Saturday
October 22, 2016

# Posts by David

Total # Posts: 2,085

physics
A rod with length L and mass m stand on a frictionless table. a ball with mass m and speed u cimped perpendicular to the rod a distance x from the bottom of the rod and sticks to it. what is the angular velocity of the rod+ball after the collison? I need help on how to solve ...
January 27, 2015

math
if your body releases about a liter of saliva a day how many years to release a kiloliter
January 25, 2015

math
what are all the rectangular pens you can build with 16 yds of fencing
January 25, 2015

Physics
A car slows down from a speed of 24.0m/s to rest in 9.0s, How far did it travel in that time?
January 24, 2015

Physics
car leaves skid mark 72m in length with a deceleration speed of 7.20m/s^2. what was the initial speed prior to braking?
January 24, 2015

Physics
A car leaves skid marks 72m in length. The deceleration is 7.2m/s^2. What is the speed of the car before braking?
January 23, 2015

Chemistry
How much energy (in kilojoules) is released when 15.2g of steam at 114.5∘C is condensed to give liquid water at 63.5∘C? The heat of vaporization of liquid water is 40.67 kJ/mol, and the molar heat capacity is 75.3 J/(K⋅mol) for the liquid and 33.6 J/(K⋅...
January 21, 2015

accounting
January 13, 2015

english
Write a narrative essay that ends with 'once beaten, twice shy'
January 13, 2015

physics
A heavy table of mass M is vibrationally isolated by being hung from the ceiling by springs, so that its frequency of vertical oscillation is \omega_0 (take \omega_0 to be 2\pi/sec, a typical value). Assume now that the ceiling vibrates vertically with amplitude A at frequency...
January 8, 2015

Math
1) Prove that for every x>=0 and 0<a<1 x^a-ax<=1-a 2)prove that for 0<=x<=1: x^m*(1-x)^n<= (m^m*n^n)/((m+n)^(m+n)) can someone please guide/help me in about how to solve and or approch these questions? (I know I have already posted it before but i think it...
January 7, 2015

Math
1) Proove that for every x>=0 and 0<a<1 x^a-ax<=1-a 2)prove that for 0<=x<=1: x^m*(1-x)^n<= (m^m*n^n)/((m+n)^(m+n)) can someone please guide/help me in about how to solve and or approch these questions?
January 7, 2015

Science
Yes, the answers are: 1.C 2.B 3.B 4.D
January 6, 2015

programming
It is a computer course for physicists. Therfore i do not study programming as my main course. also i have missed a few lessons, therfore i do not even know where to begin.
December 26, 2014

programming
– Define a structure called Object which includes three doubles specifying the object’s mass, volume and density. – Create an array of 10 Objects. – Define the function void scanobjectsdata(struct Object objects[], int size) that scans from the input and ...
December 26, 2014

AP Calc
Find the value of c which satisfies Rolle’s Theorem for the function f(x)=sin(x²) on (0,√π).
December 20, 2014

Physics
A 283 g air track glider moving at 0.69 m/s on a 2.4 m long air track collides elastically with a 467 g glider at rest in the middle of the horizontal track. The end of the track over which the struck glider moves is not frictionless, and the glider moves with a coefficient of...
December 14, 2014

Physics
A 283 g air track glider moving at 0.69 m/s on a 2.4 m long air track collides elastically with a 467 g glider at rest in the middle of the horizontal track. The end of the track over which the struck glider moves is not frictionless, and the glider moves with a coefficient of...
December 12, 2014

Calculus
Thanks!
December 10, 2014

Calculus
This is a calculus homework question but in reality the problem here is understanding the algebra. Find the Critical Numbers of f(x) = x^(3/5)(4-x) The product rule gives -x^(3/5) + (12-3x)/(5x^(2/5) My booklet explains that simplifying this gives you 12-8x / (5x^(2/5). How ...
December 10, 2014

Calculus
in the equation a/(1-r)
December 8, 2014

Calculus
so a is the first term in the series and r is the term that is being reused over and over again ?
December 8, 2014

Calculus
So this one is confusing me: limit of n as it approaches infinity of (n{SIGMA}i=1) (1/(2^i) *the n is on top of the sigma notation and i=1 is at the bottom. I understand that 'i' would equal (n(n+1))/2 however the algebra from there confuses me.
December 8, 2014

