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December 21, 2014

Posts by help


Total # Posts: 966

physics
i read the question wrong..thank for the help
November 29, 2010

physics
A 45.00 kg child standing on a frozen pond throws a 0.60 kg stone to the east with a speed of 5.80 m/s. Neglecting friction between child and ice, what is the speed (in m/s) of the child after throwing the stone? I'm kind of confused about the masses..
November 29, 2010

CAL 1
DERIVATIVE f(x)=4t+1 (x,x+2)
November 28, 2010

cal 1
Find the area of the indicated region f(x)=(4-x^2) between(0,2)with 4 equal subintervals (left endpoints)
November 27, 2010

math
find all points on the hyperbola y=1/x, that are closest to the origin on (1/2,2)
November 27, 2010

cal 1
f(x)= (1-sinx) interval (0≤x≤2π) find where the function is increasing decreasing.. i know that f`(x)=1-sinx it is equal to zero when x=pi/2 im stuck there..
November 26, 2010

chemistry
oops..i posted this question twice
November 25, 2010

chemistry
a 5.55g sample of a weak acid with ka=1.3*10^-4 was combined with 5.00ml of 6.00 M NAOH and the resulting solution was diluted to 750mL. The measured pH of the solution was 4.25. what is the molor mass of the weak acid. if used the formula pH=kpa+log(base/acid) Ph=3.89+log(6....
November 25, 2010

chemistry
a 5.55g sample of a weak acid with ka=1.3*10^-4 was combined with 5.00ml of 6.00 M NAOH and the resulting solution was diluted to 750mL. The measured pH of the solution was 4.25. what is the molor mass of the weak acid. if used the formula pH=kpa+log(base/acid) Ph=3.89+log(6....
November 25, 2010

chemistry
A 20ml sample of .125M diprotic acid solution was titrated with .1019M KOH.the constants for the acid are k1=5.2*10 ^-5 and K2=3.4*10 ^-10. What added volume of base does each equivalence point occur? i got .0254L for the first one and .0508 for the second. Can anyone check if...
November 24, 2010

physics
What is the original compression distance of the spring? Thought it would be zero but that isn't right.
November 23, 2010

physics
a 3.5 kg block is accelerated from rest by a compressed spring of spring constant 640 N/m. The block leaves the spring at the springs relaxation length.The block then travels over a horizontal floor with coefficient of kinetic friction 0.25. The friction force stops the block...
November 23, 2010

physics
never mind i got the question:)
November 23, 2010

physics
A 2.606 kg block is on a horizontal surface with ìk = 0.160, and is in contact with a lightweight spring with a spring constant of 577 N/m which is compressed. Upon release, the spring does 7.212E-1 J of work while returning to its equilibrium position. I found the ...
November 23, 2010

physics
the next part is What is the speed of the block when it hits the spring? i did 1.42=.5mv^2(final)-.5mv^2(initail) The final velocity woulf be zero so 1.42=.5(2.8)v^2 v=1.01 im not sure what i did wrong
November 23, 2010

physics
A moving 2.8 kg block collides with a horizontal spring whose spring constant is 215 N/m (see figure). The block compresses the spring a maximum distance of 11.5 cm from its rest position. The coefficient of kinetic friction between the block and the horizontal surface is 0.48...
November 23, 2010

physics
The force F = (3.2, -7.1) N acts on a mass of 1.15 kg. At time t = 0 s, the mass has a velocity v0 = (-0.46, 0.36) m/s. What is the initial kinetic energy (in J)? i know that k=.5mv^2 so the answer i got was (.12167,0.07452) but i'm not sure what to do from there?
November 22, 2010

physics
The force F = (3.2, -7.1) N acts on a mass of 1.15 kg. At time t = 0 s, the mass has a velocity v0 = (-0.46, 0.36) m/s. What is the angle (in degrees) of the initial velocity, measured counter-clockwise from the +x-axis? I got 38.04 degrees but isn't the right answer
November 21, 2010

physics
A 2.20 kg box slides down a rough incline plane from a height h of 1.39 m. The box had a speed of 2.77 m/s at the top and a speed of 2.34 m/s at the bottom. Calculate the mechanical energy lost due to friction
November 21, 2010

physics
A constant force of 48.7 N, directed at 34.1° from horizontal, pulls a mass of 15.1 kg horizontally a distance of 2.77 m. Calculate the work done by the force.
November 21, 2010

math
A painter leans a ladder against a vertical wall. The top of the ladder is 7 meters above the ground. When the bottom of the ladder is moved 1 meter farther away from the wall, the top of the ladder is 5 meters above the ground. What is the length of the ladder? Round to the ...
November 17, 2010

math
Three rectangles have exactly the same area. The dimensions of each rectangle (as length and width) are a and b; a – 3 and b + 2; and a + 3 and b – 1. Find the area of the rectangles.
November 17, 2010

math
Three rectangles have exactly the same area. The dimensions of each rectangle (as length and width) are a and b; a – 3 and b + 2; and a + 3 and b – 1. Find the area of the rectangles.
November 17, 2010

