Saturday

February 25, 2017
Total # Posts: 2,430

**math**

3(k-4.8)=0.7(k-6.9) 3*k-3*4.8=0.7*k-0.7*6.9 3k - 14.4 = 0.7k - 4.83 Subtracting 0.7k from each side: 3k -0.7k - 14.4 = 0.7k - 0.7k - 4.83 2.3k - 14.4 = -4.83 Adding 14.4 to each side 2.3k = 9.57 Dividing each side by 2.3: k = 4.16

*December 5, 2012*

**physics**

The bullet goes from rest to a speed of 710 m/s in 2.36 * 10^-3 s v = a*t where v is the speed, a is the acceleration, and t is time 710 = a * 2.36*10^-3 Solve for a Force = m*a where m is mass

*December 5, 2012*

**math**

The total number of answers recorded is 35+35+30 = 100 3 of these answers belong to 1 person: At this point in the problem, person count = 1 answer count = 100-3 - 97 6 used buses as well as their own cars. One of these persons would be the person who used all three; so 5 used...

*December 5, 2012*

**Math**

9 use shampoos A and C. This set of 9 also includes people who would use B. 5 people use all three 9 - 5 = 4

*December 5, 2012*

**math**

140 students owned iPhones; of these 50 also owned cars; 140 - 50 = 90 90 students own only an iphone 60 owned cars; of these 50 also own a car; 60-50 = 10; 10 students own ONLY a car The number of student who own either a car or an iphone, but not both is 90 + 10 = 100 The ...

*December 5, 2012*

**math**

First draw a picture. Split the isosceles triangle down the middle of triangle, bisecting the angle x. Now you have divided the isosceles triangle into two right angled triangles, each with area of 1/2 height * base. So the area of the isosceles is the sum of both of these ...

*December 5, 2012*

**9th grade math**

Start putting all the equations into the same form y = a*x + b A: -x+y=9; y =x + 9 x-y=9; x = 9 + y; y =x-9 These two are not the same B: -x+y=9; y = 9+x x-y= -9; x = -9+y; y = x+9 These two are the same C: -x+y=9; y = 9+x -x-y=9; -y = 9+x; y = -x -9 These two are not the same...

*December 5, 2012*

**Physics**

torque = F*r = I*alpha where F = force, r = radius, I = moment of inertia, and alpha is angular acceleration. a) For a cylinder I = 1/2*m*r^2, where m is mass b) F*r = 1/2*m*r^2*alpha Substitute values from the problem to find m c) omega = alpha*t where omega is angular velocity

*December 5, 2012*

**PHYSICS**

y = A sin(30t - 0.041x) y = -Asin(0.041x - 30t) this is of the form y = A*sin(k*x - omega*t) k = 0.041 omega = 30 where omega = 2*pi*f; 30 = 2*pi*f; where f is frequency; use this to solve for answer in a) b) k = 2*pi / lambda, where lambda is wavelength; c) the speed of the ...

*December 5, 2012*

**physics**

omega = (k/m)^0.5 T = 2*pi/omega where T is period, omega angular acceleration

*December 5, 2012*

**physics**

Consider the mass on a spring in the figure below. If the spring constant is k = 28 N/m and the mass is m = 2.1 kg, what is the period? _____ s Any help will be appreciated.Thank you.

*December 5, 2012*

**Physics**

A large suitcase full of gold sits at the bottom of a lake. A team of treasure hunters uses a crane to recover the suitcase and finds that a force of 2.6 105 N is required to lift the suitcase to the surface. What is the volume of the suitcase? _____m^3

*December 5, 2012*

**Physics 1**

The antinodes of a wave would be a crest; the node of a wave would be where the wave is at 0; The separation of nodes and antinodes are 1/4 wavelength; the wavelength is 0.052*4

*December 5, 2012*

**Physics 1**

When all the mechanical energy is kinetic energy, the energy is 1/2*m*v^2 = 1/2*m*omega^2*r^2 where m is the mass, r is the radius, and omega is the angular velocity; For a pendulum, the angular velocity is given by omega = (g/r)^0.5

