Thursday

February 23, 2017
Total # Posts: 8,248

**math-linear algebra**

Determine the standard matrix D of the linear mapping G: R^2--R^2 that first rotates points clockwise through pi/6 radians and then reflects points through the line x_2=x_1

*November 11, 2015*

**Physics**

Air consists of molecules of several types, with an average molar mass of 28.95g. About how many molecules does an adult who inhales 0.50L of air at sea level take in? The answer should be 1.3x10^22

*November 11, 2015*

**math**

2x - 6 = 20. Add 6 to both sides. 20 + 6 = 26 26÷2 =13

*November 11, 2015*

**math**

[2(X+26)]/2=264/2 X+26=132 X+26-26=132-26 X=106

*November 11, 2015*

**physics**

A puck (mass m1 = 2.20 kg) slides on a frictionless table as shown in the figure below. The puck is tied to a string that runs through a hole in the table and is attached to a mass m2 = 6.6 kg. The mass m2 is initially at a height of h = 6.6 m above the floor with the puck ...

*November 10, 2015*

**physics**

A child of mass 52 kg jumps onto the edge of a merry-go-round of mass 170 kg and radius 1.9 m that is initially at rest as sketched in the figure below. While in the air (during her jump), the child's linear velocity in the direction tangent to the edge of the merry-go-...

*November 10, 2015*

**physics**

The drawing shows a skateboarder moving at 6.88 m/s along a horizontal section of a track that is slanted upward by 37.3 ° above the horizontal at its end, which is 0.741 m above the ground. When she leaves the track, she follows the characteristic path of projectile ...

*November 9, 2015*

**Organic Chemistry 2**

What is the impurity that must be removed from the benzaldehyde reagent before it can be used in this experiment? this is from are Benzil lab

*November 9, 2015*

**Organic Chemistry 2**

Compare the IR spectrum of benzoin ) with the IR spectrum of benzil . Explain how the changes in the important peaks are related to the differences between the two structures.

*November 9, 2015*

**math**

Every cereal box has a gift inside, but you cannot tell from the outside what the gift is. The store manager assures you that 16 of the 58 boxes on the shelf have the secret decoder ring. The other 42 boxes on the shelf have a different gift inside. If you randomly select two ...

*November 8, 2015*

**math**

In a family with 4 children what is the probability of having 1 boy and then 3 girls, in that order? (Exclude multiple births and assume all outcomes are equally likely). In a family with 4 children, what is the probability of having 1 boy and 3 girls, in any order? (Exclude ...

*November 8, 2015*

**math**

A hacker is trying to guess someone's password. The hacker knows (somehow) that the password is 14 characters long, and that each character is either a lowercase letter, (a, b, c, etc), an uppercase letter (A, B, C, etc) or a numerical digit (0, 1, 2, 3, 4, 5, 6, 7, 8, or ...

*November 8, 2015*

**math**

A hacker is trying to guess someone's password. The hacker knows (somehow) that the password is 14 characters long, and that each character is either a lowercase letter, (a, b, c, etc), an uppercase letter (A, B, C, etc) or a numerical digit (0, 1, 2, 3, 4, 5, 6, 7, 8, or ...

*November 8, 2015*

**math**

A couple plans to have three children. What is the probability that. a) they have all boys? b) they have at least one girl?

*November 8, 2015*

**Organic Chemistry 2**

What is the impurity that must be removed from the benzaldehyde reagent before it can be used in this experiment? this is from are Benzil lab in this lab, benzoin condensation of benzaldehyde will be carried out with a biological coenzyme, thiamine hydrochloride, as the ...

*November 8, 2015*

**Organic Chemistry 2**

What is the purpose of adding NaOH ot the reaction? This is the from our Benzil Lab.

*November 8, 2015*

**Organic Chemistry 2**

Compare the IR spectrum of benzoin ) with the IR spectrum of benzil . Explain how the changes in the important peaks are related to the differences between the two structures.

*November 8, 2015*

**Organic Chemistry 2**

Compare the IR spectrum of benzoin ) with the IR spectrum of benzil . Explain how the changes in the important peaks are related to the differences between the two structures.