Physics
A cylinder with a piston is filled with ideal gas. The gas temperature is held at 450 K. The cylinder is heated by an oven through a square metal rod connected between the oven and the cylinder. The rod has sides d = 2 cm and length L = 2.3 m. (a) If the oven is held at 850 K...
November 16, 2010

chemistry
For all deexcitations that result in the visible spectrum of hydrogen, what is n ?
November 15, 2010

chemistry
The X-X bond energy in the hypothetical gas, X2 is 153 kJ/mol. a. How much energy, in joules, is required to break the bond in a single X-X molecule? b. What wavelength of electromagnetic radiation would have the energy required to break the X-X bond? c. In what region of the ...
November 15, 2010

chemistry
The red line in the Helium spectrum is longer than the red line in the hydrogen spectrum. What does that tell us about the distance between n2 and n3 in helium as compared with the distance between n2 and n3 in hydrogen?
November 15, 2010

chemistry
In the emission spectrum of hydrogen, some lines are in the infra red range. h l Suggest an electron transition (specify n and n) that is in this range and calculate its corresponding wavelength and delta E.
November 15, 2010

algebra
are you sure? thank you :)
November 10, 2010

bobpursley???
i did that and i also wrote the answers next to each question and i just want to know if they are right. are they right? please respond
November 10, 2010

science
what is the difference between a control and a variable
November 10, 2010

science
thank you :)
November 10, 2010

science
what is concentration plese say it in an easy to understand answer thank you!
November 10, 2010

8th grade
According to the U.S. Census Bureau in 2009 there were 21,854,374 veterans in the United States. Veterans of the Korean War accounted for 12.4% of that total, while 10.7% were veterans of World War II. What is the positive difference between the numbers of veterans of the ...
November 9, 2010

math
According to the U.S. Census Bureau in 2009 there were 21,854,374 veterans in the United States. Veterans of the Korean War accounted for 12.4% of that total, while 10.7% were veterans of World War II. What is the positive difference between the numbers of veterans of the ...
November 8, 2010

11th grade physics
the horizontal range of a projectile is 4 root 3 times of its maximum height. calculate the angle of projection.
November 8, 2010

11th grade physics
if action and reaction are always equal and opposite, why dont they always cancel each other and leave no force for acceleration of the body?
November 8, 2010

11th grade physics
find the value of 60 joule per minute on a system which has 10 cm,100gm, and 1 minute as fundamental units.
November 8, 2010

11th grade chemistry
thank you so much drbob222. u are a genius. could you check out my physics questions too?
November 8, 2010

11th grade chemistry
a vessel contains 12 gm of methane gas at t degree celcius temp. and 1 atm. pressure. when the temp. is increased by 10 degree celcius at the same volume, the pressure increases by 10%. calculate the volume and initial temp.
November 8, 2010

math
when is these rational function equal to zero? 6x^2/(x^3+1)^2=0 -2x/(x^2-1)^2=0
November 7, 2010

math
verify that the function satisfies the hypothesis of the mean value theorem on the given interval. then find all numbers c that satisfy the conclusion of the mean value theorem. f(x) = x/(x+2) , [1,4]
November 7, 2010

calculus
use the methods of this section to sketch the curve. y=x^3-3a^2x+2a^3, where a is a positive constant. What do the members of this family of curves have in common? How do they differ from each other?
November 7, 2010

Statistics
Are these statements true or false? 1. The sample mean, the sample proportion and the sample standard deviation are all unbiased estimators of the corresponding population parameters. 2. If the population is normally distributed with known variance then the sample mean may not...
November 5, 2010

math
what is the best parking space/shortest that would take the from store 1 to store 2 and back to the car?use the following information: -the distance between store 1 to store 2 is 25 yds wide. -driveway between the sidewalk and parking lot is 10 yds this all they give me please...
November 4, 2010

Math
y = |x − 4| + 8 Find the x-coordinate of the vertex of the graph. And the y-coordinate of the vertex of the graph. Please help me, I'm stuck!
November 3, 2010

HIstory
Why did congress feel that construction was a confessional task and not a presidential task?
November 3, 2010

spanish
what am i doing wrong??
November 1, 2010

spanish
¿Quién va a preparar la ensalada? Mirta y Lidia Your response: mirta y lidia las va a preparar 3.¿Quién va a cocinar la paella? Alberto y su novia Your response: alberto y su novia los va a cocinar. ¿Quién va a limpiar el apartamento ...
November 1, 2010

Halloween
It's saturday and halloweens tomorrow. But I was wondering is trick or treating sopost be today or tomorrow? I've heard peolple going today and many people say tomorrow. I know sunday is an school night and some people wiill be at church. I have no idea if I should ...
October 30, 2010

