Posts by hannah
Total # Posts: 3,512

Physics(thank you for the help)
A hotair balloon is rising upward with a constant speed of 2.45 m/s. When the balloon is 3.22 m above the ground, the balloonist accidentally drops a compass over the side of the balloon. How much time elapses before the compass hits the ground? I know that average speed ... 
Physics(Please respond)
1) A cave explorer drops a stone from rest into a hole. The speed of sound is 343 m/s in air, and the sound of the stone striking the bottom is heard 1.33 s after the stone is dropped. How deep is the hole? I did 343 / 1.33. Is this correct? Physics(Please help)  drwls, ... 
Physics(thank you for the help)
I do not know how to solve for a ratio. 
Physics(thank you for the help)
1) A baby elephant is stuck in a mud hole. To help pull it out, game keepers use a rope to apply a force FA. By itself, however, force FA is insufficient. Therefore, two additional forces FB and FC are applied. Each of these additional forces has the same magnitude F. The ... 
Physcis(Please help)
A pilot flies her route in two straightline segments. The displacement vector A for the first segment has a magnitude of 254 km and a direction 30.0o north of east. The displacement vector for the second segment has a magnitude of 178 km and a direction due west. The ... 
Physics
1) A jetliner, traveling northward, is landing with a speed of 69.3 m/s. Once the jet touches down, it has 787 m of runway in which to reduce its speed to 13.6 m/s. Compute the average acceleration (magnitude and direction) of the plane during landing (take the direction of ... 
Physics(Please help)
When I put 21.792 m/s as my answer my online homework said it was incorrect. Why?? 
Physics(Please help)
Determine the final speed assuming that the time elapsed since t=0 is 2.4s. Initial velocity is +12m/s acceleration is +3.4m/s^2 I tryed doing 12/2.4 and then 12/3.4 but both of these were incorrect? I am not sure what to do. Thank you. 
Physics(Please help)
For some reason when i put in 5.4 as the answer it said I was incorrect. I do not know why. 
Physics(Please help)
1) The velocity of a diver just before hitting the water is 11.8 m/s, where the minus sign indicates that her motion is directly downward. What is her displacement during the last 1.06 s of the dive? I know that the formula for displacement is deltaX= x  x0. Would I do 11.8... 
Physics(Please help)
So I would set my problem up as (13.3  X/343)^2 = x/1.76 The only thig I am not sure of is how to solve for the x. 
Physics(Please help)
1) A cave explorer drops a stone from rest into a hole. The speed of sound is 343 m/s in air, and the sound of the stone striking the bottom is heard 1.33 s after the stone is dropped. How deep is the hole? I did 343 / 1.33. Is this correct? 
Physics(Please respond)
1) A penny is dropped from rest from the top of a very tall building. Assuming the height of the building is 407 m and ignoring air resistance, find the speed with which the penny strikes the ground. I am not sure how to start this. Thank you! 
Physics(Please help)
How do you know when to use tan instead of cos or sin? 
Physics(Please help)
1) two hotair balloons are 48.2 m and 61.0 m above the ground. A person in the left balloon observes that the right balloon is 13.3° above the horizontal. What is the horizontal distance x between the two balloons? The left balloon is 48.2m and the right balloon is 61.0m... 
Physics
1)A force vector points at an angle of 12.4 ° above the +x axis. It has a y component of +337 newtons (N). Find the magnitude and the x component of the force vector. For the x component I did 337cos(12.4)=329.13 N For magnitude I am not sure what to do. 
Physics(Please help)
1) A force vector has a magnitude of 579 newtons and points at an angle 43o of below the positive x axis. Find the x scalar component and the y scalar component of the vector? For the x component I did 579cos(43) = 423.45 N. Is this correct? For the y component I did 579sin(43... 
Physics(Please help)
A football is kicked with a speed of 18 m/s at an angle of 65° to the horizontal. How long is the football in the air? Neglect air resistance Would I use the equation y=y0 + voy t 1/2gt^2 ? 
Physics(Please respond)
1) Which components remain constant throughout the motion? vx = x component of the velocity vy = y component of the velocity ax = x component of the acceleration ay = y component of the acceleration I know that ax and ay remain constant but I am not sure about vx and vy. Thank... 
