# Posts by tom

Total # Posts: 1,408

**physics**

A 1093 kg van, stopped at a traffic light, is hit directly in the rear by a 715 kg car traveling with a velocity of +2.38 m/s. Assume that the transmission of the van is in neutral, the brakes are not being applied, and the collision is elastic. What is the final velocity of ...

*February 26, 2012*

**CHEM**

2) we know that gold is the thing we want.so use a method to have reaction with zinc but not gold. Hydrochloric acid is a good example. then use filter and filter paper to filter the gold out 3)AgCl is insoluble in water which is white in colour.its the white precipitate

*February 26, 2012*

**physics**

A 2.80 kg steel ball strikes a massive wall at 12.8 m/s at an angle of alpha = 50.9° with the plane of the wall. It bounces off with the same speed and angle. If the ball is in contact with the wall for 0.156 s, what is the magnitude of the average force exerted on the ...

*February 24, 2012*

**physics**

Two men pushing a stalled car generate a net force of +698 N for 7.37 s. What is the final momentum of the car?

*February 23, 2012*

**American History**

C is the best answer

*February 23, 2012*

**Chemistry**

21.6

*February 22, 2012*

**biology**

Which nutrient functions BOTH as an enzymatic cofactor and as a stabilizer of ribosomes and nucleic acids? a) potassium b) phosphorus c) calcium d) Magnesium Thanks for your help!!

*February 20, 2012*

**physics**

A 690 kg elevator starts from rest. It moves upward for 2.56 s with constant acceleration until it reaches its cruising speed, 1.84 m/s. What is the average power of the elevator motor during this period? What is the power of the elevator motor during an upward cruise with ...

*February 20, 2012*

**geometry**

what equation represents the relationship of perimeter of a square varies directly as the length of it's side ?

*February 18, 2012*

**pennfoster**

Which of the following sentences contains a verb in the simple past tense? A. I was working overtime for about six months. B. She would like to join us. C. We helped Joan to pack her things. D. Jenna has driven this route multiple times

*February 15, 2012*

**Physics**

Hillary stands directly in front of speaker S1 and walks straight away (down on the page) What is the first distance (measured from S1) at which she will hear minimum loudness? Speed of sound is 341 m/s and the frequency of the sound is 496 Hz. The speakers are 2.07 m apart. ...

*February 9, 2012*

**chemistry**

the amount of heat when 65g of water at 100c until it cools to 37c

*February 1, 2012*

**Physics**

For finding Power, that's where I'll use 13kJ / 37,83 sec. right? = 343.64 watts.

*January 31, 2012*

**Physics**

so I was supposed to do Fres. X distance for 1 J = 1N*m. I had mixed the previous formulas up, I had the W for watts instead of Work. So my final answer for the work of the air resistance is actually 26N*500m = 13,000 J or 13 kJ. is that correct?

*January 31, 2012*

**Physics**

I just wanted to be sure if I got the answer right 1. Jenny (75 kg) goes on a ski trip. She goes down a slope that's inclined at 15*. Her drag coefficient is 0.300, the area of contact with the air is 0.750 m^2 and the air density is 1,31 kg/m^3. The coefficient of kinetic...

*January 31, 2012*

**chemistry**

A 100.0 gram sample of iron at 80.0 degrees Celsius was placed in 150 grams of water at 20.5 degrees Celsius. What was the final temperature when thermal equilibrium was reached?

*January 31, 2012*

**chemistry**

At 22 degrees Celsius and a pressure of 755 mm Hg, an unknown gas was found to have a density of 4.52 g/L. When analyzed, the gas was found to consist of two elements: Boron at 78.1% and Hydrogen at 21.9%. What is the molecular formula of this unknown gas?

*January 31, 2012*

**Physics**

Wrote the name and subject bad in the other post, sry:: Hello, this is the last question that I can't seem to be able to solve: 1. Jenny (75 kg) goes on a ski trip. She goes down a slope that's inclined at 15*. The drag coefficient of Jenny is 0.300, the surface of ...

