Wednesday

July 23, 2014

July 23, 2014

Total # Posts: 195

**chemistry**

Calculate the value of q for each of the experiments listed below. (Assume the heat capacity of water is 4.1801 J/g*C). Exp1: 2.48g of an unknown salt added to 160. mL of water resulted in a change of temperature of -0.1 C. Exp2: 2.48g of an unknown salt added to 160. mL of wa...

**Intermediate Algebra**

A basketball team recently scored a total of 95 points on a combination of 2-point field goals, 3-point field goals, and 1-point foul shots. Altogether, the team made 54 baskets and 16 more 2-pointers than foul shots. How many shots of each kind were made? How many 1-point fou...

**pllllls heeeeeeeeelp math**

In the image the equals sign is a typographical error

**pllllls heeeeeeeeelp math**

How do you proceed after that?

**Math**

Can you show and easy way to show this formula in the form of an equation Example: a = b × r/100

**physics**

An underwater micriphone is used to record sounds emitted by porpoises. The minimum intensity level the instrument can record is 30.9dB. Assuming a porpoise emits sound at a rate of 0.0603J/s, what is the maximum distance at which the animal will still be recorded? Neglect sou...

**physics**

An underwater micriphone is used to record sounds emitted by porpoises. The minimum intensity level the instrument can record is 30.9dB. Assuming a porpoise emits sound at a rate of 0.0603J/s, what is the maximum distance at which the animal will still be recorded? Neglect sou...

**physics**

An underwater micriphone is used to record sounds emitted by porpoises. The minimum intensity level the instrument can record is 30.9dB. Assuming a porpoise emits sound at a rate of 0.0603J/s, what is the maximum distance at which the animal will still be recorded? Neglect sou...

**physics**

An underwater micriphone is used to record sounds emitted by porpoises. The minimum intensity level the instrument can record is 30.9dB. Assuming a porpoise emits sound at a rate of 0.0603J/s, what is the maximum distance at which the animal will still be recorded? Neglect sou...

**physics**

An underwater micriphone is used to record sounds emitted by porpoises. The minimum intensity level the instrument can record is 30.9dB. Assuming a porpoise emits sound at a rate of 0.0603J/s, what is the maximum distance at which the animal will still be recorded? Neglect sou...

**physics**

An underwater micriphone is used to record sounds emitted by porpoises. The minimum intensity level the instrument can record is 30.9dB. Assuming a porpoise emits sound at a rate of 0.0603J/s, what is the maximum distance at which the animal will still be recorded? Neglect sou...

**Biology - Uncertainty (Repost)**

I'm doing a bio lab, and I have collected data on heart rate measured in beats/15 secs with an uncertainty of +/- 1 beat/sec. To get heart rate per minute, I multiplied my data by 4, making my uncertainty +/- 4 beats/min. However, what I need to do now is some subtraction,...

**Biology - Uncertainty**

I'm doing a bio lab, and I have collected data on heart rate measured in beats/15 secs with an uncertainty of +/- 1 beat/sec. To get heart rate per minute, I multiplied my data by 4, making my uncertainty +/- 4 beats/min. However, what I need to do now is some subtraction,...

**Math**

PLEASE!

**Math**

I need an example of the Associative property.

**French**

I've been given an article and some questions to answer. One of them is: "Au paragraphe deux que veulent dire les mots... a) enjeux b) nouvelle" I can't figure out what the question is asking me to do with those two words.

**French**

I want to translate this phrase into French: "When I can no longer create anything, I'll be done for." -Coco Chanel How would I translate the expression "I'll be done for"?

**Physics**

"At what point between two masses of 20kg and 15kg located 1.0m apart, will the gravitational field strength equal zero?"

**Physics**

"A workman sitting on top of a roof of a house drops his hammer. The roof is smooth and slopes at an angle of 30.0 degrees to the horizon. It is 32m long and its lowest point is 32m from the ground. How far from the house's wall is the hammer when it hits the ground?&...

**Physics - Another Question**

"Three forces act at a single point. Two of the forces are 39N southwest and 45N north. What is the value of the third force that creates equilibrium?"

**Physics**

"Two wooden blocks A and B have respective masses of 3.0kg and 4.0kg and are connected with an inextensible cord. If the blocks are placed on a horizontal frictionless surface and a force of 8.0N is applied to A, find the tension in the connecting cord."

