Friday
December 19, 2014

Posts by sarah


Total # Posts: 4,457

physics
There is a relationship between momentum and energy KE = 1/2mv^2 p = mv m = p/v KE = 1/2 (p/v)v^2 KE = 1/2 pv From wiki answers The relation between kinetic energy is proportional to the square of velocity. Momentum is directly proportional to velocity. If the momentum of an ...
October 19, 2013

Physics
Find the potential energy when x = 0 or x = -1 Then using this energy then find speed using KE = 1/2mv^2 m = 1 kg
October 18, 2013

Math- Urgent
1/4 w=13 What does w equal? Please show all work.
October 16, 2013

Math- Urgent
Thank you.
October 16, 2013

Math- Urgent
Thank you. I have one more question. 1/4 w=-13
October 16, 2013

Math- Urgent
15=y+24 What does y equal? Please show all work.
October 16, 2013

History
Those are all good ideas. Thank you!!
October 14, 2013

History
My text doesn't say specifically anything, but I have to infer. For Portugal I found four things, but for Spain I only thought of that they had strong armies, they wanted to find the Spice Islands, and that they wanted to spread Christianity to non-Christian areas.
October 14, 2013

History
What are some factors that are responsible for the emergence of Portugal and Spain as the most dominant powers of Europe during the early 16th century? Make sure to have multiple factors for each country.
October 14, 2013

math
Anyone can help me on this qns? The Fourier series expansion for the periodic function,f(t) = |sin t|is defined in its fundamental interval. Taking π = 3.142, calculate the Fourier cosine series approximation of f(t), up to the 6th harmonics when t = 1.09. Give your ...
October 13, 2013

maths
make x the subject 1/4wxy-p=k
October 13, 2013

Maths
t (1/8x+p)=m Make x the subject
October 13, 2013

Fourier Series
A periodic function f(t), with period 2π is defined as,f(t) = c for 0 < t < πf(t) = -c for -π < t < 0where c = 1.4, Taking π = 3.142, calculate the Fourier sine series approximation up to the 5th harmonics when t = 1.63. Give your answer to 3 ...
October 13, 2013

Physics
I really don't get why I am getting this question wrong? Please can you explain to me how to do this question step by step so that I can understand it please? :( i have been stuck on this question for quite a while now. Determine the stopping distances for an automobile ...
October 11, 2013

Physics
I really don't get why I am getting this question wrong? Please can you explain to me how to do this question step by step so that I can understand it please? :( i have been stuck on this question for quite a while now. Determine the stopping distances for an automobile ...
October 11, 2013

Physics
I really don't get why I am getting this question wrong? Please can you explain to me how to do this question step by step so that I can understand it please? :( i have been stuck on this question for quite a while now. Determine the stopping distances for an automobile ...
October 11, 2013

Physics
I really don't get why I am getting this question wrong? Please can you explain to me how to do this question step by step so that I can understand it please? :( i have been stuck on this question for quite a while now. Determine the stopping distances for an automobile ...
October 11, 2013

Science
What is the relationship between the number of gas particles and pressure. Are these two variables directly proportional or do they vary inversely?
October 9, 2013

algebra
Can you help me solve for like terms: x - 14y + 3x - 1 2 - 10x - 3 + y 19x - 3y - 37 - y
October 9, 2013

Macolm X
2011–2012 seasons, Patrice Bergeron entered a game against the Ottawa Senators with a plus/minus rating of +20. In the game, which Boston won 4–3; Bergeron was on the ice for one of his team's qualifying goals as well as all three qualifying goals by the Senators...
October 7, 2013

Chemistry
Calculate the molarity of a solution made by adding 28.2 mL of concentrated ammonia (28.0 % by mass, density 0.880 g/mL) to some water in a volumetric flask, then adding water to the mark to make exactly 500 mL of solution. (It is important to add concentrated acid or base to ...
October 7, 2013

Physics
A track star in the long jump goes into the jump at 12 m/s and launches herself at 20.0° above the horizontal. How long is she in the air before returning to Earth? (g = 9.81 m/s2)
October 6, 2013

Math: Pre-calculus
A rancher wants to build a rectangular pen with an area of 180 . Let W be the width of the pen and L be the length of the pen. a) Find an equation for the perimeter P in terms of W and L . b) Use the given area to write an equation that relates W and L . c) Find the pen ...
October 6, 2013

Math- urgent
What is (6.91 x 10-2 power) + (2.4 x 10-3 power) ? Express your answer in scientific notation.
October 3, 2013

Physics
. A package sitting on a shelf is knocked off. The velocity of the box just before it hits the floor is 8.5 m/s. Calculate the height of the shelf using; A displacement/velocity/acceleration equation Conservation of energy and hence show that these two methods produce the same...
October 2, 2013