*December 5, 2012*

**Physics 1**

T = 2*pi/omega where T is the period 0.14 = 2*pi/omega Solve for omega omega = (k/m)^0.5 where k is the spring constant; use algebra to solve for k

*December 5, 2012*

**Algebra I HELP!**

It looks like the charged line is the Time(min)*(1 dollar/min) + $3

*December 5, 2012*

**Physics**

The initial heat of the water and can is 600*Cw*25 + 55*0.1*25 + x*Cw*65 The final heat of the water and can is (600+x)*Cw*31 + 55*0.1*31 Set the inital and final heat equal to each other, and solve for x; You will have to look up the specific heat of water (Cw), it should be ...

*December 5, 2012*

**physics**

Tf = (9/5)*Tc+32 where Tf is the temperature in Fahrenheit, Tc is the temperature in degrees Celsius

*December 5, 2012*

**physics**

A 5kg mass was lifted 365cm, how much work was done against gravity?

*December 4, 2012*

**Physics**

Use conservation of momentum, and conservation of kinetic energy for an elastic collision. m*30 + m*-20 = m*v1 + m*v2 where v1 is the final speed of the first ball, v2 is the final speed of the second ball Simplifying the equation (dividing both sides by m, adding like terms) ...

*December 2, 2012*

**physics**

In an elastic collision, both momentum and kinetic energy are conserved. Conservation of momentum m*3 = m*vA + 2m*vB or 3 = vA + 2*VB where vA is the speed of A, and vB is the speed of B Conservation of kinetic energy: 1/2*m*3^2 = 1/2*m*vA^2 + 1/2*2*m*vB^2 9 = vA^2 + 2*vB^2 ...

*December 2, 2012*

**Physics**

E = ke*|Q|/r^2 where ke is Coulomb's constant, Q is the charge, r is the distance from the charge E = (ke*10^-4)/0.3^2

*December 2, 2012*

**Math**

A black and red card are independent because you cannot draw a black card that is also a red card. A black card and a queen are not independent because you can draw a card that is both black and a queen. A face card and a queen are not independent because you can draw a card ...

*December 2, 2012*

**Phusics**

The kinetic energy of an object is 1/2*m*v^2, so an object moving in the y direction will have a speed, and therefore also kinetic energy (KE) If you apply a force in the Y direction the velocity will not necessarily increase, only if the object experiences a net force. For ...

*December 2, 2012*

**Physics URGENT!!!**

fo=(1/(1±vs/v))fs Where the plus sign is negative if the source is approaching the observer and positive if the source is moving away from the observer. fo is frequency of the observer fs is the frequency of the source vs is the speed of the source v is the speed of ...

*December 2, 2012*

**Physics**

Assume that the boxcars all have the same mass. Use conservation of momentum: 2*m*vi = 3*m*vf where m is the mass of one boxcar, vi is the initial speed, vf is the final speed. 2*m*4 = 3*m*vf vf = 8/3 Initial kinetic energy is ki 1/2*(2*m)*vi^2 = m*4^2 = 16*m Final kinetic ...

*December 2, 2012*

**physics**

First, find the equations that are pertinent to the problem. F(spring) = -k*x where F(spring) is the force on a spring, k is the spring constant, and x is the displacement. w = (k/m)^1/2 where w is the angular acceleration, m is the mass of the spring T = 2*PI/w where T is the...

*December 2, 2012*

**history**

Do you think that the Korean War was merely a civil war in which the United States supported one side, or should it be considered an international war in which the United States used the United Nations to further its anticommunist policie? Can someone please help me thank you!

*November 30, 2012*

**PreCalculus**

Suppose that a polynomial function of degree 5 with rational coefficients has -2, 5, and 3 - I as zeros. Find the other zeros.

*November 29, 2012*

**algebra**

x*((1 + .07/12)^(49*12)) = 500,000 Solve for x

*November 29, 2012*

**physics**

y = y0 + v0*t - 1/2*g*t^2 where y0 is the initial height = 0, v0 is the initial speed, and g is the acceleration due to gravity, t is time, and y is the vertical position. The ball reaches it's maximum height when dy/dt = 0 = v0 - g*t and y = 5, so 5 = v0*t - 1/2*g*t^2 Use...