*November 7, 2015*

**Organic Chemistry 2**

What is the purpose of adding NaOH ot the reaction? This is the from our Benzil Lab.

*November 7, 2015*

**Organic Chemistry 2**

Isolation of crude Benzoind-allow about 5 minutes for the crystals of benzoin to form fully. place the flask, with crystals, into an ice bath for 5-10 minutes. Break up the crystalline mass with a spatula, swirl the flask rapidly and quickly transfer the benzoin to a hirsch ...

*November 7, 2015*

**Organic Chemistry 2**

Procdure. Reaction Mixture-Add 0.3 g of thiamine hydrochloride to a erlenmeyer flask. Dissolve the solid in 0.45 mL of water by swirling the flask. Add 3.0 mL of 95% ethanol, and swirl the solution until it is homogeneous. To this solution add 0.9 mL of an aqueous sodium ...

*November 7, 2015*

**Organic Chemistry 2**

umm in this lab, benzoin condensation of benzaldehyde will be carried out with a biological coenzyme, thiamine hydrochloride, as the catalyst:

*November 7, 2015*

**Organic Chemistry 2**

What is the impurity that must be removed from the benzaldehyde reagent before it can be used in this experiment? this is from are Benzil lab

*November 7, 2015*

**Physics**

The propeller blades of an airplane are 2.4 m long. The plane is getting ready for takeoff, and the propeller starts turning from rest at a constant angular acceleration. The propeller blades go through two revolutions between the fifth and the seventh second of the rotation. ...

*November 7, 2015*

**Math**

9/16 x 2/3 =

*November 5, 2015*

**math 8th grade**

for a project, you need the diagonal fold of a square piece of origami paper to be 10 cm long. to what dimensions do you need to cut the square origami paper?

*November 5, 2015*

**math 8th grade**

a black 8" tile was cut to surround a white 8" tile. what is the perimeter of the design?

*November 5, 2015*

**math 8th grade**

what is the height of an equilateral triangle with an edge of one meter?

*November 5, 2015*

**calculus**

An Olympic athlete is standing at the edge of one side of a 3.7km wide river and wants to reach the point 7.4km downstream just along the edge of the opposite side. For this entire 7.4km stretch, the river is completely straight. The velocity of the current is negligible. The ...

*November 5, 2015*

**Math! Pls Help!**

i need help on that same thing can you put something els up

*November 5, 2015*

**Biology**

0.052

*November 5, 2015*

**chemistry**

To a 100.0 mL solution containing 0.0100 M Ba(NO3)2 and 0.0100 M Pb(NO3)2 was added 101.0 mL of 0.0100 M H2SO4 to provide a slight excess of SO42- relative to Ba2+ in the resulting solution. Assuming that: i) H+ does not bind to SO42- ii) ionic strength effects can be ignored ...

*November 4, 2015*

**Physics**

The propeller blades of an airplane are 2.4 m long. The plane is getting ready for takeoff, and the propeller starts turning from rest at a constant angular acceleration. The propeller blades go through two revolutions between the fifth and the seventh second of the rotation. ...

*November 4, 2015*

**Calculus**

For a cylinder with a surface area of 90, what is the maximum volume that it can have? Round your answer to the nearest 4 decimal places. The volume of a cylinder is πr^2*h and the surface area is 2πrh+2πr^2.

*November 4, 2015*

**physics**

You drop a 1.90 kg book to a friend who stands on the ground at distance D = 11.8 m below with outstretched hands at distance d = 1.42 m above the ground. a)What is the speed of the book when it reaches the hands? b)If we substituted a second book with twice the mass, what ...

*November 3, 2015*

**Algebra 1**

Did you ever find out the answer?

*November 3, 2015*

**Math**

a wrench is dropped by a worker at a construction site. four seconds later the worker hears it hit the ground below. How high is the worker above the ground? (The velocity of sound is 1100 ft/s, and the distance the wrench falls as a function of time is s=6t^2

*November 2, 2015*

**physics**

a block of mass M = 9.9 kg rests on a bracket of mass m = 5.5 kg. the bracket sits on a frictionless surface. the coefficients of friction between the block and the bracket on which it rests are .4 and .3. what is the maximum force that can be applied if the block is not to ...