Calculus
I am trying to solve the following L'hopital's limits question below: lim x -> 0 from the positive direction of ( 5^(sin(x)) - 1 )/ (x)
December 8, 2014

Calculus
L'hopital's question below: lim x -> 0 from the positive direction of ( 5^(sin(x)) - 1 )/ (x)
December 7, 2014

AP Chemistry
What percent (by mass) of granulated sugar is fructose, and what percent of it is sucrose? Background: We are doing a colligative properties lab in my class where we are to add 20 grams, 40 grams, 60 grams, and 80 grams of sugar to 100 grams of water, and use the change in the...
December 6, 2014

AP Chemistry
What is the Van't Hoff Factor of MgSO4*7H2O? We're doing a colligative properties lab at my school where we dissolve various amounts of MgSO4 in 100 grams of water. What value/range of values should I expect the Van't Hoff Factor to be?
December 6, 2014

Physics
You have a brass ring of inside diameter 10.00 cm that is at 20.0oC. You want to slip this ring over an aluminum rod that is at 20.0oC and has a diameter of 10.01 cm. a. To what temperature do you have to heat the ring to slip it over the rod? b. Once you have the ring over ...
December 4, 2014

Biology
Which alga is most closely related to plants? A) Chara B) Kelp C) Ulva D) Diatom E) Euglena I think it's chara, because it is green algae, but I'm not sure. Can you explain to me why it is or not?
November 20, 2014

Math
23 multiplied by 12= 276 276-15= 261 The answer is 261
November 20, 2014

physics
A person is stranded and sitting 45m above the ground on the ledge of the cliff. of a safety rope is launched upward at an angle of 50 degrees above the horizontal at a distance of 60m away, what is the initial velocity of the rope so that it reaches the stranded person?
November 19, 2014

physica
help A thermally insulated vessel containing 100 grams of ice at 0 degrees Celsius . Water at 55 degrees celsius is poured and after some time , the system reaches the equilibrium at a temperature of 10 degrees Celsius. That amount of water in grams was placed . ( heat fusion...
November 17, 2014

Math
In a coordinate plane, Brittany labeled the coordinates for point m as (-31/2,2). Sade tells Brittany to reflect point m over the x axis to point r. What are the coordinate of point r?
November 16, 2014

physical
help the positions of two particles A and B are P1 (3,4) in meters and P2 ( -3, -4 ) meters respectively. Meters the position A with respect to B is:
November 14, 2014

physics
A space station shaped like a giant wheel has a radius of 1.00 x 10^2 m and a moment of inertia of 5.00 x 10^8 kgm^2. A crew of 150 lives on the rim, and the station is rotating so that the crew experiences an apparent acceleration of 1.0g. When 120 people move to the center ...
November 11, 2014

physics
a 2100 kg car starts from rest and accelerates at a rate of 2.6 m/s for 4 sec. assume that the force acting to accelerate the car is acting in the same direction as its motion. how much work has the car done? m=2100 kg w=fd v1=0 f=ma t=4 sec d=t+1/2at(squared) a=2.6 m/s2
November 11, 2014

I believe it's A correct me if I'm wrong though.*
November 10, 2014

I believe it's B correct me if I'm wrong though.
November 10, 2014

Physics
A moving 4.5 kg block collides with a horizontal spring whose spring constant is 226 N/m (see figure). The block compresses the spring a maximum distance of 8.0 cm from its rest position. The coefficient of kinetic friction between the block and the horizontal surface is 0.47...
November 9, 2014

Engineering science
a roller of diameter 1.5 m has a mass of 450 kg; it is pulled by a handle attached to its centre. Find the minimum force to pull up a step which is 250 mm high if the roller handle makes an angle of 30o with the horizontal
November 9, 2014

math
Rounded to what? Currently it is rounded to the nearest thousandth. If you were to round it to the nearest hundredth it would be 0.08 and to the nearest tenth 0.1.
November 6, 2014

Intermediate Algebra
(-9)1/2 = -4.5 which is a real number. Unless you're talking about square roots?
November 6, 2014

chemistry
The trend for electron affinity on the periodic table is that it increases from the bottom left of the table to the top right. He>I>Te>Bi>Na Should be the order.
November 6, 2014