Physics(Please respond)
There is a diagram of a ball being thrown in a horizontal diection at 30m/s and there is an angle of 48degrees and a side with 4m. How long is the ball in the air? I am confused because I am not sure of the equation. I know that is is something like y = yo + ?  1/2gt^2 Thank... 
statistics (college
An insurance company checks police records (in a city) on 500 accidents selected at random and notes that teenagers were at the wheel in 120 of them. It is desired to test if this information indicate that more than 20% of auto accidents involve teenage drivers in the city. ... 
Calculus
Integrate e^((x^3)/2) How do I start? I know that the integral of e^x is just e^x plus C, but what do I do with the ((x^3)/2)? Thanks! 
pre calculs
Is that supposed to be f(x)=3x^27x2? 
Physics
1) Which components remain constant throughout the motion? vx = x component of the velocity vy = y component of the velocity ax = x component of the acceleration ay = y component of the acceleration I know that ax and ay remain constant but I am not sure about vx and vy. 
Mathematics I
Evaluate definite integral from 2 to 0. Integral((x^2)(e^((x^3)/2)dx) Do those parentheses make sense? The power of e is x^3 divided by two. Can someone give me the first step, and I'll see if I can get it from there. I don't want to make you just do the problem for ... 
physical sciences
Carbon has an atomic number of 6, which means it contains 6 electrons. To find the number of neutrons, just subtract the atomic number from the mass number. So 146 = 8. There are 8 neutrons in an atom of carbon with a mass number of 14. 
Chemistry
Why do chloride ions increase corrosion? 
Physics
Thank you!! 
Physics
Vector A has magnitude of 9.77 units and points due east. Vector B points due north. 1) What is magnitude of B, if the vector A+B points 34.7 north of east? 2) Find magnitude of A+B I am not sure what formulas to use for this. If someone could show me how to start this I will ... 
Physics(Please check)
Which equations are dimensionally correct? F=ma E=max X=(1/2)at^3 V=sqrt(2*fx/m) E=(1/2)mv I think that F=ma , E=(1/2)at^3, V=sqrt(2*fx/m) are correct. Would you agree? 
Physics(Please help)
thank you! 
Physics(Please help)
A force, F1 of magnitude 2.0N and directed due east is exerted on an object is F2=2.0N due north. What is the magnitude and direction of a third force, F3, which must be exerted on the object so that the resultant force is zero? I am not sure how to start this problem!! Thank ... 
Math
The circumference of the front tire is 6ft. How many complete turns does the front wheel make in 30 ft driveway? 
math
Compute: The number of combinations of 8 elements taken 3 at a time. The number of permutations of 8 elements taken 3 at at time. 
Physics(Please check)
I know the highest point would be 29.4 but I do not know how to get this. 
Physics(Please check)
Ok but where did the 9 come from? 
Physics(Please check)
1) How long does it take the ball to reach its highest point? I am not sure what I would divide 24 by to find this. 2) How high above the starting point is the highest point? I am not sure how to find this. 
Physics(Please check)
A 5kg ball is thrown straight up in the air with an initial speed of 24m/s. After its release and before it hits the ground when is the ball in free fall? My answer is at all times. Is this correct? Thank you. 
Physics(Please check thanks)
Thank you! 
Physics(Please check thanks)
Two vectors have magnitudes 4m and 3m. Which choice is not a possible magnitude for their resultant? 3m, 1m, 7m, 12m I chose 12m. Is this correct? 
Physics(Please respond)
why is sin negative? 
Physics(Please respond)
Vector A has a magnitude 2.4m and direction 130 degrees relative to the positive xaxis. Vector B has magnitude 3.0m and direction 250 degrees relative to the positive xaxis. 1) The resultant R=A+B has magnitude(in m) ? I know the R =2.75m but I am not sure how to get this. I... 
math
ok thank you! 
math
4 and 505/1000. but how does that help with this? 
math
calculate 10^1.27 how do i do this? 
Math
One bag contains 5 red marbles, 4 blue marbles, and 3 yellow marbles, and a second bag contains 4 red marbles, 6 blue marbles, and 5 yellow marbles. If Lydia randomly draws one marble from each bag, what is the probability that they are both not yellow? 