Physics
A particular task exposes the operator to alpha radiation at an average dose of 200 ìGy each time the task is performed. If the company needs the task performed once per day over a 250-day working year and the maximum occupational dose limit is 20mSv per year, how many ...
October 1, 2013

physics
This is an example question which I have the answer to but can not seem to get the same answer through my workings, any help with the equation would be great. A particular task exposes the operator to alpha radiation at an average dose of 200 ìGy each time the task is ...
October 1, 2013

Math
Emma is 5 years older than 6 times beth's age. If Emma is 29 years old how old is Beth?
October 1, 2013

check my work on derivatives
Can someone check my work? So, I took the derivative of (1-x^2)/((1+x^2)^2) I used the quotient rule ((2x((1+x^2)^2)-2((1+x^2)^2)(2x)(1-x^2))) / ((1+x^2)^4) Then I simplified it (2x+2x^2 - 4x((1+x^2)^2)(1-x^2)) /((1+x^2)^4) Then I simplified by factoring out some numbers 2x(x^...
September 30, 2013

physics
A motorist travelling at 82 km/hr is being chased by a police car at 121 km/hr. If the police car starts from 4.0 km back, how long does it take to catch the motorist? Leave time in hours.
September 30, 2013

geometry
what is a concave polygon using the classify and differentiate method
September 26, 2013

Chemistry
A volume of 60.0mL of aqueous potassium hydroxide (KOH ) was titrated against a standard solution of sulfuric acid (H 2 SO 4 ). What was the molarity of the KOH solution if 25.7mL of 1.50 M H 2 SO 4 was needed? The equation is 2KOH(aq)+H 2 SO 4 (aq)¨K 2 SO 4 (aq)+2H ...
September 26, 2013

Physics 2 College Level
A cylinder is closed at both ends and has insulating walls. It is divided into two compartments by an insulating piston that is perpendicular to the axis of the cylinder as shown in Figure a. Each compartment contains 1.00 mol of oxygen that behaves as an ideal gas with γ...
September 17, 2013

grammar fast plz
Well then it will be just freshmen. So you would say "...YOU, the freshmen-class of 2017.
September 17, 2013

Chemistry
We did a flame test today to see what substances produce what colors when burned. Can you please explain... Why each of the different elements have a different atomic emission spectrum? Would the flame tests be useful for detecting individual elements present in a mixture of ...
September 17, 2013

Math urgent
Oh I understand now. Thank you so much!
September 16, 2013

Math urgent
Thank you! Could you please show your work to how you got to 1/10? It would be easier to explain to my class.
September 16, 2013

Math urgent
What is 4.1 repeating written as a fraction? I don't know if it should be written over 100 or over 10.
September 16, 2013

Chemistry
Orange light has a frequency of 4.8 x 10^14 s^ -1. What is the energy of one quantum of orange light?
September 16, 2013

Economic
Who has an unlimited checking account with the US Treasurer that enables them to write all the checks they want without regard to having funds in the bank?
September 14, 2013

Science
Helium doesn't react with any other substance. Is it accurate to say that helium has no chemical properties? Explain. Please help because I'm not sure of the answer. Thank you.
September 13, 2013

Science
*IM SORRY I MEANT SCIENCE FOR THE SUBJECT.
September 13, 2013

History
Helium doesn't react with any other substance. Is it accurate to say that helium has no chemical properties? Explain. Please help because I'm not sure of the answer. Thank you.
September 13, 2013

AP Calculus
I asked this yesterday and someone answered. but i didn't understand the explanation.. Two circles of radius 4 are tangent to the graph of y^2=4x at the point (1,2). Find equations of these two circles. I got (x-1)^2+(y-2)^2=16 and (x-4.36)^2+(y+1.36)^2=16
September 12, 2013

Math
plug in 4 for x, and -3 for y. 4-4(-3)/2 4+12/2 16/2 8
September 12, 2013

math
At 4 pm, Jack who is 6 ft tall cast a shadow that is 4 1/2 ft long. At the same time, a nearby free cast a shadow that is 12 ft long, how tall is the tree?
September 12, 2013

AP Calculus
A projectile fired upward from ground level is to reach a maximum height of 1,600 feet. What is its initial velocity?
September 11, 2013

AP Calculus
Two circles of radius 4 are tangent to the graph of y^2=4x at the point (1,2). Find equations of these two circles. I found the derivative of y^2=4x, but i don't know what to do next!
September 11, 2013

Computer Science
The array represents a map with coins, and the integers represent a row and column location of a coin gatherer. The gatherer is greedy and lazy when deciding to which adjacent location (either up, down, left, right) to move next. It’s greedy because it moves to the ...
September 8, 2013

Physics
A firefighter 41.8m away from a burning building, directs Zach stream of water from a ground level fire hose at an angle of 33.0 degrees above the horizontal . If the speed of the streams it leaves the hose is 42.7m/s, at what height will the stream of water hit the building
September 8, 2013

