drwls

Newest questions and responses by drwls
  1. note to those with unanswered physics questions

    I have only been able to answer a few tonight. Preference is and will be given to questions in which evidence of work or thought is shown by the person posting the question.

    asked on October 21, 2010
  2. Briittany algebra question

    You should have posted this as a new question, not as a comment to someone else's thread. > Just combine "x" terms and combine constants on separate sides of the equation -x = 2 x = -2 x = -2

    asked on December 1, 2008
  3. calculus

    We are not going to do that work for you, but will be glad to help you. The unit sphere is the sphere with radius 1 centered in the origin. They give you the coordinates of a vector. Compute the dot product of the vector and the local surface area normal

    asked on August 5, 2007
  4. calc check

    If that is the y value of the center of mass, I don't know why the factor (1/2) is there I also don't agree with your calculation of the x value, which should be 1/(ln 2). I agree with you that the area is ln 2 find the center of mass of the region bounded

    asked on June 29, 2007
  5. math

    The "x intercept" is where y = 0, which is where the curve crosses the x axis. Solve y = x^2+ 2x- 8 = 0 You can write that as y = (x+4) (x-2) = 0 There are two places where y = 0. The factored equation tells you where they are. how would I find the

    asked on June 23, 2007
  6. math

    This is a "trial and error" type question. Algebra alone won't help you. First see what you could do buying 19 cow brains ($95) with $5 left. That could get you ten sheep brains ($1) and two pig brains ($4). The total would be only 31 total. Not enough. So

    asked on March 28, 2007
  7. Physics

    Equate the increase in potential energy at the higher elevation, M g H, to the decrease in kinetic energy. Make sure you include the kinetic energy of rotation, which is (1/2) I w^2. For a sphere of radius R, V = R w and I =(2/5) I R^2 Therefore

    asked on March 21, 2007
  8. Math

    Are you trying to solve for x, n or p? solve for n Show me how to work this problem. 2n = 4xp - 6 what is the problem? what grade r u in i am in 6 grade To get n all by itself, you need to divide by 2. But if you divide by 2 on the left, you have to divide

    asked on March 15, 2007
  9. Physics

    The stored potential energy in the trampoline at maximum compression, (1/2) k X^2, equals the gravitational potential energy at maximum height, M g H. (Kinetic energy is zero in both cases) X = 0.5 m g = 9.8 m/s^2 H = 2.5 m k = the spring constant. Solve

    asked on March 14, 2007
  10. math algebra

    Do you want the equation of a line through that point (1,2) with slope m = 4? Use the equation (y-y*) = m(x - x*) where x* and y* are the coordinates of the point the line has to pass through. (1,2)m=4

    asked on March 3, 2007
  11. Integral

    That's the same as the integral of sin^2 x dx. Use integration by parts. Let sin x = u and sin x dx = dv v = -cos x du = cos x dx The integral is u v - integral of v du = -sinx cosx + integral of cos^2 dx which can be rewritten integral of sin^2 x = -sinx

    asked on February 20, 2007
  12. math

    Derivatives are usually not taught in 5th grade. That is what your question is about: Rates of change. Complete the following statements with the correct words Note: Correct spelling is important. If s(t) is a distance (or height or position) function,

    asked on February 20, 2007
  13. Math (Calculus 121)

    The derivative tells you the slope at any point. df/dx = 8 x^3 - 12 x When x = 3, the slope is m = 8*27 - 36 = 180 and the equation of the tangent line is (y - 228) = 180*(x - 3) y = 180 x - 540 + 228 = 180 x - 312 wow, that was absolutely correct (i just

    asked on February 20, 2007
  14. math

    I believe Lance meant to write x = -5/18 I am wondering why you have two minus signs before the number 13. Two minuses make a plus, but usually they are not written that way. combine like terms -18x=5 solve for x x=5/18 what does x equal in...

    asked on January 18, 2007
  15. MATH

    24/(x+1) + 12/(4-x) = 14 Multiply both sides by (4-x)(x+1) 24(4-x) + 12(x+1) = 14(4-x)(x+1) 96 - 12x + 12 = -14(x^2 -3x -4) = -14x^2 +42 x +56 Combine terms and solve for x. sorry guys, here's another.I'm not the greatest at math but i do know some... The

    asked on January 18, 2007
  16. polynomials

    No to both questions. A polynomial is a sum of at least one integer power of x (or other unknown), each multiplied by a constant. '9' is simply a constant. 2^x is a power of 2, not a power of x. Is 9 a polynomial? Is 2^x a polynomial?

