Saturday

February 28, 2015

February 28, 2015

Total # Posts: 3,003

**Physics(Please respond)**

1) A roller coaster (398 kg) moves from A (3.82 m above the ground) to B (29.4 m above the ground). Two non-conservative forces are present: friction does -1.82 x 104 J of work on the car, and a chain mechanism does +5.49 x 10^4 J of work to help the car up a long climb. What ...
*June 2, 2012*

**Physics(Please help)**

So for v would I do sqrt(2*11.9*9.8*0.0458) ?
*June 1, 2012*

**Physics(Please help)**

A skier slides horizontally along the snow for a distance of 11.9 m before coming to rest. The coefficient of kinetic friction between the skier and the snow is 0.0458. Initially, how fast was the skier going? I do not know how to start this. Thank you.
*June 1, 2012*

**Physics(Please respond)**

So for m I would plug in 71kg correct?
*June 1, 2012*

**Physics(Please respond)**

so for m
*June 1, 2012*

**Physics(Please respond)**

A student, starting from rest, slides down a water slide. On the way down, a kinetic frictional force (a nonconservative force) acts on her. The student has a mass of 71 kg, and the height of the water slide is 12.0 m. If the kinetic frictional force does -7.4 × 103 J of...
*June 1, 2012*

**Physics(Please respond)**

A 12-kg crate is pushed up an incline from point A to point B. What is the change in the gravitational potential energy of the crate? Point A is 2.0m and point b is 7.0m I am not sure how to start this.
*May 31, 2012*

**Precalculus check answers help!**

Were these right???????
*May 31, 2012*

**Physics(Please respond)**

I did the math wrong, I got 103 now.
*May 30, 2012*

**Physics(Please respond)**

Is that correct?
*May 30, 2012*

**Physics(Please respond)**

so on the left side of the equation the mass is gone and on the right side the mass and gravity is gone. So the anwser would be 784h = 1800 h=2.2
*May 30, 2012*

**Physics(Please respond)**

a rollar coaster is 80m high and has a 50kg car at rest. Ignore air resistance and friction. If the speed of the car is 60m/s what is the height? 0+50(9.8)(80) = 1/2(50)(vf^2) + (60)^2 + 50(9.8)(h). Is this equation correct?? If so I do not know how to solve for h since on the...
*May 30, 2012*

**Physics(Please respond)**

so m=1320kg and v=3.32^2 but what is r and mg?
*May 29, 2012*

**Physics(Please respond)**

1) A 1320 kg demolition ball swings at the end of a 34.3 m cable on the arc of a vertical circle. At the lowest point of the swing, the ball is moving at a speed of 3.32 m/s. Determine the tension in the cable. F=ma (34.3)(3.32) = 113.87 Ia this correct?
*May 29, 2012*

**Physics(Please help)**

A jet flying at 106 m/s banks to make a horizontal circular turn. The radius of the turn is 3810 m, and the mass of the jet is 2.40 × 105 kg. Calculate the magnitude of the necessary lifting force. Would I use the equation Fc=mv^2 / r ??
*May 29, 2012*

**Physics(Please help)**

1) A box is sliding up an incline that makes an angle of 14.0 ° with respect to the horizontal. The coefficient of kinetic friction between the box and the surface of the incline is 0.176. The initial speed of the box at the bottom of the incline is 3.72 m/s. How far does ...
*May 29, 2012*

**Physics(Please respond)**

A golfer hits a shot to a green that is elevated 3.0 m above the point where the ball is struck. The ball leaves the club at a speed of 17.4 m/s at an angle of 35.0¢ª above the horizontal. It rises to its maximum height and then falls down to the green. Ignoring air ...
*May 29, 2012*

**Physics(Please respond)**

A golfer, standing on a fairway, hits a shot to a green that is elevated 5.33 m above where she is standing. If the ball leaves her club with a velocity of 48.0 m/s at an angle of 35.7 ° above the ground, find the time that the ball is in the air before it hits the green...
*May 28, 2012*

**Physics(Please respond)**

I meant (17 sin 35)^2
*May 28, 2012*

**Physics(Please respond)**

so for vy I would do (17.4 sin 35) - 2(9.8)(3) ??
*May 28, 2012*

**Physics(Please respond)**

A golfer hits a shot to a green that is elevated 3.0 m above the point where the ball is struck. The ball leaves the club at a speed of 17.4 m/s at an angle of 35.0¢ª above the horizontal. It rises to its maximum height and then falls down to the green. Ignoring air ...
*May 28, 2012*

**Physics(Please respond)**

so is 79.2 kg the value for mass(m) or mg?
*May 28, 2012*

**Physics(Please respond)**

A 79.2-kg person stands on a scale in an elevator. What is the apparent weight when the elevator is (a) accelerating upward with an acceleration of 1.92 m/s2, (b) moving upward at a constant speed, and (c) accelerating downward with an acceleration of 1.89 m/s2 I was going to ...
*May 28, 2012*

**Physics(Please respond)**

A golfer hits a shot to a green that is elevated 3.0 m above the point where the ball is struck. The ball leaves the club at a speed of 17.4 m/s at an angle of 35.0¢ª above the horizontal. It rises to its maximum height and then falls down to the green. Ignoring air ...
*May 28, 2012*

**Physics(thank you for the help)**

A hot-air 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 ...
*May 27, 2012*

