Posts by Anon
Total # Posts: 3,231

chemistry
If you have 500 ml of .15M Formic Acid, what is the pH of this solution? What is the pKa? How many grams of Sodium Formate would you have to add to raise the pH to 3.85? How many grams of HCl would you have to add to lower the new pH by .2 ? 
history
What policies led to the Boxer Rebellion? 
physics
A helicopter is hovering above a road at an altitude of 24 m. At a certain time, the distance between the helicopter and a car on the road is 45.0 m. Calculate the angle of elevation of the helicopter from the car. (32.2o ) 
Climate Change
Water is a greater absorber of IR than CO2, it also makes up 4% of the air by volume. If 0.016% change in CO2 over 100 years can increase the temperature by 1 deg C, what is the effect of the 4% water vapour on the temperature? Also do you think that answer makes sense? 
physics
Orson rides his power boat up and down a canal. The water in the canal flows at 10 km/hr. Orson takes 5 hours longer to travel 360 km against the current than he does to travel 360 km with the current. What is the speed of Orson's boat in still water? (39.2 km/hr) 
physics
The height of a ball thrown up with a velocity of 39.2 m/s is given as a function of time(measured in seconds) by the equation H(t) = 39.2t 4.9t2 + 58.8. How much time will the ball take to fall to the ground? (9.29 s) pls explain how to solve the answer  ^ if you're doing misson acad. it is infact wrong

algebra
Check my answer? What is the order of the numbers from least to greatest? A= 6.2x10^5, B= 1.1x10^3, C= 4.3x10^3, D= 5.2x10^5 I think it's D,B,C,A (5.2x10^5, 1.1x10^3, 4.3x10^3, 6.2x10^5) 
Trigonometry
What is the value of tan (Arc cos 15 seventeenths)? 1. 8/15 2. 8/17 3. 15/8 4. 17/8 Can you guys explain what the Arc means? 
english
Which of the following text examples supports the conclusion that Father will never stop building things? Choose all that apply. A) he builds Dragonwings despite the financial hardship it causes. B) after setting a kite free, he offers to build separate kites for Miss Whitlaw... 
Charges
Three point charges are placed along a straight line with successive charges being 3.0 m apart. The central one has a charge of ?3.0 ?C, whilst the outer two have charges of +3.0 ?C each. If the charges are separated by a vacuum, calculate the magnitude of the total force on ... 
Science
Can I use a=qE/m to work this out? Since f=ma and f=qE 
Electron acceleration
An electron has an acceleration of magnitude 2.0 × 10^13 m s?2 in a uniform electric field. What is the magnitude of the electric field? Can I use f=ma? 
Orbital period
A planet orbiting a certain star is observed to have an orbital period of 65 days with an orbit whose semimajor axis is 3.8 × 107 km. A second planet orbiting the same star has an orbital period of 450 d. What is the semimajor axis of its orbit?  So 200km/h is 55.5 m/s and 50km/h is 13.75 m/s. Wi=55.5/0.4=138.75 Wf=13.75/0.4=34.36 (138.7534.36)/3= 34.7 Thanks bob. I think this is correct, forgive my lack of units.

Angular acceleration
A racing car accelerates from 50 km per hour to 200 km per hour in 3.0 seconds along a straight track, and the acceleration is constant during this period. If the axles are 40 cm above the road, what is the magnitude of the angular acceleration of the wheels? 
Chemistry
The radioisotope radon222 has a halflife of 3.8 days. How much of a 65g sample of radon222 would be left after approximately 15 days?  thank you!

math
suppose u = (1, 2, 3, 4, 5, 6, 7, 8) is the universal set and p = (1, 2, 3, 4). what is p? a.) (5, 6, 7, 8)*** b.) (1, 2, 3, 4, 5, 6, 7, 8) c.) (1, 2, 3, 4) d.) cannot be determined i think it's a.) (5, 6, 7, 8) am i right? 
Math
While attending a film festival you decide that there are 12 movies that you are interested in seeing. However, you only have time to see 7 movies. In how many different ways can you watch 8 of the 12 movies? A. 19,958,400 B. 12 C. 9,979,200*** D. 1,663,200 
Physics
A car is speeding along the motorway at 40 m s when the driver observes an accident ahead. He slams on the brakes, the wheels lock immediately, and the car skids to a halt. You may assume that the car travels in a straight line whilst it is skidding and that the magnitude of ... 
math
The ___ of a function consists of the set of all output values. 
Physics
A cricket jumps vertically upwards, and remains in the air for 1.6 s. At what speed did it leave the ground?  oh so its d?