Science HELP
Due to the conservation of mass, the mass of the reactants is equal to the mass of the products. Mass(A) + Mass(B) = Mass Solid Product 10g + 17g = 27g Mass(beaker) = Mass(Beaker + product) - Mass (product) So Mass(Beaker) = 32g - 27g = 5g So your answer is "A. 5g."
November 6, 2014

Math
I'm not entirely sure what you are asking, but I'll give it a shot. (5x4) + (1x4) is NOT the same as 6x8. Lets look at it in detail: 6x8 = 48 5x4 = 20 and 1 x 4 = 4 20 + 4 = 24 which is not 48. The most you could do is some factoring, but you have to make sure your ...
November 6, 2014

Science HELP
Zn(s) + 2HCl(aq) ---> ZnCl2(aq) + H2(g) It is D, but don't forget to include the extra hydrogen atoms, or else the equation violates the law of conservation of mass. In this case, hydrogen gas (H2) is formed.
November 6, 2014

Science
Due to the conservation of mass, the mass of the reactants is equal to the mass of the products. Mass(A) + Mass(B) = Mass Solid Product 10g + 17g = 27g Mass(beaker) = Mass(Beaker + product) - Mass (product) So Mass(Beaker) = 32g - 27g = 5g So your answer is "A. 5g."
November 6, 2014

math
7 books to wrap, each 5/6 of a foot long. how long a roll needed 7x12 =84 5/6x7=35/42?
November 6, 2014

Algebra HELP!
Part A: Lets say the number any student chooses is 'x'. We need to perform operations to get to 'x-1'. There are many possibilities for this. For example, consider the following scenario where the student is 's' and the teacher is 't'. I'll ...
November 6, 2014

physics
A particle undergoes three successive displacement in a plane as follows 4m southwest, 5m east, 6m in a direction 60 degree north of east (a) draw an apropraite vector diagram to represcent the displacement (b) detarmine the displacement that would be required to bring the ...
November 4, 2014

physics
A hollow 0.358 kg sphere rolls without slipping down an inclined plane that makes an angle of 41.0o with the horizontal direction. The sphere is released from rest a distance 0.734 m from the lower end of the plane. a. How fast is the hollow sphere moving as it reaches the end...
November 3, 2014

physics
A hollow 0.358 kg sphere rolls without slipping down an inclined plane that makes an angle of 41.0o with the horizontal direction. The sphere is released from rest a distance 0.734 m from the lower end of the plane. a. How fast is the hollow sphere moving as it reaches the end...
November 3, 2014

Physics
Creating Z_0 boson via symmetric beams a. Z0 boson has a rest mass energy of 91.187 GeV. It is produced in collisions of positrons and electrons. e^- + e^+ to Z_0 How much kinetic energy must the positrons and electrons in symmetric colliding beams have to produce the Z0 boson...
October 30, 2014

Physics
Creating Z_0 boson via symmetric beams a. Z0 boson has a rest mass energy of 91.187 GeV. It is produced in collisions of positrons and electrons. e^- + e^+ to Z_0 How much kinetic energy must the positrons and electrons in symmetric colliding beams have to produce the Z0 boson...
October 30, 2014

Physics
A 0.250-kg ice puck, moving east with a speed of 5.26m/s , has a head-on collision with a 0.990-kg puck initially at rest. Assume that the collision is perfectly elastic.What is the speed of the 0.250-kg puck after the collision?
October 29, 2014

Chemistry
The reaction of iron and water vapor results in an equilibrium reaction, 3 Fe(s) + 4 H2O(g) ¡ê Fe3O4(s) + 4 H2(g) and an equilibrium constant of 4.6 at 850¡ÆC. What is the concentration of Hydrogen present at equilibrium if the reaction is initiated ...
October 28, 2014

physics
A figure skater is spinning with an angular velocity of +10 rad/s. She then comes to a stop over a brief period of time. During this time, her angular displacement is +5.8 rad. Determine (a) her average angular acceleration and (b) the time during which she comes to rest.
October 27, 2014

