# Posts by David

Total # Posts: 2,249

**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*

**business math**

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 that's 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*

**Math**

You deposit $100 at the end of each quarter in a sinking fund earning 4% compounded quarterly. How many quarterly deposits must you make in order to reach your goal of saving $10,000? Round your answer off to the nearest whole number.

*September 15, 2014*

**physics**

your mom

*September 4, 2014*

**math**

I DO NOT FREAKING KNOW

*August 26, 2014*

**5th grade math**

289 x 7=2023

*August 25, 2014*

**Chemistry**

8-hydroxyquinoline (Q) can complex and precipitate many metals. A mixture of the aluminium and magnesium complexes weighed 1.0843g (MW=459.43; 312.61). When ignited, the mixture decomposed and left a residue of Al203 (MW 101.96) and MgO (MW 40.304) weighing 0.1344g. What is ...

*August 24, 2014*

**computers**

create a program that will input two quizzes and will compute for sum,difference,product,quotient and average using printf and scanf. create your own design.

*August 21, 2014*

**Math**

1165

*August 20, 2014*

**MATH**

The first month's dues will be used to rent a film about computer-related careers, to purchase a reference book, and to buy refreshments for the next meeting. If 1/2 of the money is spent on her film, 1/4 of the remainder is used for refreshments, and $7.50 is spent on the...

*August 12, 2014*

**math**

The answer is c

*August 7, 2014*

**computers**

when you connect to a remote VPN server with your laptop running windows 8 what key item is your computer allocated

*August 7, 2014*

**Chemistry**

Why the ph will be determinated as if you have 0,05M H3PO4???

*August 7, 2014*

**math hw**

42. Twenty minutes after a plane leaves the airport, it is reported to be 160 miles away. What average speed of the plane in the miles per hour?

*August 5, 2014*

**math hw**

An automobile party leaves at 7:55 A.M., and arrives at its destination 15 miles away at 8:15 A.M. What was the average rate on this trip (in M.P.H.)?

*August 5, 2014*

**math hw**

40. How far (in miles) does a car travel when its average rate is 35 miles per hour and it travels for 3 hours and 24 minutes?

*August 5, 2014*

**math test review**

18. In triangle ABC, m<C=2m<b,m<A=6m<B. what is the measure of <c? A.5 degrees B.15 degrees C.20 degrees D.30 degrees E.40 degrees

*August 4, 2014*

**math**

That was by mistake, I didn't know and typed in again.

*August 4, 2014*

**math**

1. If b is positive integer less than 200, then how many integer pairs (a,b) satisfy the equation a/b= 2/9?

*August 4, 2014*

**math**

1. If b is a positive integer than 200, then how many integer pairs (a,b) satisfy the equation a/b= 2/9

*August 4, 2014*

**math test review**

16. If the base of a right triangle is 8 (square root)2 and the hypotenuse is 18, what is the area of the triangle? A.14 B.14 square root 2 C.56 square root 2 D.64 E.64 square 2

*August 4, 2014*

**math hw**

In set of 30 different positive integers, every number is even and/or a multiple of 3. If 22 of these numbers are even and 15 are multiple of 3, then how many of these numbers are multiple of 6?

*August 4, 2014*

**math hw**

2. If a^2-b^2=20 and a+b=2, what is the value of a-b? I added the a^2-b^2+20 and a+b+20, but i couldn't get the answer to equal a-b.

*August 4, 2014*

**math hw**

10.Thirty students in a chemistry class took a test on which the overall average score was 78. If the average score for 15 of those students was 85, what was the average score for the remaining members of the class? I know that "average" means dividing, but i'm ...

*August 4, 2014*

**math**

9. In Mr.chin's math class there were g girls and b boys. The number pf girls was 5 less than twice the number of boys. What is the value of g in terms of b? this is what I have so far: 2n-5

*August 4, 2014*

**Chemistry**

2Na + 2H2O------> 2NaOH + H2 H=-386kJ If 5g of sodium is added to 200g of water in an open container: (A) How much heat is absorbed/released int he reaction? (B)What volume in formed at 22C and 102kPa? (C) If boiling point elevation constant is 0.52K molal what is the ...

*August 3, 2014*

**maths**

The Park's are buying new carpet for their house.They need about 1,175 square feet of carpet.The carpet they buy is sold by the square yard. Estimate the number of square yards of carpet the Parks need for their house. Show your work.