math
1. What are the minimum, first quartile, median, third quartile, and maximum of the data set? 18, 20, 11, 10, 8, 6, 12, 4 A: Minimum: 4; First Quartile: 7; Median: 10.5; Third Quartile: 17.5; Maximum: 20 B: Minimum: 4; First Quartile: 5.5; Median: 12.75; Third Quartile: 15; ...  Im just doing corrections so i can understand how to properly do it Reiny

Algebra
Patty’s Burgers sells three hamburgers and two milkshakes for three dollars and thirty five cents. One hamburger and one milkshake cost one dollar and thirty cents. Find the cost of a hamburger. I got 89 cents but its not working 
Physics
Copper has a Fermi energy of 7.02 eV. What is its electron number density?  Using Ef=h^2/8m(3n/pi)^2/3 I get an answer of 2.246*10^7 but this is incorrect. I know the answer is 1.8*10^29 but am struggling to see where I went wrong. Can anyone help? 
Physics
A swimmer launches himself upwards from a springboard 5.0 m above the surface of the water in a swimming pool. His trajectory is (almost) vertical, and from the top of his trajectory he passes the springboard in just half of the time he takes to reach the water. How high above... 
Physics
If enough energy were supplied to a diamond would that allow some of its electrons to transition to a higher energy band and therefore conduct electricity? Just curious. 
Physics
A man stands on the edge of a cliff with hands outstretched horizontally carrying two stones, one in each hand. At time t= 0, he drops the first pebble from rest. After a time of 1.0 s, he releases the second pebble. At what time will the separation between the pebbles be 66 m? 
Physics
A man stands on the edge of a cliff with hands outstretched horizontally carrying identical pebbles, one in each hand. At time t= 0, he drops the first pebble from rest.When this pebble has fallen by 2.0 m, he releases the second pebble. What is the vertical distance between ...  Great steve thank you! knew it was simple.

Physics
A rocket travels vertically away from the surface of Mars. It is still close to the surface and travelling at a speed of 25 m s when it jettisons an empty fuel tank. The fuel tank initially travels with the velocity of the rocket, but it is attracted to Mars and reaches the ...  Thank you!

Chemistry
CH3OH(aq) + OH(aq) ? CH3O(aq) + H2O(l) If methanol has pKa = 18.3, what is pKb for its conjugate base?  Answer C Ms. Sue

English
Read these lines from T.S. Elliot's "Preludes." "Six o’clock./The burntout ends of smoky days./And now a gusty shower wraps/The grimy scraps/Of withered leaves about your feet/And newspapers from vacant lots..." Which of the following is being ... 
Physics
So a quick question. If im representing a quantum gas with diagrams of the allowed configurations of the gas. When it comes to indistinguishable I have 7 configurations. But if we then compare to a gas made up of distinguishable particles. Would there be more or less ...  Thank you Ms. Sue :)

Algebra 1
Measures of Central Tendency and Dispersion Practice 2. Tell which measure of central tendency best describes the data. Time spent on Internet (min/day) 75 38 43 120 65 48 52 A. Mean B. Median C. Mode Help? I really don't understand this :/ 
English
Choose the word or phrase that best defines the italicized word. "An aged man is but a *paltry* thing,/ A tattered coat upon a stick..." a.inadequate b.invisible c.significant d.unwise 
English
Choose the word or phrase that best defines the italicized word. "An aged man is but a *paltry* thing,/ A tattered coat upon a stick..." a.inadequate b.invisible c.significant d.unwise 
Chemistry, Periodic Table
Very brie?y explain the main horizontal and vertical features of the Periodic Table in terms of the electronic structure and relevant quantum numbers?  Am I being asked to state for instance in the case of Halogens that as we progress down the column the quantum ... 
Physics
How would electrical current be affected if the time interval over which a charge passes through an area increases while the amount of charge Remains the Same 
Chemistry
A little confused on this question... I think I would need to take the solute and put it over the solvent, and then use molar mass. Confused on how density plays into this problem. Sucrose is very soluble in water. At 25ºC, 211.4 grams of sucrose will dissolve in 100 g of...  So, for this problem would I need to take the square root of all of the Ksp values in order to find the greatest solubility?

Chemistry
Which of the following compounds has the greatest molar solubility? A) AgBr, Ksp= 5.4 x 10^13 B) Ba3(PO4)2, Ksp = 3.0 x 10^23 C) Al(OH)3, Ksp = 1.9 x 10^33 D) MgF2, Ksp = 7.4 x 10^11 E) Pb(OH)2, Ksp = 1.2 x 10^15 I know the answer for this problem is D. Would it be safe to... 
Chemistry
What is the boiling point elevation of a solution of NaNO3 (85.0 g/mol, complete dissociation) made by dissolving 10.0 g of NaNO3 into 200 g of water (Kb = 0.512?C/m)? 
Physics
Getting my head twisted around by the wording of these two questions, any help would be appreciated. My answers/ideas are below each question. 1) Brie?y explain whether there would there be more or fewer con?gurations available for the gas if the particles were distinguishable...  Hi Bob, Thanks for answering, I have gone the long way around with this question as im still not sure how I can end up with the average number of particles in N_3 can be 8/7. But according to my textbooks the answer should be arrived at as follows: <N_3>= (0*1/7)+(2*1/7...