Physics
Suppose a single electron orbits about a nucleus containing two protons (+2e), as would be the case for a helium atom from which one of the two naturally occurring electrons is removed. The radius of the orbit is 2.65 10-11 m. Determine the magnitude of the electron's ...
September 8, 2013

Physics
A circular surface with a radius of 0.058 m is exposed to a uniform external electric field of magnitude 1.49 104 N/C. The electric flux through the surface is 74 N · m2/C. What is the angle between the direction of the electric field and the normal to the surface?
September 8, 2013

Physics
In the rectangle in the drawing, a charge is to be placed at the empty corner to make the net force on the charge at corner A point along the vertical direction. What charge (magnitude and algebraic sign) must be placed at the empty corner? (the rectangle has +3 uC charges in ...
September 8, 2013

Physics
Suppose a single electron orbits about a nucleus containing two protons (+2e), as would be the case for a helium atom from which one of the two naturally occurring electrons is removed. The radius of the orbit is 2.65 10-11 m. Determine the magnitude of the electron's ...
September 8, 2013

Math
A projectile is fired with an initial velocity of v0 feet per second. The projectile can be pictured as being fired from the origin into the first quadrant, making an angle O with the positive x-axis. If there is no air resistance, then at t seconds the coordinates of the ...
September 8, 2013

Physics
Suppose a single electron orbits about a nucleus containing two protons (+2e), as would be the case for a helium atom from which one of the two naturally occurring electrons is removed. The radius of the orbit is 2.65 10-11 m. Determine the magnitude of the electron's ...
September 6, 2013

Physics
A circular surface with a radius of 0.058 m is exposed to a uniform external electric field of magnitude 1.49 104 N/C. The electric flux through the surface is 74 N · m2/C. What is the angle between the direction of the electric field and the normal to the surface?
September 6, 2013

physics
A is the bottom left corner. The empty corner is the top right corner.
September 6, 2013

physics
In the rectangle in the drawing, a charge is to be placed at the empty corner to make the net force on the charge at corner A point along the vertical direction. What charge (magnitude and algebraic sign) must be placed at the empty corner? (the rectangle has +3 uC charges in ...
September 6, 2013

Physics
Two point charges are fixed on the y axis: a negative point charge q1 = -26 µC at y1 = +0.21 m and a positive point charge q2 at y2 = +0.30 m. A third point charge q = +8.5 µC is fixed at the origin. The net electrostatic force exerted on the charge q by the other ...
September 6, 2013

Physics
A circular surface with a radius of 0.058 m is exposed to a uniform external electric field of magnitude 1.49 104 N/C. The electric flux through the surface is 74 N · m2/C. What is the angle between the direction of the electric field and the normal to the surface?
September 6, 2013

Physics
A circular surface with a radius of 0.058 m is exposed to a uniform external electric field of magnitude 1.49 104 N/C. The electric flux through the surface is 74 N · m2/C. What is the angle between the direction of the electric field and the normal to the surface?
September 6, 2013

Physics
The drawing shows a positive point charge +q1, a second point charge q2 that may be positive or negative, and a spot labeled P, all on the same straight line. The distance d between the two charges is the same as the distance between q1 and the spot P. With q2 present, the ...
September 6, 2013

Science
Outline a step-by-step method for determining the density of a baseball. Please help with this too! Thanks
August 31, 2013

Science
Estimate the length of a baseball bat and mass of a baseball in SI units. How can you check how close your estimates are? Please help! Thank you
August 31, 2013

Physics
When point charges q1=+8.4uC and q2=+5.6uC are brought near each other, each experiences a repulsive force of magnitude 0.66N. Determine the distance between the charges.
August 28, 2013

Physics
When point charges q1=+8.4uC and q2=+5.6uC are brought near each other, each experiences a repulsive force of magnitude 0.66N. Determine the distance between the charges.
August 28, 2013

Physics
When point charges q1=+8.4uC and q2=+5.6uC are brought near each other, each experiences a repulsive force of magnitude 0.66N. Determine the distance between the charges.
August 28, 2013

Physics
Displacement vector A points due east and has a magnitude of 2.26 km. Displacement vector B points due north and has a magnitude of 2.62 km. Displacement vector C points due west and has a magnitude of 2.6 km. Displacement vector D points due south and has a magnitude of 2.6 ...
August 26, 2013

Maths
Heather loves roses.In her rose garden she has half as many pink roses as red,and four times as many red ones as white.There are 37 roses that are either yellow or white.Twenty are yellow.How many roses are in Heather's garden? Help me out please anyone
August 24, 2013

Maths
Twenty-four ladybirds were sitting at various places around the garden.One sixth of the ladybirds flew away to settle in the garden.Half of the remaining ladybirds sat on a yellow sunflower.Then half of those on the sunflower flew onto a fence post.There were no ladybirds on ...
August 24, 2013

