20, 2014*

**algebra**

Set this up as an equation. (4500*.1)+(.1*x)=1000 solve for x to get your answer.
*October 20, 2014*

**Algebra**

Well, rate of change = slope deltaY/deltX = slope deltaY = (y2-y1) deltaX =(x2-x1) For the year 1990-1992: deltaY = (55-52) = 3 deltaX =(1992-1990) = 2 3/2 = 1.5=slope So basically, you have to pick 2 years where deltaY > 3 deltaY <= 2 so the only years that meet those ...
*October 18, 2014*

**physics**

Sorry, I made an error… Vector A has both an x and y component: Fx=10cos25=9.06 Fy=10sin25=4.266 Magnitude of A = sqrt(9.06^2+4.266^2) = 10.0141 Vector B only has x components: Fx=8 Magnitude of B = 8 10.0141*8 = 80.112
*October 18, 2014*

**physics**

If I'm reading this correctly, the question wants you to find the magnitude of vector A and then multiply it to magnitude of vector B. If that's the case then… Vector A has both an x and y component: Fx=10cos25=9.06 Fy=10sin25=4.266 Magnitude of A = sqrt(9.06^2+4....
*October 18, 2014*

**Intermediate Algebra**

find the average of hours of homework completion. (6+9)/2 = 7.5 hours
*October 18, 2014*

**Trigonometry**

sin^-1(12/13) = 67.38 180-67.39 = 112.62 = A sin^-1(-7/25) = -16.26 = B Tan ( A - B) = ??? I think that's how you approach it.. someone verify please?
*October 15, 2014*

**math**

4+x+2=9
*October 15, 2014*

**math**

1/(8000*450) = 2.77*10^-7
*October 15, 2014*

**math**

Wait it's 2x+5=-c
*October 15, 2014*

**math**

I agree with your answer.
*October 15, 2014*

**Algebra 2 (PLEASE, HELP ME!)**

I think for part C: match a t chart for x and y for the light weight, x can be anything bigger than 200 and lower than 230 so x can be 200 all the way to 229 Now do the same for the heavy weight class then plot them. for part D: It's asking at what point the lines ...
*October 15, 2014*

**algebra**

Hmm.. lets start with the polynomial (x+13)(-x+12) = -x^2 - x + 156 part b) The discriminant is everything inside the square root of the quadratic formula 150= -x^2 - x + 156 -x^2-x+6 a=1 b=-1 c=6 so: b^2-4*a*c is the discriminant -1^2 - 4*-1* 6 = 25 and 25 > 0 part c) Just...
*October 15, 2014*

**Physics**

Kinetic energy + Potential Energy (1/2) *m*vf^2 + (1/2)*m*vi^2 = mgh m=mass but we we really don't need the mass to figure this problem out since we can factor it out of the equation Now isolate the vf vf = sqrt(2*g*h - vi^2) g=9.81 h=30 vi=45 vf=sqrt(2*9.81*30 - 45^2) vf=...
*October 15, 2014*

**Math**

97 rounded to nearest ten gives 100 97 rounded to nearest hundred gives 100 118 rounded to nearest ten gives 120 118 rounded to nearest hunted gives 100 5 rounds to nearest ten is 10 179 rounded to nearest ten gives 180 179 rounded to nearest hundred gives 200 5091 rounded to...
*October 15, 2014*