Physics
So I have worked out the 'allowed' configurations for four particles which can occupy 5 different energy levels (1, 3, 5, 7, 9) and now I need to work out the average number of particles in a particular energy level (i.e 3). 1) 9,5,1,1 2) 9,3,3,1 3) 7,7,1,1 4) 7,3,3,3 ... 
Bose gases, quantum physics.
A hypothetical gas consists of four indistinguishable particles. Each particle may sit in one of ?ve allowed quantum states, with energies ?,3?,5?,7? and 9?. Assume that the total energy of the gas is ?xed at 16?. (a) If the particles are bosons: . (i) What is the probability ... 
maths
Sketch the region bounded by the xaxis, the curve y = x2 + x + 1 and the lines x = 2 and x = 5. Write down a de?nite integral that represents the area of that region Just stuck getting points for the first equation as when I put y=0 I got a complex root? 
Calculus AP
f is a differentiable function on the interval [0, 1] and g(x) = f(2x). The table below gives values of f ?(x). What is the value of g ?(0.1)? x 0.1 0.2 0.3 0.4 0.5 f ?(x) 1 2 3 –4 5 The answers are: 1 2 4 cannot be determined I got 1 please let me know if this is right ...  Thank you!

Biology
Describe the microbial loop and role of viruses simplified. I just dont understand it if anyone could please help or suggest a website? 
Physics
A concave mirror with a radius of curvature of 1.7 m is illuminated by a candle located on the symmetry axis 3.7 m from the mirror. Where is the image of the candle? Answer in units of m 
Physics
A concave mirror has a radius of curvature of 1.61 m. Calculate the position of the image produced when an object is placed 2.66 m from the mirror. Answer in units of m. Calculate the position of the image when an object is placed 0.492 m from the mirror. Answer in units of m. 
Physics
Of the following materials, sound waves travel fastest through...? Helium at room temperature Air at room temperature Water at room temperature Steel at room temperature 
Physics
Outline how the Bohr Theory for the hydrogen atom (as represented by the formula in part (b) above) can be modified to explain the characteristic Xray line spectra emitted by metals. Calculate the wavelength of the K? line from platinum where Z = 78  You did not get the last one correct. The last one would be the 3rd one because if you simplify it it would equal 6^7 just simplify every one and you can figure out what it equals. So like the second one would be d and the the first would be B.

Pysics
Calculate the focal length of a concave spherical mirror that projects an image 12.0 cm in front of the mirror with a magnitude of 0.42 
Algebra 1
9. Find the solutions to the system. y=x^2+5x+6 y=4x+12 A. (2,20) and (3,0) B. (2,20) and (3,18) C. (2,20) and (3,18) D. no solutions 10. Find the solutions to the system. y=x^23x1 y=8x1 A. (0,1) and (11,388) B. (0,1) and (11,87) C. (1,0) and (87,11) D. no ... 
Quantum Physics
A particle of mass 2.00×10^?10 kg is con?ned in a hollow cubical threedimensional box, each edge of which has a length, 2.00×10^?10 m, and for which the potential energy function is zero inside, and in?nite outside, the box. The total energy of the particle is 2.... 
Physics
(a) Photoelectrons with a maximum kinetic energy of 7.6eV are emitted from a metal when it is illuminated by ultraviolet radiation with a wavelength of 1.3×10^2 nm. (i) What is the energy of the incident photons in electronvolts? (ii) What is the wavelength of the ...  can you please show me how to do this equation im not really good with reading math but anything helps!

Algerbra 1 B
Simplify the radical expression. Show all your steps. \sqrt{363} 3 \sqrt{27}  could it be C?

Math
PLEASE HELP PLEASE Does the series diverge or converge? How do you know? 3+6+12+24+... 
MathAlgebra II to be exact
Come up with a new linear function that has a slope that falls in the range ?1< m <0 . Choose two different initial values. For this new linear function, what happens to the function’s values after many iterations? Are the function’s values getting close to a ... 
Chemistry
A solution contains 1.4?*?10^?5 mol of KBr and 0.14 mol of KCl per liter. AgNO3 is gradually added to this solution. Which forms first, solid AgBr or solid AgCl? Or do they coprecipitate? 
Social Studies
McCarthyism was able to become strong because of the increasing fear of Communism in China and Eastern Europe that came to the United States. True** False The term "McCarthyism" comes from Senator Jake McCarthy, who spearheaded the drive to defeat Democratic ...  D C Essay D C B D A B Essay