*November 29, 2012*

**Linear equation**

Start making a table of points. For y=4, for any value of x, y = 4 x y -4 4 -3 4 -2 4 -1 4 0 4 1 4 2 4 3 4 The graph will be a horizontal line through (0, 4)

*November 29, 2012*

**Algebra2**

Get all equations in the form y = m*x + b. Once it's in this form, m is the slope, b is the y intercept. 1. 2x-3y=6 2x - 6 = 3y y = 2/3x - 2 The slope is 2/3, the y intercept is -2 2. y=-2x y = -2x + 0 The slope is -2, the y-intercept is 0. 3. y = 3 y = 0*x + 3 The slope ...

*November 29, 2012*

**pre algebra**

-5 x 1 x 11 x 4 Look for multiplying numbers together that end up being multiples of 10; -5*4 = -20, so using the associative property -5 x 1 x 11 x 4 = (-5 x 1 x 11) x 4 Using the commutative property: = 4*(-5 x 1 x 11) = 4*-5 x 1 x 11 = (4*-5) x (1 x 11) = -20 * 11 Factoring...

*November 28, 2012*

**Physics**

For an elastic collision, both kinetic energy and momentum are conserved. Conservation of momentum m(He)*v(He,initial) = m(He)*v(He,final) + m(H)*v(H) where m(He) is the mass of the Helium, v(He, inital) is the initial speed of the Helium , etc. . . Conservation of kinetic ...

*November 28, 2012*

**Physics**

.92^3

*November 28, 2012*

**Physics**

Set the force of gravity equal to the force of the centripetal acceleration: G*m*M/r^2 = m*v^2/r r is radius of orbit, G is gravitational constant, M is mass of earth, m is mass of satellite (which cancels out of both equations), v is the speed of the orbit

*November 28, 2012*

**College Algebra**

h = 0.62*w where h is height, w is width P = 2*h + 2*w = 2 = 2*0.62*w + 2*w solve for w, then use first equation to solve for h

*November 28, 2012*

**5th math**

1: 2 2: 5 3: 3 4: 5 5: 4 6: 5 You'll notice that all the even numbered terms in the sequence(2nd term, 4th term, 6th term, etc.) are 5 The odd numbered terms in the sequence each increase by 1. So the next three terms should be 5, 5, 6

*November 28, 2012*

**Probabilty**

For each coin toss, the probability of x=1 is 0.4. The mean value of X for n tries is : (0.4(1)*n)/n = 0.4

*November 28, 2012*

**Calculus**

dy/dx = (x*y)^0.5 Integrate and solve for y, find the constant by making sure it passes through (1/2)

*November 27, 2012*

**college algebra**

log10(7^x) = log10(8) Using log rules (log(a^b) = b*log(a)) x*log10(7) = log10(8) x*.845 = .903 = log(8)/log(7) x = 1.068 to 3 decimals

*November 27, 2012*

**trig**

Should this be Q IV (quadrant 4) tan-1(-4/3) = -53.13 degrees (-53.13 degrees = 360 + -53.13 = 306.87, is in quadrant 4) Evaluate with your calculator cos(2*306.87)

*November 27, 2012*

**calculus**

Use some trig identities: tan(-x) = tan(x) csc(x) = 1/sin(x) tan(x) = sin(x)/cos(x) tan(-x)*csc(x) = tan(x)*(1/sin(x) = (sin(x)/cos(x))*(1/sin(x) = 1/cos(x) = sec(x)

*November 27, 2012*

**calculus**

cos(theta) = 3/5 Use your calculator: cos-1(3/5) = theta = 53.13 degrees This is the value that your calculator gives, and it is in quadrant; To find the value theta corresponding to quadrant 4, notice the symmetry in a graph of cos x, which is that cos(x), cos(x) = cos(360 - ...

*November 27, 2012*

**math**

The slope m of a line passing through two points (x1, y1), (x2, y2) is given by m = (y2-y1)/(x2-x1) m = (-5/6 - -5/4) / (-3-2/3) = (5/12) / (-11/3) = -15/132 = -5/44 The equation for a straight line is of the form y = m*x + b where m is the slope and b is the y-intercept. So ...