Chemistry
A patient with untreated diabetes may have a blood concentration of acetone of 20mg/100mL. Determine the molar mass of acetone and use this number to convert this concentration to mol/L. Okay, so I was able to determine the molar mass of acetone (= 58.09g/mol) however, i'm... 
physics
is increasing the current a valid method to increase the induced voltage when a magnet moves into a solenoid? 
Chemistry(Please help)
0.0885  x = 4.2e7 Then I added 0.0885 to the right side and got 8.85e2. Would this be the concentration or do I need to do another step? 
Chemistry(Please help)
Calculate the concentration of HCO3 in an aqueous solution of 0.0885 M carbonic acid, H2CO3 (aq). I was going to set this up as 0.0885 x = ? Am I suppose to use the Ka value for carbonic acid? 
Chemistry(Please respond)
I multiplied 0.119 by 1.58e10 and then took the square root, is that correct? 
Chemistry(Please respond)
I did 1.0e14 / 6.3e5 = 1.58e10 Then would I do (1.58e10)(0.119)? 
Chemistry(Please respond)
A 23.9 mL sample of 0.283 M trimethylamine, (CH3)3N, is titrated with 0.207 M hydrochloric acid. At the equivalence point, the pH is? I started off by doing 0.283 X 2.39e2 = 6.76e3 Then I did 6.76e3 / 0.207 = 3.36e2 2.39e2 + 3.36e2 = 5.65e2 6.76e3/5.65e2 = 0.119 I do ... 
surface area and volume
number 2 is wrong its b. 707 yd^2. 
Chemistry(Please help)
What is the molar solubility of barium phosphate in a 0.282M barium acetate solution? If I set up and ice table I would have 0.282M  X = ? Would I use the molar mass of barium acetate to complete the equation to find X? Ba3(PO4)2 ==> 3Ba^2+ + 2PO4^3 Ba(C2H3O2)2 ==> Ba^... 
Chemistry(Please help)
delta Go = 431.16kJ/mol  (298k X 0.12529 kJ/K*mol) I am having trouble converting the units for delta H and delta s to match. I multiplied delta H by 1000 to get kJ but this didn't give me the correct answer. Chemistry(Please help)  Dev, Wednesday, April 25, 2012 at 6:... 
Chemistry(Please check)
What is the molar solubility of barium phosphate in a 0.282M barium acetate solution? If I set up and ice table I would have 0.282M  X = ? Would I use the molar mass of barium acetate to complete the equation to find X? 
math
HELP PLEASE! I don't understand how to do the problem! Please help thanks(: The problem is: your bike tire has a radius of 14 inches. If your tire makes 100 revolutions, how many feet does your bike travel? THANKS! :D 
Chemistry(Please help)
I did 431.16kJ/mol X 1000 = 431160 Then 431160  (298 X 0.12529 kJ/K*mol) = 431197.33 for delta G but this answer was said to be incorrect, I do not know why?? 
Chemistry(Please help)
delta Go = 431.16kJ/mol  (298k X 0.12529 kJ/K*mol) I am having trouble converting the units for delta H and delta s to match. I multiplied delta H by 1000 to get kJ but this didn't give me the correct answer. 
Chemistry(Please help)
Now I do delta G = RT lnK So 17200 = 8.314(500) lnk 17200 = 4157 ln k This is where I am not sure what to do next do I add 4157 to the left side and then take the ln? 
Chemistry(Please help)
1) Nitrosyl chloride (NOCl) decomposes at high temperature. The equation is 2 NOCl (g) > 2 NO (g) + Cl2 (g) at 227oC Using delta Ho = 81.2 kJ and delta So = 128 J/K, calculate the value of the equilibrium constant for this reaction. I do not know how to start this problem... 
Chemistry(Please help)
So for delta G= delta H  T delta S it would be delta G= 81200 J/K  500K(128J/k) This would equal 17200. Did I do this correctly so far before I move on? 