*August 2, 2014*

**Astronaut launches bowling ball**

A 100 kg astronaut carries a launcher loaded with a 10 kg bowling ball; the launcher and the astronaut’s spacesuit have negligible mass. The astronaut discovers that firing the launcher results in the ball moving away from her at a relative speed of 50 m/s. The astronaut ...

*July 28, 2014*

**English**

She waited patiently for her turn on line at the New Age bookstore. adjective adverb noun verb

*July 6, 2014*

**Physics**

. A stone is dropped from the top of a building that is 500m high. Disregarding air resistance how long does it take the stone to reach the ground?

*June 25, 2014*

**math**

20

*June 8, 2014*

**math**

Charlie must choose a number between and that is a multiple of , , and . Write all the numbers that he could choose. If there is more than one number, separate them with commas

*May 28, 2014*

**Physics**

A 69.5kg football player is gliding across very smooth ice at 2.15m/s . He throws a 0.470kg football straight forward. A) What is the player's speed afterward if the ball is thrown at 16.0m/s relative to the ground? B) What is the player's speed afterward if the ball ...

*May 27, 2014*

**Math please check my answer?**

1)6x+11y=30 A) x-intercept= (-24,0);y intercept =(0,19) B)x-intercept=(0,1/5);y intercept=(11/30,0)<<<< C)x-intercept= (5,0);y intercept=(0,30/11) D)x-intercept= (24,0);y intercept=(0,19)

*May 22, 2014*

**Math please check my answers?**

1) The linear function f(x) contains the points (-10, -29) and (-2, 83). If g(x) = 25x - 50, which statement is true? A. The functions f(x) and g(x) both have positive slopes. <<< B. The functions f(x) and g(x) both have negative slopes. C. The function f(x) has a ...

*May 22, 2014*

**Algebra please check my answers**

Are 1 and 2 correct?

*May 21, 2014*

**Algebra please check my answers**

Thanks! Are the others correct?

*May 21, 2014*

**Algebra please check my answers**

1) The linear function f(x) contains the points (-10, -29) and (-2, 83). If g(x) = 25x - 50, which statement is true? A. The functions f(x) and g(x) both have positive slopes. <<< B. The functions f(x) and g(x) both have negative slopes. C. The function f(x) has a ...

*May 21, 2014*

**Algebra**

The table below represents the function f(x). (-6, 12),(-5,-8),(-4,-4), (-3,0),(-2,4),(-1,8),(0,12). If g(x) is a linear function that has a slope of -3 and a y-intercept of -9, which statement is true? A) The x-intercept of f(x) is less than the x-intercept of g(x). <<&...

*May 21, 2014*

**Cost Accounting**

A company’s sales volume averages 4,000 units per year. Recently, its main competitor reduced the price of its product to $48. The company expects sales to drop dramatically unless it matches the competitor's price. In addition, the current profit per unit must be ...

*May 20, 2014*

**Chemistry**

When 155 mL of water at 26 degrees Celsius is mixed with 75 mL of water at 95 degrees Celsius, what is the final temperature of the mixture? (d Water = 1.00 g/mL) Im really stuck on this problem and chemistry isnt exactly my strong point, thanks in advance!

*May 19, 2014*

**physicss**

a point charge -q, mass m is flying up at the speed v(0)= v 0 from the distance x(0)=L from a uniformly and positively charged thin plate, its linear density equal p. determine the maximum distance of a particle from the plate

*May 19, 2014*

**Physics**

a point charge -q, mass m is flying up at the speed v(0)= v 0 from the distance x(0)=L from a uniformly and positively charged thin plate, its linear density equal p. determine the maximum distance of a particle from the plate

*May 19, 2014*

**Astronomy**

v = c*sqrt(1-4/a) a = 4/θ^2 θ = sqrt(4/a) inverse formula sqrt(1-v/c^2), so in this case. v = c*sqrt(1-4/a)

*May 11, 2014*

**algebra**

Let f(x)= 2x^2 +7 and g(x)= x – 6. (a) Find the composite function (f*g)(x) and simplify. Show work. (b) Find ( f*g)(1). Show work.

*May 9, 2014*

**Pre algebra**

A cyclist rides her bike at a speed of kilometers per hour. What is this speed in kilometers per minute? How many kilometers will the cyclist travel in minutes? Do not round your answers.

*April 26, 2014*