*January 27, 2012*

**calculus**

Let f(x)=(x^2)+x+14. What is the value of f(x) for which the tangent line to the graph of y=f(x) is parallel to the x-axis?

*January 26, 2012*

**Algebra 2**

Dawn is writing a computer program to find the salaries of her employees after their annual raise. The percentage of increase is represented by p in the program. Marty's salary is $23,450 now. Write a polynomial to represent Marty's salary in one year and one to ...

*January 12, 2012*

**physics**

A particle is displaced from the point ( 4 m, 12 m ) to the point ( 9 m, 1 m ) in 30 seconds. Calculate the direction (with respect to the positive x axis) of its average velocity vector.

*December 30, 2011*

**math**

29x47

*December 29, 2011*

**math**

For tax purposes, business frequently depreciate equipment.

*December 16, 2011*

**Physics2**

ok thank you drwls!

*December 9, 2011*

**Physics**

2 blocks are in contact on a horizontal table. A force is applied on the first block at a 30* angle. The blocks move to the right side. If m1 = 2kg and m2 = 1kg and F = 6 N kinetic friction at the middle of the 2 blocks and the table = 0.250 Find the "contact force" ...

*December 8, 2011*

**MATH**

the figure shows that the angle of elevation to the top of the building changes from 20 degree to 40 degree as an observer advances 75 feet toward the building. Find the height of the building to the nearest feet.

*December 6, 2011*

**math**

List at least one way in which a scalene triangle and equilateral triangle are the same.

*November 30, 2011*

**math**

List at least one way in which an acute triangle and an obtuse triangle are different.

*November 30, 2011*

**Physics**

v = fλ 23 m/s = 82Hz * λ λ = 23/82 λ = 0.28048780498 meters apart This one is correct

*November 21, 2011*

**Physics**

v = fλ 23 m/s = 84Hz * λ λ = 23/82 λ = 0.28048780498 meters apart

*November 21, 2011*

**Physics**

v = fλ 23 m/s = 84Hz * λ λ = 23/84 λ = 0.2738095238 meters apart

*November 21, 2011*

**Physics**

A car driving along a highway at a speed of 23 m/s strays onto the shoulder. Evenly spaced parallel grooves called “rumble strips” are carved into the pavement of the shoulder. Rolling over the rumble strips causes the car's wheels to oscillate up and down at a ...

*November 21, 2011*

**Chemistry**

a real gas would behave most like an ideal gas under conditions of

*November 18, 2011*

**pre algebra**

my numerator is a prime number My denominator is divisible by 2 i am equivalent to 1/5

*November 16, 2011*

**Chemistry**

What is the trend in atomic size in the series of Group IIA elements Be through Ra?

*November 14, 2011*

**Physics**

A record has an angular speed of 47 rev/min. Through what angle does it rotate in 1.07 s? Answer in units of ra

*November 11, 2011*

**Excel-Exponential Fits**

Hey Im trying to plot this set of data: 0 0 10 0.6 20 1.01 30 1.428 40 2 50 2.3 60 2.57 70 2.8 80 3.05 90 3.35 100 3.54 110 3.73 120 3.9 130 4.08 140 4.25 150 4.39 160 4.53 170 4.65 180 4.754 190 4.846 200 4.943 210 5.011 220 5.111 230 5.175 240 5.23 250 5.295 260 5.356 270 5....

*November 11, 2011*

**Calculus (2)**

oh I get it now, tnx!

*November 11, 2011*

**Calculus (2)**

and how do you get (x+1)?

*November 11, 2011*

**Calculus (2)**

Tnx for the quick answer, but I still have a question: why is it - in y' = e^-x (-) (x+2)e^-x instead of a + ?