**Physics**

"A mass of 3.08kg oscillates on the end of a horizontal spring with a period of 0.323s. What acceleration does the mass experience when its displacement is 2.85m to the right?"

**Physics**

"Determine the restoring force of a pendulum that is pulled to an angle of 12.0 degrees left of the vertical. The mass of the bob is 300.0g."

**Never mind!**

Thanks, but I figured it out.

**Physics**

"Water flows over a section of Niagara Falls at the rate of 1.2*10^6 kg/s and falls 50.0m. How much power is generated by the falling water?" It's a the kg/s that is confusing me. I don't know how to work with it.

**Physics**

"A wave travels from one medium to another, and the wavelength decreases. What happens to the velocity and the frequency?" I know that frequency will remain the same, because it is controlled only by the source. But does the velocity decrease? According to Snell'...

**Physics**

Ah! Thank you so much!

**Physics**

"Point S1 and S2 are close sources of circular water waves each of wavelength 6.0cm. P is a point some distance away from the sources. Explain whether the following path differences (path difference = PS2 - PS1) result in nodes or anti-nodes. a) 6.0cm b) 9.0cm c) 18cm d) ...

**Physics**

Thank you so much!

**Physics**

"Vibrators A and B are sources of waves with different wavelengths and they are placed close to one another in a ripple tank. Waves from source A have a wavelength of 8.0cm while those from B have a wavelength of 10cm. The waves start out in phase with each other. For eac...

**Physics - Another Question**

"A meter stick is held vertically behind an object on a spring. The object vibrates from the 20cm mark to the 32cm mark on the stick. Find the displacement when the object is at the 20cm mark, 24cm mark, 26cm mark, and 30cm mark." I had found the equilibrium position...

**Physics**

"What happens to the energy associated with a wave after the wave has been damped out?" I'm assuming all the energy is lost by then, am I right?

**Physics**

Thank you!

**Physics**

"Two springs are hooked together and one end is attached to a ceiling. Spring A has a spring constant of 25N/m, and spring B has a spring constant of 60N/m. A mass weighing 40.0N is attached to the free end of the spring system to pull it downward from the ceiling. What i...

**Never mind!**

Thanks, I got it.

**Physics**

"Two masses, 2000kg and 5000kg, are placed 20m apart. A third mass of 5000kg is placed in between the two large masses a distance of 5.0m from the larger mass. What is the force acting on the 500kg mass?"

**Physics**

"If a small planet were located 8 times as far as the Earth's distance from the Sun, what would be its period in Earth years?" (22.5 earth years) As a note, we are given a table with all of the planets' masses and radii.

**Never mind!**

Thanks, but I got it.

**Physics**

"An athlete whirls a 3.7kg shot-put in a horizontal circle with a radius of 0.90m. If the period of rotation is 0.30s, how far would the shot-put travel horizontally if it is released 1.2m above the level ground?" There were two other parts to the question that I had...

**Physics**

Oh thank you so much!

**Physics**

"A roller coaster reaches the top of the steepest hill with a speed of 1.4m/s. It then descends the hill which is at an average angle of 45 degrees and is 50m long. What will its speed be when it reaches the bottom?"

**Physics**

I figured it out, thank you!

**Physics**

"A 5000kg helicopter accelerates upwards at 0.50m/s^2 while lifting a 2000kg car. What is the lift force exerted by the air on the propellers?" I don't understand what the problem is asking for.

**Physics - Another Question**

"Two girls, one of mass 40kg and the other of mass 60kg, are standing side by side in the middle of a frozen pond. One pushes the other with a force of 360N for 0.10s. The ice is essentially frictionless. What is each girl's acceleration?"

**Physics**

Thank you for answering both questions! I understand them now.

**Physics**

"A fish hangs from a spring scale supported from the roof of an elevator. If the elevator has an upward acceleration of 1.2m/s^2 and the scale reads 200N, under what circumstances will the scale read 150N? What will the scale read if the elevator cable breaks?" There...

**Physics**

I'm learning about Newton's Laws of Motions and I'm having trouble understanding these questions: "A rear-end collision between a soft-drink truck and a car occurs. The truck driver claims the car backed into him, while the auto driver claims that the truck hi...

**Physics - Another Question**

Oh, thank you drwls!

**Never Mind!**

Sorry, I figured it out!

**Physics - Another Question**

"An airplane if flying level at 80.0m above the ground with a speed of 350km/h. The bombardier wishes to drop food and medical supplies to hit a target on the ground. At what horizontal distance from the target should the bombardier release the supplies?"