    asked on January 8, 2007
  17. Math

    (1 & 2) The first three points do not fall on a straight line, and there is no value of k that will make that happen. (4) To find the quadratic y = a x^2 + bx + c that passes through the first three points, solve simultaneously 1 = c 3 = 4a + 2b + c 6 = 16

    asked on December 25, 2006
  18. math,algebra

    They may want you to add the fractions and give the answer in forms of a fraction. in that case, you need to convert to common denominators before addineg. In that case 1/3 + 1/5 + 1/10 = (10 + 6 + 3) /30 = 19/30 5/6 - 3/5 = (25 - 18)/30 = 7/30 You answer

    asked on December 6, 2006
  19. Business Calculus

    The indefinite integral, or which call the "antiderivative", of f'(x)=6x-8x^3 is f(x) = 3x^2 - 2x^4 + C where C is any constant. Plug in x = 2 to that to see what C is. 3 = 3*4 - 2*16 + C Determine the antiderivative of the following function given the

    asked on December 4, 2006
  20. chemistry

    First of all, you need to know how many g of Mg actually reacted in the first reaction. You can determine this by determining the limiting reactant. The reaction is Mg + F2 -> MgF2 16.2 g of Mg is 16.2/24.32 = 0.666 moles 25.3 g of F2 is 25.3/38.0 = 0.666

    asked on August 30, 2005
  21. US HISTORY

    Bartolomeu Dias first rounded the Cape of Good Hope in 1488. Ten years later, Vasco da Gama also sailed around the Cape and continued to eastern Africa and India, claiming it for Portugal. Barthelomew Diaz

    asked on August 21, 2005
  22. Chemistry

    Some is released if the temperature is increased. Some O2 is always entering and leaving solution at the same time. You end up with an equilibrium between the two processes.

    asked on June 21, 2005
  1. Physics

    you're way smarter than I am.

    posted on October 16, 2016
  2. physics

    Use the inverse square law. You will need to look up the radius of the earth. It is about 3960 miles, as I recall. Square the ratio of the the distances to the center of the Earth at the top and the bottom of the building. Use that factor to compute the

    posted on June 14, 2016
  3. 4th grade math

    oh wow, crazy teacher huh? well it means to just multiply it

    posted on August 7, 2014
  4. math

    and she used the money for trip to africa

    posted on August 7, 2014
  5. Math

    Already answered. math - MathMate, Saturday, May 28, 2011 at 11:00pm Here we have 10 digits, of which the first one cannot be zero. If the three digits are distinct, there are 9 choices for the first digit, still 9 (including zero) for the second, and 8

    posted on August 23, 2013
  6. geometry

    Where is the road sign? What does Roseville have to d o with it?

    posted on August 23, 2013
  7. physical science

    A balance measures mass. A graduated cylinder measures the volume of liquids.

    posted on August 7, 2013
  8. Trig

    a. If you are only given the value of ƒÆ , you cannot deduce the value of the radius r. b. ƒÆ = pi - 0.213 rad = 2.929 rad csc ƒÆ = 4.739 c. cos ƒÆ = -0.977 d. cot ƒÆ = 1/(tan ƒÆ )= - (8/(ã3)

    posted on August 7, 2013
  9. Physics

    If T is the half life in days (1.6)/2.0 = (T/156)^(1/2) 0.8 = 0.08006 T^1/2 9.992 = T^1/2 T = 99.8 days The decay constant k is related to the half life by k = ln2/T

    posted on August 7, 2013
  10. Science

    Let the unit cube side be a. Its volume is a^3. Its area is 6a^2. The ratio is a/6. The inscribed sphere has a volume of (pi/6)a^3 and an area of pi*(a/2)^2*4 = pi a^2. The ratio is a/6. The inscribed right cylinder has a volume (pi/4)a^2*a = pi*a^3/4 and

    posted on August 5, 2013
  11. math

    N = 2^1 + 2^2! + 2^(1000!)!) The last number has no ending digits as small as 2 or 4 006 would be the last three digits of the complete number.

    posted on August 4, 2013
  12. physics

    Let the tension be T and the acceleration be a. Write separate free body diagram equations for the two weights T - 100g*sin37 = 100 a 70 g - T = 70 a 170 a = 9.82 g a = 0.058 m/s^2 Now solve for T

    posted on August 4, 2013
  13. Physics Normal force

    Yes. The "normal" force is the perpendicular component. There can be a parallel component as well.