*November 11, 2011*

**Calculus (2)**

find the first and second derivative of: f(x) = (x+2)/e^x I get to: f'(x) = e^x - (x+2)(e^x) / (e^x)^2 I'm stuck at that

*November 11, 2011*

**calculus**

last one is supposed to be dy/dx = 1 / ((e^y^2 * 3y^2) - (9^xsin(3y)ln3) - (1+3y))

*November 11, 2011*

**calculus**

considering that x is the independent variable in this equation: y + y^3 + 3 = e^y^2 + 3^x * cos(3y) - x Evaluate dy/dx I get to: dy/dx (1+3y) = e^y^2 * 3y^2 * dy/dx + 3^x * ln3 * (-sin(3y)) * 3 *dy/dx -1 Will it give me? dy/dx(1+3y) = dy/dx((e^y^2 * 3y^2) + (3^x * ln3 * (-sin...

*November 11, 2011*

**Organic Chemistry**

What is the mechanism for the removal of bromine from dibromocholesterol using Zinc and acetic acid?

*November 9, 2011*

**Math**

In Mrs Halls class of 30 students, 17 have computers at home and 20 have cassettes. If 4 students in the class have neither a computer or a cassette, how many of the 30 students have both?

*November 7, 2011*

**Maths**

Calculate speed give your answers in km/p hour Distance = 18 KM Time = 12 minutes S - T

*November 6, 2011*

**Physics**

In Fig. 6-34, blocks A and B have weights of 46 N and 23 N, respectively. (a) Determine the minimum weight of block C to keep A from sliding if μs between A and the table is 0.21. (b) Block C suddenly is lifted off A. What is the acceleration of block A if μk between...

*October 23, 2011*

**Physics**

A student, crazed by final exams, uses a force of magnitude 86 N and angle θ = 61° to push a 5.2 kg block across the ceiling of his room, as in Figure 6-52. If the coefficient of kinetic friction between the block and the ceiling is 0.34, what is the magnitude of the ...

*October 23, 2011*

**Physics**

A warehouse worker exerts a constant horizontal force of magnitude 89.0 N on a 43.0 kg box that is initially at rest on the horizontal floor of the warehouse. When the box has moved a distance of 1.60 m, its speed is 1.10 m/s. What is the coefficient of kinetic friction ...

*October 23, 2011*

**Physics**

A warehouse worker exerts a constant horizontal force of magnitude 89.0 N on a 43.0 kg box that is initially at rest on the horizontal floor of the warehouse. When the box has moved a distance of 1.60 m, its speed is 1.10 m/s. What is the coefficient of kinetic friction ...

*October 23, 2011*

**Physics**

A 3.4 kg block is pushed along a horizontal floor by a force of magnitude 21 N at a downward angle θ = 40°. The coefficient of kinetic friction between the block and the floor is 0.26. What the magnitude of the block's acceleration?

*October 23, 2011*

**college physics**

A 0.384 kg puck, initially at rest on a horizon- tal, frictionless surface, is struck by a 0.189 kg puck moving initially along the x axis with a speed of 2.7 m/s. After the collision, the 0.189 kg puck has a speed of 1.7 m/s at an angle of 28 to the positive x axis. ...

*October 22, 2011*

**physics**

A 2200 kg car is travelling at 45 km per hour when its brakes are applied and it skids to a stop. If the coefficient of friction between the road and the tires is 0.70 how far does the car go before stopping?

*October 18, 2011*

**algebra world problems**

1+1

*October 17, 2011*

**PHYSICS HELP PLEASE!**

Here is how it is phased in the question: (2) The orbiting space shuttle moves around the Earth well above 99% of the atmosphere, yet it still accumulates an electric charge on its skin due (in part) to the loss of electrons caused by the photoelectric effect from sunlight. ...

*October 13, 2011*

**PHYSICS HELP PLEASE!**

The maximum wavelength of light emitted from a blackbody that will emit electrons from a given piece of metal is 255nm. What is the fraction of total energy emitted from the black body that emits electrons? I set up the integral: Int(8πhcλ^-5)/(e^(hc/λkT)-1)) ...