*November 2, 2015*

**science**

Ana exerts a force of 20 N on a volleyball that has a mass of 0.15 kg. What is the force that the volleyball exerts on Ana?

*November 2, 2015*

**biology**

Determine the effective population size of the current population located on an island. You conduct a census and determine there are about 1500. -Your initial survey indicated that there are 500 juveniles (Smaller, with no horns) on the island. What would you consider the ...

*October 31, 2015*

**Physical science**

Mist graph

*October 29, 2015*

**math**

Ms.Sue can you help me

*October 28, 2015*

**math**

@Ms.Sue

*October 28, 2015*

**math**

what is 10 5/18 - 8 5/6 A. 2 5/9 B. 2 13/18 C.1 4/9 d. 1 11/18 I think It is B?

*October 28, 2015*

**Physics**

When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees upon landing to reduce the force of the impact. A 69.3-kg man just before contact with the ground has a speed of 6.94 m/s. (a) In a stiff-legged ...

*October 28, 2015*

**maths**

Fence post are placed 3m apart from each other. How many posts will be placed over a distance of 45m?

*October 27, 2015*

**business statitics**

a) The mean lifetime of a sample of 100 light tubes produced by a company is found to be 1570 hours with standard deviation of 80 hours. Test the hypothesis that the mean lifetime of the tubes produced by the company is 1600 hrs. (7 marks)

*October 27, 2015*

**math**

Find the values of the trigonometric function cot -8/17 sin: sec: tan: cot: I know you use a Pythagorean Identity, sin^2t + cos^2t=1 I got 64/289 for the first one for example and it was wrong.

*October 26, 2015*

**Calculus**

A force of 6 pounds is required to hold a spring stretched 0.2 feet beyond its natural length. How much work (in foot-pounds) is done in stretching the spring from its natural length to 0.6 feet beyond its natural length? could you please explain how. thanks

*October 26, 2015*

**chem - help!**

Different manufacturers claim to have the best antacid. Which of the following tablets would neutralize the most acid for the money? Write a balanced chemical equation along with your answer. a) Rolaids (550 mg CaCO3 and 110 mg Mg(OH) per tablet) - 150 tablets for $9.44 b) ...

*October 26, 2015*

**vectors linear algebra**

The parametric equations for a line L1 are as follows: x = −4−6t y = 2+2t z = 1−4t Let L2 be the line parallel to L1 and passing through the point (−3, −3, −3). Find the point P on L2 whose x-coordinate is −12. P=P(-12, _ , _ ) ?

*October 26, 2015*

**math**

find the sum of the sequence 41+42+43+44+117

*October 25, 2015*

**chem**

Different manufacturers claim to have the best antacid. Which of the following tablets would neutralize the most acid for the money? Write a balanced chemical equation along with your answer. a) Rolaids (550 mg CaCO3 and 110 mg Mg(OH) per tablet) - 150 tablets for $9.44 b) ...

*October 25, 2015*

**physics**

17 23

*October 25, 2015*

**biology**

Which of the following statements best explains the relationship between the mitochondria and the plasma membrane? A. The mitochondria makes proteins that become a part of the plasma membrane. B. The mitochondria makes a gas that the plasma membrane uses. C. The mitochondria ...

*October 25, 2015*

**science**

im confused are these answers incorrect ?

*October 25, 2015*

**math**

1)11.7 so do you round up or no ? either its 11 or 12 2)87.50 ? 3)A

*October 25, 2015*

**math**

6.85 ?

*October 25, 2015*

**math**

Suppose f(t) is the weight (in grams) of a solid sitting in a beaker of water and the solid is dissolving at a rate (in grams/minute) of f'(t)=-4 f(t)(3 + f(t) ). If there is 4 grams of solid at time t=2 minutes, use a linear approximation to estimate the solid's ...