    posted on August 3, 2013
  14. physics

    20 kg wt = 200 Newtons Force Component along ground = 200*cos 60 = 100 N Work = 20 * 100 = 200 J

    posted on August 2, 2013
  15. physics

    For the speed of the car (V), solve V^2/R = 2 m/s^2 V = sqrt400 = 20 m/s The centripetal force is (acceleration)*(Mass) = 2*2500 = 5000 N Centrifugal acceleration is the opposite of centripetal acceleration

    posted on August 2, 2013
  16. scince

    The time interval doesn't matter. F = (0.060 kg/s)(15 m/s) = 0.90 N

    posted on July 27, 2013
  17. iinterpersonal comminication skills

    I agree

    posted on July 27, 2013
  18. geometry

    What is the meaning of P(6,6)? Is it the value of P(x,y) where x = y = 6? Is that 2/(3x) or (2/3)*x on the right?

    posted on July 27, 2013
  19. MAT LAB

    unanswered You have used 0 of 4 submissions

    posted on July 27, 2013
  20. Physics

    f = (1/2pi)*sqrt(k/M) Hz M = 1481 kg k = 81*9.8/0.015 = 52900 N/m f = 5.0 Hz.

    posted on July 27, 2013
  21. General Physics

    The kinetic energy does not change. What does that tell you?

    posted on July 26, 2013
  22. physics

    delta S = entropy change = 1.6*10^5*[1/293 - 1/T2] = 470 Solve for T2

    posted on July 26, 2013
  23. science

    frequency = 600 Hertz (beats per second) Wavelength = (speed of sound)/(frequency) = (340m/s)/600 (s^-1) = 0.57 m

    posted on July 26, 2013
  24. physics

    What are the dimensions of the 2.05? Meters displacement?

    posted on July 25, 2013
  25. math

    You want to know Young's and the shear modulus, E and G, not Young's and shear modules. The equations you need can be found at http://silver.neep.wisc.edu/~lakes/PoissonIntro.html Your last sentence is incomplete.

    posted on July 25, 2013
  26. earth

    ____ cubic meters, since r is in meters.

    posted on July 24, 2013
  27. physics

    Let ds be the density of steel in kg/liter. Let df be the average density of gasoline. You will need to look it up. Avg density = [2.6 + 15/df]/[2.6/ds + 15]

    posted on July 19, 2013
  28. Physics

    The ratio of the resistances will be the same as the ratio of the resistivities, if lengths and diameters are the same. R(Cu)/R(Al) = 1.72 x 10-8/2.82 x 10-8 = 0.61 R(Al) = 0.509 Ù

    posted on June 6, 2013
  29. heeeeeeeeeeeelp physics vrey tough

    Never mind the General Relativity approach I suggested. Time goes slower at the lower orbit because of Special relativity . Use the two different satellite speeds to deduse the time shift for one orbit. You want the extra credit.. so you do the numbers

    posted on June 5, 2013
  30. heeeeeeeeeeeelp physics vrey tough

    I assume you are being asked about the change in the rate of a clock in a gravitational field (of the sun, in thic case). There is a General Relativity formula for it. (Due to Schwarzschild, I believe) delta T = T*(delta V)/c*2 V is the gravitational

    posted on June 5, 2013
  31. physics

    What does the symbol h represent? The arrow from reactants to products? Here is one answer. 3 H2(g) + N2(g)-> 2 NH3(g) The others are not hard. You need to try them yourself.

    posted on June 3, 2013
  32. Physics

    Plane mass increases by a factor of 2^3 = 8. Plane lift increases by a factor 2^2 = 4 Plane drag increases by an unknown factor between 1 and 2. Engine power will have to increase to compenstate for increased prssure drag and boundary layer friction. The

    posted on June 2, 2013
  33. math

    3% gets compounded 20 times. 5000*(1.03)^20 = $9030.56

    posted on June 1, 2013
  34. SCI/220 HUMAN NUTRITION

    What questions?

    posted on June 1, 2013
  35. physics

    What kind of length unit is "hm"?

    posted on June 1, 2013
  36. physics

    Don't you mean 90 m/hr? I have never heard of a length unit abbreviated "hm"

    posted on June 1, 2013
  37. physics

    How fast is it accelerating? You don't say. To get the power required, you need the kinetic energy at a later time, or the rate of acceleration.

    posted on June 1, 2013
  38. physics

    Your numbers require units. That is one of the first lessons you ahould have learned about physics.

    posted on June 1, 2013
  39. Math Linear function help?