*October 13, 2011*

**physics**

A piece of copper is made into a rod with a square cross-section. The side of the square is 2.00 centimeters. The resistivity of copper is 1.7 \cdot 10^{-8} \Omega\cdot {\rm m}. An unknown electric field E, directed along the rod, creates a current of 12.0 amperes through the ...

*October 10, 2011*

**PHYSICS**

In a particular region of Earth's atmosphere, the electric field above Earth's surface has been measured to be 151 N/C downward at an altitude of 280 m and 167 N/C downward at an altitude of 430 m. Calculate the volume charge density of the atmosphere, assuming it to ...

*October 10, 2011*

**Physics**

An infinitely long line charge of uniform linear charge density λ = -3.00 µC/m lies parallel to the y axis at x = -2.00 m. A point charge of 4.70 µC is located at x = 1.50 m, y = 2.50 m. Find the electric field at x = 2.50 m, y = 2.00 m. I added the vectors, ...

*October 10, 2011*

**Physics**

In a particular region of Earth's atmosphere, the electric field above Earth's surface has been measured to be 151 N/C downward at an altitude of 280 m and 167 N/C downward at an altitude of 430 m. Calculate the volume charge density of the atmosphere, assuming it to ...

*October 9, 2011*

**algebra**

9/10Y = 36 What is Y

*October 6, 2011*

**s.s**

how does gps works

*October 5, 2011*

**math**

This is a quadratic equation where perimeter is only 3 sides so p=l x 2w and if width is x then side is 2000-2x then area = x(2000-2x) = 2000x-2x^2 the vertex of this parabola will be x=500 and length is 1000 for area=500000 calculus derivative =2000-4x=0 for max-min point and...

*October 3, 2011*

**Chemistry**

The solubility of a certain compound in ice-cold water is 0.22g in 100mL. Its solubility in hot water is 4.35g in 100mL What is the best possible percent recovery we can expect for the re-crystallization of this compound in water?

*September 29, 2011*

**chem**

why are electron groups that repel each other higher in energy?

*September 25, 2011*

**physics**

yes

*September 21, 2011*

**Statistics**

Find the numerical value of k: -2.35=[(k-100)/15]

*September 21, 2011*

**statistics**

Based on data collected by the National Center for Health Statistics and made available to the public in the Sample Adult database, an estimate of the percentage of adults who have at some point in their life been told they have hypertension is 23.53 percent. If we select a ...

*September 13, 2011*

**math**

decimal value for 1/11

*September 12, 2011*

**Math**

angel m1 =125 dagrees angek m2= ?

*September 7, 2011*

**chemistry**

If the density of a certain alcohol is 0.785 g/mL, what volume of the alcohol would have a mass of 75.0g?

*September 2, 2011*

**spelling**

how do you make a spelling triangle

*August 31, 2011*

**finance**

$63,584.00is the correct answer. $80 x 5.68 = 454.40 454.40 x 360 = 163,584.00 163,584.00 - 100,000 = $63,584.00 D.) $63,584.00

*August 31, 2011*

**physics**

A car travels along a straight stretch of road. It proceeds for 15 mi at 55 mi/h, then 29 mi at 43 mi/h, and ﬁnally 37.9 mi at 33.7 mi/h. What is the car’s average velocity during the entire trip? Answer in units of mi/h

*August 23, 2011*

**chemistry**

Calculate the percent yield if 104 g of CH3CO2CH2CH3 is produced by the reaction of 111 g of CH3CO2H according to the following equation: CH3CO2H(l) + CH3CH2OH(l) ¨ CH3CO2CH2CH3(l) + H2O(l)

*August 14, 2011*

**Statistics**

I have recently administered an employee survey at a call center. I found a Pearson r of -.66 between the employees' ages and their scores on an employee engagement scale. What does this finding represent/mean? Also, there is a relationship between gender and employee ...