Chemistry(Please help)
1) Nitrosyl chloride (NOCl) decomposes at high temperature. The equation is 2 NOCl (g) > 2 NO (g) + Cl2 (g) at 227oC Using delta Ho = 81.2 kJ and delta So = 128 J/K, calculate the value of the equilibrium constant for this reaction. I do not know how to start this problem ... 
Chemistry
I need to calculate the value of Kp at 25 degrees celsius using the delta Go value. Delta Go = 29.10kJ I know that Delta Go = RT lnK and that R=8.314e3kJ/K mol delta Go / RT I did 29.10 / 8.314e3 X 298K and 11.74 but this was wrong. I am stuck. What did I do wrong? 
Chemistry(Please check answers)
1) The standard molar entropy value of N2 (g) is 191.5 J/Kmol, of O2 (g) is 205.0 J/Kmol and of NO2 (g) is 240.0 J/Kmol. From these values we can calculate the Delta So for the reaction N2 (g) + 2 O2 (g)> 2 NO2 (g) to be? I did products  reactants (240 X 2)  [191.5... 
Chemistry(Please check answers)
For question 2 my actually chose that delta H is negative and delta s is positive I just typed the wrong answer in. Is this correct? 
Chemistry(Please check answers)
1) For a reaction delta Go is more negative than delta Ho. What does this mean? a. delta So is zero. b. delta So is negative c. delta So is positive d. delta So is negative if delta Ho is positive. e. delta So is negative if delta Ho is negative. I think that delta S is ... 
Chemistry
Thank you. 
Chemistry
Ok thank you the way you have it is exactly the way that it was stated on my homework. The only problem is that I realized that I had the typed the wrong number. It was suppose to be the same equation but with 2.49e1 instead 3.20e1. I understand everything except how did you... 
Chemistry
.50  x / x = 3.20e1 I need to solve for x. I was going to do .50 X 3.20e1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help. Math(Please help)  Reiny, Tuesday, April 17, 2012 at 3:18pm You probably meant (.50  x)/x... 
Chemistry(Please check)
Thank you! 
Chemistry(Please check)
I think that 2NH3(g) > N2(g) + 3H2(g) is actually the other answer that is increasing because the number of moles increases from 2 to 4. So I chose answers 1 and 3. Is this correct? 
Chemistry(Please check)
Which of the following four processes are accompanied by an increase in entropy? 1. I2 (s) > I2 (g) 2. 2 I (g) > I2 (g) 3. 2 NH3 (g) > N2 (g) + 3 H2 (g) 4. Pb2+ (aq) + 2 OH – (aq) > Pb(OH)2 (s) Answers: a. 1 & 2 b. 1 & 3 c. 3 & 4 d. 2 & 4 e. only 3 I am ... 
Chemistry(Please check)
Now that I looked over this question again I agree with that too. Thank you! 
Chemistry(Please check)
Delta G^o for a reaction can be calculated from? 1. delta G^o f data 2. Delta H^o f and delta S data 3. equilibrium constants I chose that delta G can be calculated from H and S values. Would you agree? 
Chemistry(Please check)
1) Free energies of formation are a. always positive b. always negative c. never zero d. measured at 298K e. more than one response above is correct I think that free energies can be negative or postive so the answer cannot be e. I chose answer d, they are measured at 298K. ... 
Chemistry(Please check, thanks)
ok, the next question is which choice would have the next highest standard molar entropy. This would be liquid but since there are two liquids do I compare the molar masses? 
Chemistry(Please check, thanks)
I sorry I meant that CCl4(g) would be the highest since its a gas. 
Chemistry(Please check, thanks)
Which choice below has the highest standard molar entropy? SiCl4(s), CCl4(g), CCl4(l), Si(Cl4(l) I know that the gas state has the largest entropy so SiCl4(s) would have the highest. Is my answer correct? Thank you!! 
physics concept
Nevermind i was right 
physics concept
An astronaut who is floating freely through space is seated upon a unicycle. He begins to pedal the unicycle “forward.” As he does so,what would the astronauts' motion be in space? Would he rotate in the opposite direction of the spinning wheel? 