    The slope of the line is m = (y2-y1)/(x2-x1) =(3-6)/(4-0) = -3/4 When x = 0, y = 6, so the y-intercept is 6. y = (-3/4)x + 6 is the equation you want.

    posted on May 31, 2013
  40. Physics

    The E-field in any direction is the rate of change of potential with distance along that direction. The a question contains the words"the following", you really must state what the choices are. And please stop changing names.

    posted on May 31, 2013
  41. Physics

    what are the choices?

    posted on May 31, 2013
  42. physics

    Recheck you numbers. Telescopes have long focal lengths and their eyepieces (if used) have short focal lengths. The telescope length, if you are using a refractor, is the sum of the objective and eyepiece focal lengths. Assuming you got the numbers mixed

    posted on May 30, 2013
  43. physics

    (average velocity)*(time) = 23.9 m/s*12 s = 286.8 m

    posted on May 30, 2013
  44. Physics

    Write an equation for the E-field along the line joining the two charges. Let the position of the charge be x. Set the E-field equal to zero and solve for x. You can assume that x has to be > 50 cm, so that the fields due to the two charges oppose each

    posted on May 30, 2013
  45. Physics

    At 60,000 Pa gauge pressure, the absolute pressure inside the ball is 101,325 + 60,000 = 161,325 Pa Dropping the absolute temperature from 293 to 283 K decreases the absolute pressure in the ball by a factor 283/293, resulting in 15,582 Pa. Subtract

    posted on May 30, 2013
  46. Physics

    What you have written in not a balanced chemical reaction. Where is the arrow (->) ? An arrow must separate the two sides of the reaction. What is h2? Cr2O3 is not a gas

    posted on May 30, 2013
  47. science

    "Plaastids" is misspelled. You will have to write your own poem. This may help: http://www.readwritethink.org/files/resources/interactives/acrostic/

    posted on May 29, 2013
  48. Sam

    No work is done, because the dock does not move. However, some of the kinetic energy of the wave will be converted to heat and small-scale vorticity and turbulence in the water. A large fraction of the ocean wave energy will also be reflected by the dock.

    posted on May 29, 2013
  49. sam

    Someone left out the word WORK in your question. The question should read: "How much Work do you do if you push a garbage can with a force of 30N while sliding it 4 meters" The answer is Work = Force x Distance, which is 120 Joules in this case.

    posted on May 29, 2013
  50. language (sentence fluency)

    D. is most fluent

    posted on May 29, 2013
  51. Geometry

    You should rethink 4. 2. is 'sometimes'. Consider the isosceles case. 3. is true because of the law of sines

    posted on May 29, 2013
  52. maths

    For d/dx (3x+2)^n, let u(x) = 3x + 2 f(u(x)^n)= u^n df/dx = (df/du)*(du/dx) = 3*n*u^(n-1) = 3n*(3x+2)^(n-1) For d/dx(2x+3)^m, Let v(x) = 2x +3 g(v(x)^m) = v^m dg/dx = (dg/dv)*(dv/dx) = 2 mv^(m-1) Add the two terms d/dx [(3x+2)^n +(2x+3)^m] =

    posted on May 29, 2013
  53. physics

    Draw a free body diagram and set the total moment about the fulcrum/pivot equal to zero. Let x be the distance of the elder brother from the pivot. 80*x = 50*2 + 30*7 = 310 N*m x = 3.87 m (on the opposite side of the pivot from the 30 N brother) This

    posted on May 29, 2013
  54. physics

    Speed is constant and direction is not changing. Therefore acceleration is zero.

    posted on May 29, 2013
  55. Physics

    The sum of the individual resistances: 15.0 ohms. You do not need the battery voltage for that question.

    posted on May 29, 2013
  56. MATH

    One row of five posts across from the stream. Two rows of four perpendicular to the stream. Total = 13

    posted on May 29, 2013
  57. science

    250 ml of a 1.0 M glucose solution contains 0.25 moles of glucose. Each mole of glucose has a mass of 180 g. 0.25 x 180 = ___ g

    posted on May 29, 2013
  58. algebra

    (a) [f(3) - f(1)]/(3-1) = (28-4)/2 = 12 (b) [f(5) -f(3)]/(5-3) = (76-28)/2 = 24 (c) [f(4) - f(1)]/(4-1) = (your turn)

    posted on May 28, 2013
  59. math

    ab is not a fraction. It is a product. 56% = 14/25 14 and 25 are coprime numbers a and b. Their sum is a + b.

    posted on May 28, 2013
  60. Physics

    (a) +162 F = 90 C (b) 90 K Each 1.8 degree rise in deg F is a 1.0 degree rise in the C or Kelvin Temperature.