*October 24, 2015*

**math**

Suppose f(t) is the weight (in grams) of a solid sitting in a beaker of water and the solid is dissolving at a rate (in grams/minute) of f'(t) =-4 f(t)(3 + f(t) ). If there is 4 grams of solid at time t=2 minutes, use a linear approximation to estimate the solid's ...

*October 24, 2015*

**math**

Suppose N(t) denotes a population size at time t where the dN/dt=0.03 N(t). If the population size at time t=4 is equal to 100, use a linear approximation to estimate the size of the population at time t=4.1.

*October 24, 2015*

**math**

A cup of coffee at 173 degrees is poured into a mug and left in a room at 72 degrees. After 6 minutes, the coffee is 137 degrees. Assuming that Newton's Law of Cooling applies: After how many minutes will the coffee be 100 degrees?

*October 24, 2015*

**math**

Suppose f(x)=ln x. (a) Find the linear approximation of f at a=1. L(x)= (b) Use the linear approximation to estimate ln 1.27. ln1.27=

*October 24, 2015*

**Chemistry**

Do positive ions or the negative ions cause the change in flame color ? Explain why and give on example.

*October 23, 2015*

**Reading: Paricia A. Ackerman**

Gudnite!

*October 23, 2015*

**Reading: Paricia A. Ackerman**

Dinner Together : Sitting by the barbecue waiting for sausages and hot dogs blue-gray smoke the same color of the sky I see a tiny spider walking down from the sky with tiny six footed steps down down in a perfectly straight line all the way down to the floor then back up the ...

*October 23, 2015*

**Reading: By Houghton Mifflin**

On page 241 Focus on Poetry Animals Dinner Together: sitting by the barbecue waiting for sausages and hot dogs blue-gray smoke the same color of the sky I see a tiny spider walking down the sky with tiny six footed steps down down in a perfectly straight line all the way down ...

*October 23, 2015*

**Reading**

Poetry animals dinner together. What is all about? Page 241

*October 23, 2015*

**math**

john has 24 baseball cards. chard has 13 more cards than john. draw a comparison problem to illustrate how to solve the problem, then slove

*October 20, 2015*

**Math**

3x+3(x-1)<-18

*October 20, 2015*

**Marh**

The nearest sq mile would be a whole number, so round to the nearest whole number. (the place for the decimal). I am assuming the value you stated is in square miles.

*October 20, 2015*

**Math**

When the problem says "about" it sounds like they are looking for an estimate. A good estimate would be to multiply 6 times 700 to get 4200.

*October 20, 2015*

**Counting and Probability**

Any 2-digit number with a 1 is special (and all special numbers have at least one 1). There are nine 2-digit numbers with ones digit 1, and, there are nine additional 2-digit numbers with tens digit 1 (except from 11, which we've already counted, since its ones digits is ...

*October 20, 2015*

**Math**

Could the 1.5 miles take him farther because it said across and not around the loop? There might be another 1.5 to add to the total. Not sure...

*October 20, 2015*

**maths**

In general, distance = rate x time This case: distance = (rate + current) x time distance = (rate - current) x time 100 = (50 -c)(t) 100 = (50+c) (t + 3 3/4 minutes) This should get you started.

*October 20, 2015*

**physcial science**

B moving electric charges cause a magnetic field to form.

*October 20, 2015*

**Math**

multiply the 7.5 times 3 to give you 22.5 times 10^-5 To get to standard notation you need to write the 22.5 as 2.25 x 10^1 combine the 1 + -5 to get -4 because we have the same base of 10. When multiplying, you keep the base and add the exponents. 2.25 x 10^-4

*October 19, 2015*

**physics**

32 m/sec will be decreased at for 3.0 sec. 32-12 = 20 m/s 4.0 m/sec times 5.25 sec. = 21 m/sec 1m/sec faster. b) d= rt You could use the average rate by computing the beginning and ending speeds

*October 19, 2015*

**Geometry**

yes!

*October 19, 2015*

**math Help Azap!!!**

To solve for a, we first have to remove the ( ) 9a -3a +18 = -6 6a + 18 = -6 Can you finish from here? Be sure to check your answer in the original equation.