*November 27, 2012*

**Physics**

Use conservation of momentum Initial momentum: The momentum of inertia of the objects the students is m*r^2 (3.0 + 3.4*1^2 + 3.4*1^2)*wi = (3.0 + 3.4*.45^2 + 3.4*.45^2)*wf where wi = 0.75 is the initial angular momentum, and wf is the final angular momentum. Solve for wf b) ...

*November 27, 2012*

**college algebra, Please help!!**

log(1.9)= log(a^6) log(1.9) = 6*log(a) log(a) = (log(1.9))/6

*November 27, 2012*

**calculus**

The distance from a point on the line from the origin is ((y-0)^2 + (x-0)^2)^0.5 = (x^2+y^2)^.5 = (x^2 +(x+4)^0.5) evaluate d/dx((x^2 +(x+4)^0.5)) = 0 This is the x value of the point closest to the origin, plug x into y = sqrt(x+4) to find the y value of this point

*November 27, 2012*

**physics**

I'll choose to place the piano 1/4 way from the right end Fr= force right Fl=force left Fr+Fl-W-mg=0 where mg is the weight of the beam, W is the weight of the piano (The sum of the forces in the vertical direction is zero because nothing is moving) Then sum of the torques...

*November 27, 2012*

**math**

Use the pythagorean theorem 3.75^2 + 2.84^2 = d^2, where d is the diagonal. Solve for d.

*November 21, 2012*

**Maths - HELP PLZ**

Put into your graphing calculator the equation y = 3x^2 + 10x-8 Then describe the regions of x for which the y-values are greater than 0.

*November 21, 2012*

**Physics**

v = omega/k The wave equation is of the form D(x,t) = A*sin(k*x-omega*t) k = 5.36 omega = 6.71 solve for v, the wave speed

*November 21, 2012*

**Physics**

The wavelength, lamda is 4.48 m The frequency f is 13/5.97 v = lamda*f where v is the wave speed

*November 21, 2012*

**Physics**

Use conservation of momentum: m1*v1 = m2*v2 Where m1 and v1 are the mass and speed of the initial system, m2 and v2 are the mass and speed of the final system 10*v1 = (10+3990)*50

*November 21, 2012*

**Math Functions**

f(x)= 3x+2/2x+4 graph the function horizontal and vertical asymptotes. Show the table. I found the horizontal and vertical asymptotes, but im confused on how to do a table

*November 19, 2012*

**math 104**

From a survey of 100 college students, a marketing research company found that 50 students owned iPhones, 45 owned cars, and 35 owned both cars and iPhones.

*November 18, 2012*

**physics**

After the light passes through the first Polaroid, it's intensity is 1/2Io. Now the light is polarized After the second sheet, it is now 1/2I0*((cos(59))^2) After the third sheet it is 1/2I0*((cos(59))^2)*((cos(59))^2) . . Do this up to the 6th sheet, and divide by I0

*November 16, 2012*

**Probability**

1/3 He asks three person a question, and only one of them tells the truth. The probability of getting the truthful man to answer is 1/3

*November 16, 2012*

**Physics**

y = y0 + vy*t + 1/2*ay*t^2 Where y is the distance in the vertical direction, y0 is the initial y position, vy is the speed in the y direction, ay is the acceleration in the y direction, t is time. Choose a coordinate system so that y0 equals zero at the baseball player's ...

*November 15, 2012*

**Physics**

1 decibel = A*log(P/P0) = A*log(1.122) Where P0 is the initial pressure, P is the pressure 1 decibel = 0.05*A A = 20 L = 20*log(P/P0) 8 = 20*log(P/P0) Solve for P/P0

*November 15, 2012*

**physics PLEASE HELP**

The difference in decibels between the two is defined to be 10 * log (P2/P1) Where the log function is in base 10, and P2 and P1 are the power of the sources at r2 and r1 6.5 = 10*log(P2/P1) 0.65 = log(P2/P1) 10^0.65 = P2/P1 = 4.46 Power is proportional to the radius squared, ...