Math
Write an equation for a rational function whose graph has all of the indicated features. x  intercept of 4 y  intercept of 2 vertical asymptote with equation x = 2 horizontal asymptote with equation y = 1 
Physics
Optics/Lens problem. Is the image real or virtual? A converging lens of focal length f1 = +22 .5cm is placed at a distance d = 60 .0cmtotheleft of a diverging lens of focal length f2 = ?30.0cm. An object is placed on the common optical axis of the two lenses with its base 45.... 
Physics
an 11.5 kg object with a temperature of 25.0 degrees celsius is attached to a pulley mechanism. it is allowed to fall until is slows to rest after falling 1.6 m. at the end of the fall , the object has a temperature of 28.9 degrees celsius. what is the specific heat of the ...  i) the change in entropy is zero as its isothermal. ii) Also zero. iii) use P deltaV=q.
 Anyone got any ideas? I think I can find the work done but im not sure about the other questions.

Physics
A sample of 8.02×10^?1 moles of nitrogen gas (? =1 .40) occupies a volume of 2.00×10^?2 m^3 at a pressure of 1.00×10^5 Pa and temperature of 300K. The sample is isothermally compressed to exactly half its original volume. Nitrogen behaves as an ideal gas ...  So if I know the average kinetic energy of one mole of helium atoms. Can I just times this by five to obtain the answer to ii) ? this seems deceptively simple.

Physics
A sealed container of volume V =0 .10m^3 holds a sample of N =3 .0×10^24 atoms of helium gas in equilibrium. The distribution of speeds of the helium atoms shows a peak at 1.1×10^3 ms^?1. (i) Calculate the temperature and pressure of the helium gas. (ii) What is ...  it's b

math
The square root of 76 is between what two numbers? 
math
The square root of 76 is between what two numbers?  Anyone else like the new 50 v 50 fortnite game mode? Lol

Optics
A converging lens of focal length f1 = +22 .5cm is placed at a distance d = 60 .0cm to the left of a diverging lens of focal length f2 = ?30.0cm. An object is placed on the common optical axis of the two lenses with its base 45.0cm to the left of the converging lens. (a) ... 
Physics
A 6.50 horsepower self propelled lawn mower is able to travel at 0.56 m/s, starting from rest, in 0.050 s. If the lawn mower has a mass of 48.0 kg, what distance does the lawnmower travel in that time? (1 hp = 746 W) 
Chemistry
One liter of a buffer composed of 1.2 M HNO2 and 0.8 M NaNO2 is mixed with 400 mL of 0.5 M NaOH. What is the new pH? Assume the pKa of HNO2 is 3.4. 
Induced current, EMF.
What is the maximum magnitude of the induced current in mA and how many times does this occur per second?  For the second part of this question since I know the Angular Velocity (w) of a rotating coil with experiences this current can I use f=w/... 
Chemistry
write unbalanced oxidation and reduction reactions for the following processes: Mn³?(aq) ? MnO?(s) + Mn²?(aq)  Okay I changed C) and used one less term and got 0.31028 as the answer. What does that mean?

Math (Calculus)
The prompt for this question is f(x) =sin(x^2) A)Write the first four terms of the Maclaurin series for f(x) B)Use the Maclaurin series found in Part A to approximate the integral from 0 to 1 of sin(x^2) dx C)How many terms are needed to find the value of the integral given in... 
Math (Calculus)
How can I sketch a graph of the first two partial sums for the following power series: Sum(n=1 to infinity) ((2x+5)^n) / (n(4^n)) 
Math (Calculus)
Consider the curve represented by the parametric equations x(t)= 2+sin(t) and y(t)=1cos(t) when answering the following questions. A) Find Dy/Dx in terms of t I got tan(t) B) Find all values of t where the curve has a horizontal tangent. I got (+)(pi)(n) C) Find all values ...  I actually do not know how to do the rest, I am completely lost on this. For part A, when writing the first terms, are they just: x^2 x^6/3! + x^10/5!  x^14/7! or do I have to plug in numbers 1 through 4, and then solve to get the first four terms?

Math
The prompt for this question is f(x) =sin(x^2) A)Write the first four terms of the Maclaurin series for f(x) B)Use the Maclaurin series found in Part A to approximate the integral from 0 to 1 of sin(x^2) dx C)How many terms are needed to find the value of the integral given in...  So the answer to B is t=+ (pi)(n) and for C it is (pi/2)(+)(pi)(n)

Math
Consider the curve represented by the parametric equations x(t)= 2+sin(t) and y(t)=1cos(t) when answering the following questions. A) Find Dy/Dx in terms of t B) Find all values of t where the curve has a horizontal tangent. C) Find all values of t where the curve has a ... 
Math
50 = 1/2 ? (4.88)² dr/dt Can someone solve this?