*October 19, 2015*

**Algebra**

1) 7(3) = -56(33y) 7(3)/ (-56)(33) = y 2) (8)(44) = (29)(11k) (8)(44)/(29)(11) = k Can you finish from here? You can make the math a little simpler by cancelling.

*October 19, 2015*

**Math**

divide both sides by -4 which causes you to flip the sign...you have the sign correct, but it should be a 3 The first choice. Every set is a subset of itself, so it should be the last choice.

*October 19, 2015*

**algebra**

It looks like k = -2 because 3x times -2 = -6x and -2 times -2 = 4

*October 19, 2015*

**English**

What literary device is being used in this passage? "'See!' he cried triumphantly. 'It's a bona-fide piece of printed matter. It fooled me. This fella's a regular Belasco. It's a triumph. What thoroughness! What realism! Knew when to stop, too--...

*October 18, 2015*

**Adamson University Math**

Klasmeyt may sagot ka na dyan? naghahanap din po ako eh.. need help po :)

*October 15, 2015*

**geomtry**

two angles form a linear pair the measure of one angle is 24 more than the measure of the the other anglr

*October 15, 2015*

**Math**

A lock has 3 tumblers each has 10 numbers from one through zero, how many possibilities to open lock and what are the numbers ?

*October 14, 2015*

**Math**

Typo 1/12

*October 14, 2015*

**Math**

12 marbles total 3/12 times 3/12 if you are replacing it. 1/4 times 1/4 = 1/16 There are 6 possible outcomes. 1/6 to roll a three and 3/6 to roll an even number. For both to happen you have 1/6 times 1/2

*October 14, 2015*

**algebra**

2x + 3y = 1470 Slope intercept form is y = mx+b So you want to solve for y: subtract 2x from both sides and divide by 3. 3y = -2x +1470 y = -2/3 x + 1470/3 or y = -2/3x +490 To graph you would start at the point (0,490) and to find the next point you would use -2/3 = change in...

*October 14, 2015*

**Physics**

A golf ball strikes a hard, smooth floor at an angle of 20.7 ° and, as the drawing shows, rebounds at the same angle. The mass of the ball is 0.0528 kg, and its speed is 40.2 m/s just before and after striking the floor. What is the magnitude of the impulse applied to the ...

*October 14, 2015*

**Math**

It is -9 sorry about the typo.. I am glad Ms. Sue caught that.

*October 12, 2015*

**Math**

Simplify like terms which means to combine the 10h -5h which is 5h 9 + 5h = 0 subtract 9 from both sides 5h = 9 Divide by 5 to get h = 9/5

*October 12, 2015*

**Math**

Here is a nice website that shows steps that you asked for in #4 - I am not allowed to post it. Do a google search of solving linear equations and look for one related to NYS regents. If you can solve for the variable, the equation is open. If you eliminate all of the ...

*October 12, 2015*

**Math**

projectile hits the ground when s(t) = 0 meaning the height off the ground is zero. 0 = 144t -16 t^2 Factor out the t: 0 = t(144 -16t) set each part = to zero t = 0 the projectile wasn't launched yet and 144- 16t = 0 solve for t to find out how long the projectile was in ...

*October 12, 2015*

**physics**

A 56-kg rollerblader skates across a skating rink floor. The graph below shows the net external force component F cos è along the displacement as a function of the magnitude of the displacement d. Determine the Following: (a) work done by the net force component F cos &...

*October 12, 2015*

**statistics**

17 balls total There are 10 red 10/17 is your chance.

*October 12, 2015*

**math**

For #4, you are subtracting 1 from each part and not adding it. subtracting 1 gives you 2x = 10 and 2x = -12 You had the right idea, but the adding 1 is wrong, you really subtracted 1. Teacher was probably looking for you to show the adding 8 and dividing by 4 and for the ...

*October 12, 2015*

**Math**

When you solve the equations, you will find that when the letters (variables) are eliminated you will be left with a number on each side of the equal sign. If they numbers are the same, you have and identity. If not, it is not an identity.

*October 12, 2015*

**Physics**

12.13m

*October 12, 2015*