*November 15, 2012*

**Physics**

d1*V1 = d2*V2 where d1 and V1 are the density and volume of object 1; d1 and V2 are the density and volume of the fluid Then V2 = 0.14*V1 d1*V1 = d2*0.14*V1 d1 = d2*0.14 Look up the density of water at 0 degrees C (= d2). Solve for d1 b) d1*V1 = d2*V2 You know d1 from a. You ...

*November 15, 2012*

**Physics**

P(water) = P0 + d*g*h where P is the pressure of water, P0 is the atmospheric pressure of the air at the surface of the water, d is the density of water, g is the constant acceleration due to gravity, and h is the depth of the water beneath the surface 1000*P0 = P0 + 1025*9.8...

*November 15, 2012*

**chem**

A solution is prepared by dissolving 25 grams of sodium sulfate in enough water to give a total volume of 500. mL. The molar mass of sodium sulfate is 142 grams per mole. What is the molarity of the solution?

*November 14, 2012*

**finite math**

There are 4 aces in a deck of 52 cards. The probability of an ace being in any position in the deck is 4/52 = 1/13. The probability of an ace being in the 3rd position is 1/13

*November 13, 2012*

**Physics**

x = vx*t y = 0.95 - 1/2*g*t^2 where x is the displacement in the horizontal direction, y is the displacement in the vertical direction, and t is time, vx is the speed of the cart in the x direction, and g is the acceleration due to gravity = 9.8 At it's landing, x = 0.4, y...

*November 13, 2012*

**math**

Go through the numbers 1 through 100, cross out all the numbers that are divisible by 2 (except 2), then the numbers that are divisible by 3(except three), then the numbers that are divisible by 5 (4 should be crossed out because it was divisible by 2) Do this all the way up ...

*November 13, 2012*

**math**

The factors of 100 are 1, 2, 5, 10, 20, 25, 50, 100 8%

*November 13, 2012*

**math**

8x/y2*4y/7x

*November 12, 2012*

**physics**

The rotational energy of each astronaut is 1/2 * I * omega^2 where I is the moment of inertia, and omega is the angular speed. The moment inertia of the astronaut is m*r^2 r = 12.0 / 2 = 6 m v = 5 m/s = omega*r The total rotational energy is 1/2 * I * omega^2 + 1/2 * I * omega...

*November 11, 2012*

**Physics**

Set the centripetal acceleration to the acceleration of gravity v^2/r = g

*November 11, 2012*

**physics**

F*r = I*alpha where F is the force, r is the radius, I is the moment of inertia, and alpha is the radial acceleration 470*0.370 = I * 0.8

*November 11, 2012*

**math**

5 out of 10 columns are multiples of 2, so 50% of all numbers are multiples of 2 2 out of 10 columns are multiples of 5, so 20% of all numbers are multiples of 5. The % of the numbers that are multiples of both 2 and 5 us 50% * 20% = 10%

*November 11, 2012*

**calculus**

Imagine what is happening from (-infinity < x < infinity) 1). from -infinity to x = -2, the graph is going up, then reaches a maximum at x = -2 2). From x = -2 to x = 1, the graph is going down to the minimum at x = 1 3). From x = 1 to x = 6, the graph goes up again to ...

*November 11, 2012*

**Physics**

You have two components of acceleration: a(centripetal) = v^2/r, which is the centripetal acceleration directed inward towards the center of the circle. dtheta/dt = omega = 2*a*t v = omega*r The second component of acceleration is the tangential acceleration, a(tangential) = (...

*November 11, 2012*

**physical science**

1/p + 1/q = 1/f M = -q/p where p is the distance of the object from the lens, q is the distance of the image from the lens, M is the magnification of the object. If M is positive the image is virtual and inverted; if M is negative the image is real and upright (erect). f is ...