**Physics - Projectile Motion**

Ah, I see! Thank you!

**Physics - Projectile Motion**

"A person fires a bullet horizontally from a gun at the same instant that another bullet is dropped from the same height as the rifle barrel. Discuss which bullet will hit the ground first." I'm thinking that the bullet that is dropped will hit first, because it ...

**Physics**

"An airplane is climbing at an angle of 15 degrees to the horizontal with the sun directly overhead. The shadow of the airplane is observed to be moving across the ground at 200 km/h. How long does it take for the plane to increase its altitude by 1000 m"? There was ...

**Physics**

"An object is rolled up an incline. If the object is 2.75 m up the incline after 4.50s and rolling back down at a velocity of 1.90 m/s, what is the acceleration of the object?" Is this a case of final velocity - initial velocity?? It seems like an easy problem, but I...

**Physics**

Thank you! I got it!

**Physics**

"A diver springs upward with an initial speed of 1.8 m/s from a 3.0 m board. Find the velocity with which the diver strikes the water." Help please!

**Calculus**

Oh I see! Thank you!

**Calculus**

"The illumination of an object by a light source is directly proportional to the strength of the source and inversely proportional to the square of the distance from the source. Two streetlights are 40m apart and one is twice as strong as the other. Where is the darkest s...

**Algebra--One Quick Question**

I say A. This is not a geometric sequence. It's arithmetic.

**Calculus**

Thank you both!

**Calculus**

"Differentiate x^(x^3)" I can do it when the base is a number, but I'm confused as to how to do it with x as the base.

**Calculus **

Thank you both! However, the problem is I can't seem to visualize the diagram correctly. I can't see where the right triangle is coming from. But no worries, I will look at more example problems and see if I can figure these questions out.

**Calculus **

"At 9am ship A is 50 km east of ship B. Ship A is sailing north at 40km/h and ship B is sailing south at 30km/h. How fast is the distance between them changing at noon?" I can never get these type of questions where two ships are heading in different directions and o...

**Calculus**

"At 9am ship A is 50 km east of ship B. Ship A is sailing north at 40km/h and ship B is sailing south at 30km/h. How fast is the distance between them changing at noon?" I never know how to set questions like this up!

**Never Mind!**

Oops! I just found out that I don't need to know how to do this type of question.

**Calculus**

"Evaluate the following indefinite integral using integration by parts: *integral sign* tan^-1(x) dx" I let u = tan^-1(x) and dv = dx. Is that right?

**Chemistry**

"An aqueous sodium borate solution is titrated to the second endpoint with 0.225 mol/l nitric acid in the presence of a suitable indicator. If an average of 12.6mL of titrant are required to reach the second endpoint for a 25.0 mL sample, what is the base concentration?&q...

**English - Macbeth**

In Act 3, scene 3, Macbeth sends a third murderer to help the other two murder Banquo and his son. Does the third murderer know as much about Banquo as Macbeth says he does? From what I see, it seems as if it could go either way. For example, this part: "Almost a mile, bu...

**science/chemistry**

Dr Bob I dont like B or C or D that only leaves A Is this what you would go for ???? Thanks andy

**science/chemistry**

Qc for the following chemical reaction 3CIO2-(aq)<-->2CIO3-(aq)+Cl-(aq) Choices A:3[CIO2-]/2[CIO3-][Cl} B:2[CIO3-][Cl]/3[CIO2-] C:[CIO2-]^3/[CIO3-]^2[Cl-] D:[CIO3-]^2[Cl-]/[CIO2-]^3 I like B: what would you go for?? thanks all

**CHEMISTRY!!**

Thanks Dr BOB !!!!!! Andy

**CHEMISTRY!!**

Yes the text book says and I quote: V=nRT/P=(1.000mol)(8.314kPa L/mol K)(273.15 K)/100kPa=22.71L This is the molar volume of any ideal gas at STP.(if non-si units of atmospheres and the gas constant value of 0.08206 atm L/mol are used , the value is 22.41 L Hope that helps... ...

**CHEMISTRY!!**

2.27 sounds the best option It cant be 5.53 or 4.42 the maths dont add up!!! So i agree thanks

**Chemistry**

Ok, yes you're right. Thank you! No, I'm not. :)

**Chemistry**

I am designing a procedure for a lab where I have to use indicators to create an acid-base table from 6 solutions. I am just wondering...if I put a drop of indicator into a solution, do I have to dispose of it and obtain new solution before putting in another type of indicator...