Biology
Compare ad contrast indirect versus direct values of biodiversity and provide two examples?
October 24, 2014

physics
A small pumpkin of mass 2.22 kg is dropped from rest from a height of 2.87 m. The pumpkin rebounds from the ground to a height of 1.12 m. a. With what speed does the pumpkin hit the ground? b. With what speed does the pumpkin leave the ground? c. What impulse was given to the ...
October 24, 2014

physics
vf1= ((m1-m2)/(m1+m2))(v1) vf2= ((2m1)/(m1+m2))(v1)
October 23, 2014

The sweet candy shop buys 600 pounds of chocolate covered strawberries at $5.59 per pound. If a 10% spoilage rate is anticipated, at what price per pound should the strawberries be sold in order achieve a 60% markup based on cost? October 20, 2014 Estimating decimal quotient 180.8/6=180/6=30 18.2/11=20/10=2 55/10.7=50/10=5 0.6/5=1.0/5=0.2 145/0.3=145/3=15 60/5.9=60/6=10 1.8/20=2.0/20=0.1 October 19, 2014 Estimating decimal quotient Use compatible to find the following quotient 180.8 divided by 6 182divided by 11 55divided by 10.7 117.8divided by 0.12 0.6 divided by 5 145 divided by 0.3 60 divided by 5.9 1.8 divided by 20 October 19, 2014 Business Math Jeanna wants to buy a new boat for her family. She has two payment options. The first option is to pay a cash payment of$7,200. The second option is to finance the boat with a three year installment loan. The loan requires a 10% down payment and 36 equal monthly payments of $... October 19, 2014 Biology Compare and contrast indirect versus direct values of biodiversity, and provide examples. October 17, 2014 Math Every item in the Just a Dollar store is priced at$1.00. When Mary Jo opens the store, there is $122.00 in the cash register. When she counts the money in the cash register at the end of the day, the total is$1,065.95. If the sales tax rate is 8.5%, how many items were sold ...
October 13, 2014

Algebra
please help me im confused. Every item in the Just a Dollar store is priced at $1.00. When Mary Jo opens the store, there is$122.00 in the cash register. When she counts the money in the cash register at the end of the day, the total is \$1,065.95. If the sales tax rate is 8.5...
October 13, 2014

physics
The weight of an astronaut plus his space suit on the Moon is only 270 N. A. How much do they weigh on Earth, in Newtons, assuming the acceleration due to gravity on the moon is 1.67m/s^2= 1584is this right? B. What is the mass of the astronaut and his space suit on the moon ...
October 9, 2014

physics,electrostatics
A 40uf parallel plate capacitor is charged to 12v. The capacitor is removed from the battery and the separation distance increased from 2mm to 3mm. What is the total charge on the capacitor? How much energy was stored in the capacitor when the distance was 2mm? By how much is ...
October 9, 2014

science
planetary accretion
October 7, 2014

math
Hold on Sir... you have lots of questions going on here please wait a few min before a tutor gets to you Thanks :D
October 7, 2014

AP Calc
Find the equation of ALL horizontal tangents to the curve y^2=x^2+4/x, if any exists. My work: Derivative- First I multiply across and got x^2+4=xy^2 2x+0=(x)(2y(dy/dx)+(y^2) 2x-y^2=2xy(dy/dx) dy/dx=2x-y^2/2xy=x-y^2/xy I don't know what to do next... Can you help me? ...
October 6, 2014

AP Calc
Find the point on the curve x=4y-y^2 where the tangent to the curve is a vertical line. My work: Finding the derivative. 1=4(dy/dx)-2y(dy/dx) 1=dy/dx(4-2y) dy/dx=1/4-2y Therefore, y cannot equal +2 or -2 Right?
October 6, 2014

Math
The answer is -13.482 if you want it in Sig. Figs then the anser will be -13.4 Hope this helped :D
October 6, 2014

math
f(x)=(x-3)(x+2) If thats what you're looking fore :) To solve for x if you're going further Use T-Chart... answer then will be x=3 and x=-2
October 6, 2014

Math
1/5^9= 5.12 x 10^-7 Work backwards: 1/5 is the conjugate of 5 therefore, if 1/5 is raised to the 9th power the opposite of that is -9. 5^-9= 5.12 x 10^-7 your answer: B
October 6, 2014

Math
Find the point on the curve x=4y-y^2 where the tangent to the curve is a vertical line. My work: Finding the derivative. 1=4(dy/dx)-2y(dy/dx) 1=dy/dx(4-2y) dy/dx=1/4-2y Therefore, y cannot equal +2 or -2 Right?
October 6, 2014

Physical Education
Correct Carbohydrates are the main energy source to the human body :)
October 6, 2014