*November 10, 2012*

**Algebra**

fc + (11-4)*b = fc + 7*b = 33 fc + (19-4)*b = fc + 15*b = 55 where fc is the fixed charge of the first 4 bushels, and b is the price per bushel of each additional bushel over 4 Use algebra to solve these two equations for b and fc: fc + 7*b = 33 fc + 15*b = 55

*November 10, 2012*

**algebra**

For every unit of increase in x, there is a 2 unit increase in y: k = 2 y = 2*x - 3

*November 10, 2012*

**science**

(p+q)^2 = 1 30% of the population have tt: q^2 = 0.3 p^2 + 2*p*(0.3^0.5) + 0.3 = 1 Solve for p p^2 is predicted frequency of TT 2*p*q is predicted frequency of Tt q^2 is predicted frequency of tt

*November 10, 2012*

**Physics**

F - csf*N = 0 N - m*g = 0 where F is the force, csf is the coefficient of static friction, N is the normal force, m is the mass of the cabinet, and g is the gravitational constant.

*November 10, 2012*

**Physics**

a) diameter = 2*radius = 0.15 m; radius = 0.15/2 area = pi*radius^2 b)Work = Force*distance = 160*0.15

*November 10, 2012*

**probability**

5*4 (color1, style1), (color1, style2), (color1, style3), (color1, style4), (color2, style1) . . .

*November 10, 2012*

**Science**

Looks good to me

*November 10, 2012*

**Physics**

a) The center of mass of the can is halfway up; the center of mass of the soda in the can is also halfway up when the can is full of soda, so the center of mass is (0.135*(12.4/2) + 1.25*(12.4/2))/(0.135+1.25) b) After the can loses all the soda, the center of mass is the ...

*November 9, 2012*

**Physics or Math**

The torque is about the point (-1.3, 2.4), so treat this as your origin,. . . This makes the r vector (4.3, -2.4, 0)

*November 9, 2012*

**Physics**

Use conservation of momentum: (65+0.18)*2.47 = .18*24.3 + 65*vf where vf is final speed of the ice skater b).Again, use conservation of momentum: 0.18*24.3 = (62+0.18)*vf

*November 9, 2012*

**Physics**

sum(F) = m*a where sum(F) is the sum of the forces, m is mass, and a is acceleration: 30 - 20 = 50*a

*November 9, 2012*

**Physics**

400 = 2*a(cb) where a(cb) is acceleration of the cannon ball 400 = 500*a(c) where a(c) is acceleration of the cannon

*November 9, 2012*

**Physics**

F = m*a where F = force, m is mass, and a is acceleration 25 = m * 5

*November 9, 2012*

**college algebra, Please help!!**

A. is f(-2) = 9? if it is, then the point (-2,9) is on the graph. Otherwise, it's not on the graph B.Plug 2 into f(x) f(2) = 2 * (2^2) - 2 - 1 The points on this graph are (2, f(2)) C. Solve -1 = 2*x^2-x-1 You should find two solutions for x. D. The domain of f is the ...

*November 9, 2012*

**Physics**

For an elastic collision, both momentum and kinetic energy are conserved. m1 = mass of colliding ball m2 = mass of ball initially at rest v1i = initial speed of colliding ball v1f = final speed of colliding ball v2i = initial speed of at rest ball = 0 v2f = final speed of at ...

*November 9, 2012*

**math**

I say c 127.1 / (127.1+32.1) = %Cu 32.1 / (127.1 += 32.1) = %S

*November 9, 2012*

**physical science**

F*d = W Where F is force, d is distance moved, and W is work

*November 8, 2012*

**math**

$3.96 = 396 cents 396 cents / 17 ounces is price in cents/ounces

*November 8, 2012*

**math**

8:9

*November 8, 2012*

**Science**

Look up the speed of sound, then multiply this number by 6 s.

*November 8, 2012*

**Physical Science**

v = f*lambda where v is the speed of sound, f is the frequency, and lambda is the wavelength

*November 8, 2012*

**physics**

For an elastic collision, both momentum and kinetic energy are conserved. Conservation of momentum: m1*v1 + m2*v2 = m1*v1f + m2*v2f where m1 and m2 are the mass of the car and truck, v1 and v2 are the initial speeds of mass 1 and mass 2, and v1f and v2f are the final speed of ...

*November 8, 2012*