Economics(Please respond)
Given the increase in government expenditures and the marginal propensity to consume, how would you find the change in equilibrium GDP? I did the expenditures X the marginal propensity but this is wrong. 
language arts
i need help depicting a poem using literary terms. The poem is Dear Sister and goes: Do not believe what all you read in the papers, Leona, about the strikers being reds. It is true, the Communist Party of New York sent down a truckload of potatoes. You will find them rotted ... 
Chemistry(Please check)
.50  x / x = 3.20e1 I need to solve for x. I was going to do .50 X 3.20e1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help. Math(Please help)  Reiny, Tuesday, April 17, 2012 at 3:18pm You probably meant (.50  x)/x = ... 
Chemistry(Please respond)
Step 1:H2O2 + I^^ = H2O + OI^^ step 2: H2O2 + OI^^ = H2O + O2 + I^^ What is the equation for the overall reaction? I am not sure how to do this since there are two equations. Complete the rate law for the overall reaction. I know how to do this one but I am not sure of ... 
Math(Please respond)
.50  x / x = 3.20e1 I need to solve for x. I was going to do .50 X 3.20e1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help. Math(Please help)  Reiny, Tuesday, April 17, 2012 at 3:18pm You probably meant (.50  x)/x... 
Chemistry
Please disregard question. 
Chemistry
A 21.2mL sample of 0.307M ammonia, NH3 is titrated with 0.259 M hydrobromic acid. What is the pH before the addition of any hydrobromic acid? I am not sure how to start this. I know I could completeit if I knew where to start. Would I set up a moles table? 
Chemistry(Please respond)
Calculate the pH of an aqueous solution of 0.15 M potassium carbonate. I know that pH = log(H30+) but I am not sure how to start this problem. Chemistry(Please help)  DrBob222, Saturday, April 14, 2012 at 11:09pm Hydrolyze the CO3^2. CO3^ + HOH ==> HCO3^ + OH^ Do an ... 
Chemistry(Please respond, thank you)
Step 1:H2O2 + I^^ = H2O + OI^^ step 2: H2O2 + OI^^ = H2O + O2 + I^^ What is the equation for the overall reaction? I am not sure how to do this since there are two equations. Which species acts as a catalyst? I know that I^^ is the catalsyt. Which species acts as a ... 
Math(Please help)
.50  x / x = 3.20e1 I need to solve for x. I was going to do .50 X 3.20e1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help. 
Chemistry(Thank you for your help)
Step 1:H2O2 + I^^ = H2O + OI^^ step 2: H2O2 + OI^^ = H2O + O2 + I^^ What is the equation for the overall reaction? I am not sure how to do this since there are two equations. Which species acts as a catalyst? I know that I^^ is the catalsyt. Which species acts as a ... 
Chemistry(Please help)
How do I set up an ice table when I only have .15M? 
Chemistry(Please help)
Calculate the pH of an aqueous solution of 0.15 M potassium carbonate. I know that pH = log(H30+) but I am not sure how to start this problem. Chemistry(Please help)  DrBob222, Saturday, April 14, 2012 at 11:09pm Hydrolyze the CO3^2. CO3^ + HOH ==> HCO3^ + OH^ Do an ... 
History, World
How many innocent South Vietnamese citizens were killed during the Vietnam war? 
Chemistry(Please help)
Calculate the concentration of HC6H6O6 in an aqueous solution of 0.0851 M ascorbic acid, H2C6H6O6 (aq). I do not know how to start this 
physics
Calculate the power of a device that requires 1.98 mA at 25.5 V. I know how to do the problem. i am just confused on how to convert megaAmps(which is mA right?) to amps. i think there are 1million amps in one mega amp? is that correct or is it the other way. so would you do 1.... 
Chemistry
What is the percent by weight of a solution prepared by dissolving 25 g of NaCl in 150 g of water? What is the volume of water in a 1 L bottle of 37% rubbing alcohol by volume? 
Chemistry
A buffer solution is prepared by adding 14.37g of NaC2H3O2 and 16.00g of acetic acid to enough water to make 500mL of solution. What is the initial concentration of C2H3O2 in the solution? Ka(HC2H3O2)=1.8e5 HC2H3O2 = H3O+ + c2h3O2 the molar mass of NaC2H3O3 = 82.04 I know ...