    posted on May 28, 2013
  61. Physics

    (a) 3 m/s is not an acceleration rate. You probably mean 3 m/s^2. (b) Weight = M*g = 490 N (c) 3 m/s is not a deceleration rate.

    posted on May 28, 2013
  62. middle madness

    X - 15 - 8 -[(X-15-8)/2) = 46 (X-23)/2) = 46 X -23 = 92 X = 115

    posted on May 28, 2013
  63. science

    Please be more careful with your spelling. A chemical reaction in which two or more substances undergo a chemical union to form a more complex substance is: a Direct Combination or Synthesis Reaction

    posted on May 28, 2013
  64. Physics

    It is four times the potential due to a charge at a single corner. Your equation 1/4¦Ð = 8.99 ¡Á 10^9 N ¡¤ m2/C2 is obviously incorrect. The distance from the center of the square to a corner is R = 1.414 m The potential due to a single corner charge

    posted on May 28, 2013
  65. Physics

    They have already told you that the velocity of the truck (less sand) remains the same. The momentum of the truck (less sand) therefore also stays the same.

    posted on May 28, 2013
  66. Physics

    The friction force in the reverse direction is 200*0.4 = 80 N. The net forward force acting on the box is therefore Fnet = 100 - 80 = 20 N Acceleration = Fnet/Mass = Fnet*g/(Weight) = 20*9.8/200 = 0.98 m/s^2

    posted on May 27, 2013
  67. math

    Your numbers require dimensions. Inches? Centimeters? Meters?

    posted on May 27, 2013
  68. physics

    The volume of the steel in the coil is V = Length*Width*Thickness = (mass)/(density) = 156 kg/7.9*10^3 kg/m^3 = 1.98*10^-2 m^3 Length = 1.98*10^-2/(0.5)(8*10^-4) = 49.4 meters I have used an "average" density for steel. If you know the alloy type, you can

    posted on May 27, 2013
  69. power dissipation

    I = 40V/40,000 ohms = 10^-3 A goes through each resistor, since they are in series. The power dissipated in R1 is I^2*R1 = 10^-6*10,000 = 10^-2 watts

    posted on May 25, 2013
  70. PHYSICS

    1. Use conservation of momentum. Let the initial direction of X be considered positive. 20 - 12 = -2 + (momentum of Y) Momentum of Y = 10 N*s 2. Momentum of Force*t = 20i + 70j (N*s) is added to the body Initial momentum = 5i -10j Final momentum = 25i + 60

    posted on May 25, 2013
  71. algebra

    If "diffance" means difference, the answer is 20. You don't need to use algebra.

    posted on May 25, 2013
  72. physics

    Convert all speeds to the same units and than compare them. For the bicycle, 18 km/h = 18000 m/3600 s = 5.0 m/s For the car 2 km /min = 2000 m/60 s = 33.3 m/s The athlete runs at 7 m/s. The bike is slowest and the car is fastest in this case.

    posted on May 25, 2013
  73. science

    Don't you mean Fe + 2HCl -> FeCl2 + H2 ? 55g Fe is 0.984 moles 36.5 g HCl is 1.000 moles HCl is slightly in excess of stoichiomentric. 0.984 moles of HCl are evolved. That is 22 liters at STP

    posted on May 24, 2013
  74. physics

    The magnetic field B provides the centripetal force to keep it in a circular path. e V B = m V^2/R R = mV/(eB) m and e are the electron mass and charge. You don't need the Biot Savart Law for this question. There are plenty of good explanations of it

    posted on May 24, 2013
  75. Physics

    Are you talking about sound waves? You need the speed of wave propagation to answer the question. For sound in air, it is about 340 m/s. Wavelength = (Wave speed)/(Frequency) You do not need to make approximations for pi to do the calculation.

    posted on May 23, 2013
  76. chem ! help its killing me to :/

    This is not a service where long homework assignments are done for you. You have to make an effort. Learn and apply the ideal gas law.

    posted on May 23, 2013
  77. Physics !!!!! HELP PLEASE

    K.E. is (1/2) M V^2 To get it in Joules, M must be in kg. bullet KE = 960 Joules If motorcycle KE = 960 J,and its mass is 173 kg, (1/2)*173*Vm^2 = 960 then the motorcycle velocity is Vm = 3.33 m/s Convert that to km/h

    posted on May 23, 2013
  78. physics

    Use the principle of superposition. The E field at the center will be the sum of two cases: (a) +3 microC at the open corner, and all three other corners (b) -6 microC at the open corner location only Case (a) results in a net E field at the center of

    posted on May 23, 2013