**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, ...
*May 27, 2012*

**Physics(thank you for the help)**

I do not know how to solve for a ratio.
*May 27, 2012*

**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 ...
*May 27, 2012*

**Physcis(Please help)**

A pilot flies her route in two straight-line 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 ...
*May 27, 2012*

**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 ...
*May 27, 2012*

**Physics(Please help)**

When I put 21.792 m/s as my answer my online homework said it was incorrect. Why??
*May 27, 2012*

**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.
*May 27, 2012*

**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.
*May 27, 2012*

**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...
*May 27, 2012*

**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.
*May 26, 2012*

**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?
*May 26, 2012*

**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!
*May 26, 2012*

**Physics(Please help)**

How do you know when to use tan instead of cos or sin?
*May 25, 2012*

**Physics(Please help)**

1) two hot-air 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...
*May 25, 2012*

**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.
*May 25, 2012*

**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...
*May 25, 2012*

**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 ?
*May 25, 2012*

**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...
*May 25, 2012*

**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...
*May 23, 2012*

**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. ...
*May 23, 2012*

**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!
*May 23, 2012*

**pre calculs**

Is that supposed to be f(x)=3x^2-7x-2?
*May 23, 2012*

**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.
*May 22, 2012*

**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 ...
*May 22, 2012*

**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 14-6 = 8. There are 8 neutrons in an atom of carbon with a mass number of 14.
*May 22, 2012*

**Chemistry**

Why do chloride ions increase corrosion?
*May 22, 2012*

**Physics**

Thank you!!
*May 21, 2012*

**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 ...
*May 21, 2012*

**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?
*May 21, 2012*

**Physics(Please help)**

thank you!
*May 21, 2012*

**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 ...
*May 21, 2012*

**Math**

The circumference of hte front tire is 6ft. How many complete turns does the front wheel make in 30 ft driveway?
*May 18, 2012*

**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.
*May 17, 2012*

**Physics(Please check)**

I know the highest point would be 29.4 but I do not know how to get this.
*May 16, 2012*

**Physics(Please check)**

Ok but where did the 9 come from?
*May 16, 2012*

**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.
*May 16, 2012*

**Physics(Please check)**

A 5-kg 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.
*May 16, 2012*

**Physics(Please check thanks)**

Thank you!
*May 16, 2012*

**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?
*May 16, 2012*

**Physics(Please respond)**

why is sin negative?
*May 16, 2012*

**Physics(Please respond)**

Vector A has a magnitude 2.4m and direction 130 degrees relative to the positive x-axis. Vector B has magnitude 3.0m and direction 250 degrees relative to the positive x-axis. 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...
*May 16, 2012*

**math**

ok thank you!
*May 12, 2012*

**math**

4 and 505/1000. but how does that help with this?
*May 12, 2012*

**math**

calculate 10^1.27 how do i do this?
*May 12, 2012*

**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?
*May 9, 2012*

**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...
*May 3, 2012*

**physics**

is increasing the current a valid method to increase the induced voltage when a magnet moves into a solenoid?
*May 1, 2012*

**Chemistry(Please help)**

0.0885 - x = 4.2e-7 Then I added 0.0885 to the right side and got 8.85e-2. Would this be the concentration or do I need to do another step?
*April 29, 2012*

**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?
*April 29, 2012*

**Chemistry(Please respond)**

I multiplied 0.119 by 1.58e-10 and then took the square root, is that correct?
*April 29, 2012*

**Chemistry(Please respond)**

I did 1.0e-14 / 6.3e-5 = 1.58e-10 Then would I do (1.58e-10)(0.119)?
*April 29, 2012*

**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 2.39e-2 = 6.76e-3 Then I did 6.76e-3 / 0.207 = 3.36e-2 2.39e-2 + 3.36e-2 = 5.65e-2 6.76e-3/5.65e-2 = 0.119 I do ...
*April 29, 2012*

**surface area and volume**

number 2 is wrong its b. 707 yd^2.
*April 29, 2012*

**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^...
*April 28, 2012*

**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 didnt give me the correct answer. Chemistry(Please help) - Dev, Wednesday, April 25, 2012 at 6:56pm ...
*April 28, 2012*

**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?
*April 26, 2012*

**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
*April 25, 2012*

**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??
*April 25, 2012*

**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 didnt give me the correct answer.
*April 25, 2012*

**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?
*April 24, 2012*

**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...
*April 24, 2012*

**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?
*April 23, 2012*

**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 ...
*April 23, 2012*

**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=8.314e-3kJ/K mol -delta Go / RT I did -29.10 / 8.314e-3 X 298K and -11.74 but this was wrong. I am stuck. What did I do wrong?
*April 23, 2012*

**Chemistry(Please check answers)**

1) The standard molar entropy value of N2 (g) is 191.5 J/K-mol, of O2 (g) is 205.0 J/K-mol and of NO2 (g) is 240.0 J/K-mol. 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...
*April 23, 2012*

**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?
*April 23, 2012*

**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 ...
*April 23, 2012*

**Chemistry**

Thank you.
*April 23, 2012*

**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 2.49e-1 instead 3.20e-1. I understand everything except how did you...
*April 23, 2012*

**Chemistry**

.50 - x / x = 3.20e-1 I need to solve for x. I was going to do .50 X 3.20e-1 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...
*April 23, 2012*

**Chemistry(Please check)**

Thank you!
*April 23, 2012*

**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?
*April 23, 2012*

**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 ...
*April 23, 2012*

**Chemistry(Please check)**

Now that I looked over this question again I agree with that too. Thank you!
*April 22, 2012*

**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?
*April 22, 2012*

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