# Posts by tom

Total # Posts: 1,423

**ALGERBRA**

Patricia owned so many posters that she decided to sell 63 of them to her friends. After selling the posters, she still had 172 left. Write and solve an equation to find the number of posters p Patricia had originally

**physics**

A mass m at the end of a spring vibrates with a frequency of 0.87 Hz. When an additional 602 g mass is added to m, the frequency is 0.59 Hz. What is the value of m?

**algebra**

Normally the largest area is enclosed by a square but this is only when the perimeter is 4 sides. In this problem the barn is the forth side with the 80 ft of fence used for only three sides. The complication is that the barn can contribute any lenght for its side. So the barn...

**geom/trig**

A 40 ft ladder leans against a wall so the base of the ladder is 11 feet away from the base of the wall . What angle does the ladder make with the wall?

**Math**

hello i need help for derivative: ( sin x ) / ( cos x ) thanks for your help

**chem 2**

What is the pH of a solution that consists of 0.50M H2C6H6O6(ascorbic acid) and 0.75M NaHC6H6O6(sodium ascorbate)? for ascorbic acid, Ka=6.8x10-5

**Stats**

Explain how to calculate margin of error. What effect does increasing your sample size have on the margin of error? What effect does it have on the confidence level? What effect does it have on the confidence interval?

**Statistics**

Explain how to calculate margin of error. What effect does increasing your sample size have on the margin of error? What effect does it have on the confidence level? What effect does it have on the confidence interval?

**physics**

A cylindrical object of volume V is immersed completely in a liquid. is the density of the object and L is the density of the liquid. Write the expression for the buoyant force on the object, using these terms.

**math**

Answer is b.50

**physics**

A 1289 Hz sound from the speaker enters a tube at point A. It then takes two paths, ACD or ABD. Minimum sound is heard when ACD has a length of 94.2 cm and ABD has a length of 41.0 cm. The length of ACD is slowly increased until the point of maximum loudness is found when ACD ...

**chemistry**

You are a chemist requested to review and analyse certain debris found on thebottom of aboot found in a crime scene. The debris contains metal fragments. If you identify the metal fragments---it will help the detctive identify the locations traveled by the person who did the ...

**chemistry**

a large 1.5 x 10^6liter tank contains water polluted with lead (II) nitrate at a molarity concentraion of 2.5 x 10^-6 M to the tank, you add 59.7 liters of 0.075 M potasium chloride solution. did you add enough potassium chloride to remove all the lead(II) ions out of the ...

**Spanish-Please check**

Thank you very much for correcting this-we're just learning this and I never thought it would be so difficult to do a conversation-thank you again

**Spanish-Please check**

Thank you for doing that

**Spanish-Please check**

We had to write a conversation in Spanish between a clerk and me wanting to buy pants I wanted them to be loose and I had to pay in cash Could you please check La dependienta: ¿En qué puedo servirle señor? La clienta: Busco los pantalones negro pero estos ...

**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 ...

**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

**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 ...

**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?

**American History**

C is the best answer

**Chemistry**

21.6

**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!!

**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 ...

**geometry**

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

**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

**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. ...

**chemistry**

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

**Physics**

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

**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?

**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...

**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?

**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?

**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 ...

**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?

**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 ...

**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.

**math**

29x47

**math**

For tax purposes, business frequently depreciate equipment.

**Physics2**

ok thank you drwls!

**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" ...

**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.

**math**

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

**math**

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

**Physics**

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

**Physics**

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

**Physics**

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

**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 ...

**Chemistry**

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

**pre algebra**

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

**Chemistry**

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

**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

**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....

**Calculus (2)**

oh I get it now, tnx!

**Calculus (2)**

and how do you get (x+1)?

**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 + ?

**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

**calculus**

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

**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...

**Organic Chemistry**

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

**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?

**Maths**

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

**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...

**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 ...

**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 ...

**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 ...

**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?

**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. ...

**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?

**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. ...

**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)) ...

**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 ...

**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 ...

**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, ...

**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 ...

**algebra**

9/10Y = 36 What is Y

**s.s**

how does gps works

**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...

**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?

**chem**

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

**physics**

yes

**Statistics**

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

**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 ...

**math**

decimal value for 1/11

**Math**

angel m1 =125 dagrees angek m2= ?

**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?

**spelling**

how do you make a spelling triangle

**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

**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

**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)

**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 ...

**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)

**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 ...

**Chemistry**

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

**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?

**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 ...

**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?

**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?

**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: ...