*August 5, 2011*

**chemistry**

Given that ΔHof of copper (II) chloride, CuCl2(s), is –220.1/kJ and ΔHof of copper (I) chloride, CuCl(s), is –137.2 kJ, calculate ΔHo for the reaction when 14.0 g of copper is used: CuCl2(s) + Cu(s) → 2 CuCl(s)

*August 3, 2011*

**statistics**

Consider the average available for all hotel rooms from the previous assignment. Identify the point estimate of the average number of available hotel rooms in this lesson from each sample. Construct and Interpret a 95% confidence level for the true mean number of available ...

*August 2, 2011*

**Chemistry**

I don't agree this answer. number %khp so high

*July 31, 2011*

**physics**

a student tries to open a door at a distance of 1 cm from the hinge at a distance of 10 cm from the hinge and at a distance of 50 cm from the hinge why is a larger force required at 1 cm than at 50 cm?

*July 23, 2011*

**telemarketing**

A telemarketer with B2B Communications has a 20 percent historical probability of making a sale during a shift where 100 calls were made. Assign a random variable x, where the value of x is equal to the number of sales made during the shift. Describe the probability ...

*July 23, 2011*

**statistic**

The average score on a standardized test is 750 points with a standard deviation of 50 points. If 2,000 students take the test at a local school, how many students do you expect to score between 700 and 800 points?

*July 21, 2011*

**statistics**

The average score on a standardized test is 500 points with a standard deviation of 50 points. What is the probability that a student scores between 450 and 600 on the standardized test?

*July 21, 2011*

**accounting**

A company has an overhead application rate of 125% of direct labor costs. How much overhead would be allocated to a job if it required total direct labor cost of $20,000? $5,000. $16,000. $25,000. $125,000. $250,000. The R&R Company's production costs for August are: ...

*July 16, 2011*

**geometry**

The diagonals of rhombus FGHJ intersect at point K. If side GH is equal to 3x - 10 and side JH is equal to 6x - 19, find x.

*July 14, 2011*

**English**

Does anyone know what this verse means: "shall summon to unwelcome bed"? Here is the full stanza of the poem. It is from through the looking glass? Come, hearken then, ere voice of dread, With bitter tidings laden, Shall summon to unwelcome bed A melancholy maiden! ...

*July 11, 2011*

**Algebra**

It is possible for a quadratic equation to have no real-number solutions:Solve : x2 + 5x + 3 = 0

*July 10, 2011*

**chem**

it dissolves

*July 9, 2011*

**algebra 2**

If Q varies inversely as the square root of R and Q=2 when R=4, what is Q when R is 25? does Q=625 im not sure can someone double check it for me.

*July 8, 2011*

**algrebra 2**

can someone please help me im stumped on these two. use analytical methods to solve the equation. 1+(1/x)=(42/x²) (7/x-4)=1+(9/x+4)

*July 8, 2011*

**algebra**

Solve using the substitution method. Show your work. If the system has no solution or an infinite number of solutions, state this. 4x + 4y = -36 4x + 4y = 12

*July 6, 2011*

**Chemistry**

For the reaction HNO3+HCl=NO2Cl+H20 What is the equilibrium constant at 25 C and 75 C

*July 1, 2011*

**statistics**

.099

*June 25, 2011*

**trig**

sinx+sinxcot^2x=cscx prove each identity

*June 24, 2011*

**trig**

tan(theta)-1= sin^2(theta)-cos^2(theta)/ sin(theta)cos(theta)+cos^2(theta) prove each identity

*June 24, 2011*

**Chemistry**

sulfur

*June 17, 2011*

**chemistry**

what is the volume of 4.4 moles of Cl2 at 285 kelvin and 0.87 atm. (R=0.0821 k*atm/mol*k)

*June 15, 2011*

**Math**

3(x-2)+4(2x-6)=6(x-4)+8(2x+1)x=

*June 11, 2011*

**Math**

What is the square root of 6 times the square root of 9 if there is no perfect square of 6

*May 23, 2011*

**english**

1890-1950 American MLA Format

*May 15, 2011*