Maths
Twenty-four ladybirds were sitting at various places around the garden.One sixth of the ladybirds flew away to settle in the garden.Half of the remaining ladybirds sat on a yellow sunflower.Then half of those on the sunflower flew onto a fence post.There were no ladybirds on ...
August 24, 2013

Math
Let F(x)= X^2+ 5 and G9x)= (x+1) / (x-1). Find (a) F-3G and (b) F(g(x))
August 22, 2013

Math
I really want to understand factoring, and I have a problem and the answer but I don't understand the steps to getting an answer. 3x^5-12^4+18x^3
August 22, 2013

Biology (Science)
Which of the following is not true about a hypothesis? 1) Previous knowledge can help support it. 2) It is a tentative explanation. 3) It can be proven to be false. 4) It must be testable to be useful. 5) It can be proven to be true. I know for sure that 2 and 4 is not the ...
August 21, 2013

Biology (Science)
John uses mechanical "predators" to approach frogs at a pond shore, and he records the distance between predator and frog as the frogs jump. (PEER REVIEW) On a walk around pond John sees that small frogs on the shore only allow him to get within 5 feet before jumping...
August 21, 2013

Math
Find an equation of the tangent line to the circle x^2+y^2=25 at the point (4,-3)
August 20, 2013

MAth
Is this undefined?
August 20, 2013

MAth
find equation of line which passes through the points (5,7) and (5,-8).
August 20, 2013

leadership
In your leadership model, what are the a leader's most important task? What are the core values that your leadership model emphasized?
August 15, 2013

leadership
what are the core values that your leadership model emphasizes? In what ways does my leadership model reflect existing scholarship on leadership and in what ways is my approach unique to me? what barriers and opportunities exist towards the implementation of my personal ...
August 15, 2013

chemistry
no im wrong, the ph will not decrease.
August 13, 2013

chemistry
Can the ph of a buffer solution of potassium hydroxide decrease when exposed to air overnight? I'm pretty sure the answer is yes
August 13, 2013

Chemistry
If you have a di or polyprotic buffer state below whether you see evidence of this in the form of your pH curve. If you do not see evidence of this, explain why this should be the case Wouldn't you see evidence of a di or polyprotic buffer if there are multiple ...
August 13, 2013

physics
A hot-air balloon is rising upward with a constant speed of 2.80 m/s. When the balloon is 9.48 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?
August 13, 2013

chemistry
I do mean spilled, thanks.
August 7, 2013

chemistry
That is excellent thank you. Now you have given me the answer working through it myself makes a lot more sense. Can you help me with the one below as well. A 25.0 mL solution of HCl has been spilt. It took 21.8 mL of saturated 2.5 M NaOH to neutralise the acid. What was the ...
August 7, 2013

chemistry
Can one calculate the number of moles of air? If so, calculate the number of moles in 1 kg of air (making sure your calculation, units and assumptions are fully explained); If not, explain why it is not possible to calculate the number of moles of air.
August 7, 2013

chemistry
A 25.0 mL solution of HCl has been spilt. It took 21.8 mL of saturated 2.5 M NaOH to neutralise the acid. What was the molar concentration of the acid?
August 7, 2013

maths
Determine the acute angle between the line passing through the points A(-2;1/5) and B(0;1) and the line passing through the points C(1;0) and D(-2;6)
August 6, 2013

Physics
Why is it highly unlikely to find an ion with a charge less than -4 or greater than +4? I need examples of different types of ions and evidence to support the logic using the concepts of ionization energy and electronegativity.
August 6, 2013

Math
during the warranty period, 6% of their computers are returned because they have defective keyboards, 5% are returned because they have defective disk drives, and 1% are returned because both the keyboard and the disk drive are defective. What is the probability that a ...
July 27, 2013

math
sorry,i 'm not understand the number 4,4,4 either
July 27, 2013

math
complete the pattern : 1/2 , 3/4 , 1 , 4 , 4 , 4
July 27, 2013

math
it's the right answers,that's why i cannot figure it out
July 27, 2013

math
the iceman found recently in a glacier was a first thought to be about 5300 years old.Roughly when did he have his 14th birthday?2700bc,300bc,3700bc,5300bc or 7300bc
July 27, 2013

math
i don't understand what is x of y alone ,
July 27, 2013

math
if a number x is 10%of y and z,and z is 3 times of y.What % is x of y alone? 1)3.3% 2)2.5% 3)5% 4)4%
July 27, 2013

math
complete the pattern:50,20,8,4,4,4.
July 23, 2013

Spain History
I'm doing a survey for my class to get opinions to see which side people favored the most, the Nationalists or the Republicans? I have interviewed the people I know but I'm still lacking.
July 23, 2013

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