**Chemistry**

Also, if products are favoured, does that mean that the resulting solution is basic? And if reactants are favoured, the solution is acidic? Or is there no distinction?

**Chemistry**

I am predicting acid-base equilibria using the Brondsted-Lowry predictions. I am asked to do "solid aluminum sulfate added to water". So I know there is an Al^2+ ion and a SO4^-2 ion, but does water dissociate into H30^+ and OH^-? If so, then H30^+ and OH^- would be ...

**Math - another question**

According to the binomial theorem, the term with x^2 would be the third term. I plugged my known values into the "formula" for the third term, and made it equal to 5. Then I solved for a. Sorry, my explanation is kind of vague.

**Never Mind!**

I got it. :)

**Math - another question**

"In the expansion of (2-ax)^5 the coefficient of x^2 is 5. Find the value of a". I know I have to use the binomial theorem to help me, but I don't know how.

**Math**

"Three of the coordinates of the parallelogram STUV are S(-2,-2), T(7,7) and U(5,15). State the vector ST and hence determine the coordinates of V." So I've figured out that ST = (9,9), but I don't see how that helps me find V.

**Math**

"The probability of getting heads on a biased coin is 1/3. Sammy tosses the coin 3 times. Find the probability of getting two heads and one tail". I thought that all you have to do is: (1/3)(1/3)(2/3) It makes sense to me, but it's not right...

**Math**

Oh yeah! Thank you!

**Math**

"In vase A, there are 3 red balls and 5 white balls. In vase B, there are 6 red balls and 4 white balls. Two balls are to be drawn at random, without replacement, from each vase. What is the probability of selecting 4 red balls?" (Answer: 1/28) So I thought about doi...

**Chemistry**

Sorry. "Calculate the pH for 0.10 mol/L aqueous solution of NaCl".

**Chemistry**

"Calculate the pH of NaCl". I know that NaCl is neutral...but I don't know how to show that it is neutral. The ka value for the Cl ion is "very large", so what do I do?

**Chemistry**

DrBob, if you're still on...what do I do for NaCl??

**Chemistry**

Oh you're right! Thanks.

**Chemistry**

Ohhh! Ok! Thank you for that! I missed a class, and so I'm relying on my notes to teach me...which isn't easy. Interesting little fact btw.

**Chemistry**

Is the initial concentration for Al(H20)6 also 0.10 mol/L?

**Chemistry**

No, it doesn't. But I have it in my notes. Ok, I think I understand how to approach this. Thanks!

**Chemistry**

Sorry, I have a question within a question. I think the ka value for the aluminum ion is used for when we have a solution like AlCl3, right? When you dissociate it, the Cl ion has a very large ka value...so we use the ka for Al instead? I hope I'm making sense. :)

**Chemistry**

Oops! Sorry, I figured it out. But I still need help...I'm not clear on the process.

**Chemistry**

"Calculate the pH of 0.10 mol/L aqueous solution of aluminum sulfate." I am also given the ka value for the aluminum ion (9.8x10^-6)...but I don't know why I need it. I'm not even sure if I need to use it. Help please?

**calculus**

The manager of a large apartment complex knows from experience that 100 units will be occupied if the rent is 350 dollars per month. A market survey suggests that, on the average, one additional unit will remain vacant for each 7 dollar increase in rent. Similarly, one additio...

**Calculus**

Sorry! I got it. I forgot that revolving around a line can change which function is outer and which is inner.

**Calculus**

"Find the volume of the solid generated by revolving the region bounded by the graphs of the given equations about the indicated lines: y = 2x^2 y = 0 x = 2 About the line y = 8"

**Calculus**

"Evaluate the following indefinite integrals: "S" (3x^2 -2)/(x^3 - 2x + 1)^3 dx" We're practicing the substitution rule, and I know how to do it, but I don't know what/how to substitute in this question. btw: "S" is the integral sign.

**Chemistry**

Hm...if I use (2 mol)(743 kJ/mol), I end up with a positive delta H, which doesn't make sense (combustion -> exothermic).

**Chemistry**

Really? I'm pretty sure part of the process lead to the value -330 kJ/mol... We're looking for 1 mole of carbon monoxide...is the value we've calculated for 2 moles?