Physical Education
Carbohydrates are the main energy source for the brain. Without carbohydrates, the body could not function properly. Protein is the major structural component of cells and is responsible for the building and repair of body tissues. Protein is broken down into amino acids, ...
October 6, 2014

Math
Thanks I understand it now :D
October 6, 2014

Math
Find the coordinatesof the point on the curve xy=10 in the first quadrant such that the normal line passes through the orgin. My work: Okay i believe this is an inverse variation. Therefore, y=10/x? Origin is @ (0,0) and i'm stuck to move on...
October 6, 2014

Math- AP Calc
If 3x+xy+4y=8, what is the value of d^2y/dx^2 at the point (1,1)? My work: 3+(x)(dy/dx)+(y)+4(dy/dx)=0 dy/dx(x+4)=-3-y dy/dx=-3-y/x+4 2nd Dervative: (x+4)(0-dy/dx)-(-3-y)/(x+4)^2 (x+4)(-(-y-3/x+4))-(-3-y)/(x+4)^2 (x+4)(y+3)/(-x+4)+(y+3)/(x+4)^2 *Mult. everything by (-x+4) ...
October 6, 2014

Math
If 3x+xy+4y=8, what is the value of d^2y/dx^2 at the point (1,1)? My work: 3+(x)(dy/dx)+(y)+4(dy/dx)=0 dy/dx(x+4)=-3-y dy/dx=-3-y/x+4 2nd Dervative: (x+4)(0-dy/dx)-(-3-y)/(x+4)^2 (x+4)(-(-y-3/x+4))-(-3-y)/(x+4)^2 (x+4)(y+3)/(-x+4)+(y+3)/(x+4)^2 *Mult. everything by (-x+4) ...
October 6, 2014

math
How do you do this problem f(x)=3x6+2x3-176;c=-2
October 6, 2014

geometry
Point C is in the interior of angle ABD. The measure of angle ABD is 40 degrees. The measure of angle DBC is 3x-5. If angle ABC is 22 degrees, what is "x"?
September 28, 2014

algebra
oh 65 and 66.
September 23, 2014

algebra
65 and 67?
September 23, 2014

algebra
its 65.5
September 23, 2014

algebra
the numbers on two consecutively numbered gym lockers have the sum of 131. what are the locker numbers?
September 23, 2014

math
-5 an 7/12 divided by 12 equals
September 23, 2014

Chemistry
Is it about 2 Zums?
September 22, 2014

Chemistry
8.5 Ed's = 10 Ebb's, 12 Ersk's = 100 Ed's and 5 Ebb's = 1 Zum. How many Zum's in approx. 1 Ersk? Starts out: 1 Ersk*__________ Ersk
September 22, 2014

Physics
The nozzle of a fountain jet sits in the center of a circular pool of radius 3.50 m. If the nozzle shoots water at an angle of 65 degrees. A) What is the maximum speed of the water at the nozzle that will allow it to land within the pool?
September 21, 2014

math
1) 4.1875 = 4 3 over 16 2) 4.5 = 4 1 over 2 3) 4.625 = 37 over 8 4) 4.75 = 19 over 4
September 21, 2014

Physics
is your d = square root of (60^2 + h basket^2) and for which question a,b or c
September 21, 2014

Physics
A Balloon carrying a basket is descending at a constant velocity of 20.0 m/s. A person in the basket throws a stone with an initial velocity of 15.0 m/s horizontally perpendicular to the path of descending balloon and 4.00 (s) later this person sees the stone strike the ground...
September 21, 2014

Pshyics
A meter stick has a mass of 0.12 kg and balances at its center. When a small chain is suspended from one end, the balance point moves 19.0 cm toward the end with the chain. Determine the mass of the chain.
September 21, 2014

Pre-Cal
Let x and y be real numbers such that x^2 + y^2 = 1. Find the maximum value of 2x - 5y.
September 20, 2014

Physics
A particle is moving at 0.75c relative to a lab on Earth. By what percentage is the Newtonian expression for its momentum in error, i.e., how wrong is the classical formula? (The percentage error is the difference between the erroneous and correct values, divided by the ...
September 20, 2014

Algebra 2
The line 4x + ky = -1 has a slope of 2/3. Find k. a. 3/2 b. 6 c. -3 d. -6
September 17, 2014