CALC HARD...
Suppose that 430 ft of fencing is used to enclose a corral in the shape of a rectangle with a semicircle whose diameter is a side of the rectangle. (In the figure below, the blue outline represents the fencing.) Find the dimensions of the corral with maximum area. x= y=
October 29, 2010

CALC HARD...
Suppose that 430 ft of fencing is used to enclose a corral in the shape of a rectangle with a semicircle whose diameter is a side of the rectangle. (In the figure below, the blue outline represents the fencing.) Find the dimensions of the corral with maximum area. x=? y=? i ...
October 29, 2010

CALC HARD...
i did get that and i got farther than that but then got completely lost
October 29, 2010

CALC HARD...
Suppose that 430 ft of fencing is used to enclose a corral in the shape of a rectangle with a semicircle whose diameter is a side of the rectangle. (In the figure below, the blue outline represents the fencing.) Find the dimensions of the corral with maximum area. x=? y=? i ...
October 29, 2010

chemistry
consider the following reactions O+N2->NO+N Ea=315kj/mol Cl+H2->HCl+H Ea=23kj/mol Why is the activation energy for one much lower that the other. The frequency factor is very close in value for the two. Assume they are the same compute the ratio of the reaction constants...
October 29, 2010

cant post a question
i tried posting a question but it says that i cant have links in my question but i didnt have any? Anyone know hat to do?
October 28, 2010

chem/math
thanks that helps alot
October 28, 2010

chem/math
I need to fid the activation energy but i forgot how to solve for Ea 4.58*10^-15=e^(Ea/2537.02) can you show the work thank you
October 28, 2010

Management
what economic, social , and political forces have made employee traininng even mor eimportant today than in the past?
October 28, 2010

calculus
find the absolute maximum and minimum values of f on the given interval f(x)= (x^2-4)/(x^2+4), [-4, 4]
October 28, 2010

chemistry
help
October 28, 2010

physics
Mary and John are on opposite sides of a seesaw. Mary has 3x the mass of John. If Mary is sitting at a distance of .5m from the fulcrum, how far must John site in order to keep it balanced.
October 27, 2010

calculus
Use a linear approximation (or differentials) to estimate the given number (2.001)^5
October 27, 2010

physics
A 70kg man stands on a bathroom scale in an elevator. As the elevator starts moving, the scale reads 90kg Is the elevator acceleration up or down, is the elevator moving up or down?
October 27, 2010

phsics can someone check if i did it right
A block of wood of mass 3kg is on a rough incline of 37degrees. Find the min value of the coefficient of static friction for the block to remain stationary? Fn=3*9.8cos37 Fn=23.4 3*9.8sin37-us(23.5)=0 us=.743
October 27, 2010

phsics
A block is at rest on an inclined plane whose elevation can be varied. The coefficient of static friction is μs= 0.4, and the coefficient of kinetic friction is μk = 0.16. The angle of elevation θ is increased slowly from the horizontal. At what value of θ ...
October 24, 2010

Stats-BOB PURSLEY Help, do you know this?
Is there a rule to figure out if this is a true or false statement? A sample size of 900 is not large enough to conclude that the sampling distribution of p is a normal distribution, when the estimate of the population proportion is .995.
October 24, 2010

Physical Science
Pitch is to make a plane descend or climb. The pilot adjusts the elevators on the tail to make a plane descend or climb. Lowering the elevators caused the airplane's nose to drop, sending the plane into a down. Raising the elevators causes the airplane to climb.
October 24, 2010

chemistry
Never mind i figured it out:)
October 24, 2010

chemistry
To what final volume should you dilute 50.5ml of a 4.75 M KI solution so that 27.5ml of the diluted solution contains 3.10g of KI
October 24, 2010

Ap Chemistry
:) Thanks you so much! :)
October 24, 2010

12th grade
Okay, sorry....I posted it again correctly :)
October 24, 2010

chemistry
Its just a general question. I'm trying to get the van't hoff factor and i think you need to know number of ions present. for example how do you know the # ions present in k2s
October 23, 2010

chemistry
How do you know the number of ions present in a compound.
October 23, 2010

Chemistry
Calculate the number of molecules in 3.1466x10^1 grams of sulfur dioxide, SO2
October 22, 2010

Chemistry
Calculate the number of molecules in 3.1466x10^1 grams of sulfur dioxide, SO2
October 22, 2010

Chemistry
calculate the grams of sodium in 17.606 g of Na2CO3
October 22, 2010

5th grade
88.8 or if you round 89
October 14, 2010

4th grade
all but a circle
October 14, 2010

Physics
A speedboat starts from rest and accelerates at 2.689x10^0 m/s2 for 6.5062x10^0 seconds. After that, the boat then accelerates at 1.7853x10^0 m/s 2 for 3.1299x10^0 seconds. What is the velocity of the boat at the end of this, expressed in 4 significant figures?
October 13, 2010

chemistry
please
October 13, 2010

chemistry
please
October 13, 2010

chemistry
Help please =)
October 13, 2010

math
math box! 5=15 10=25 15=35 20=45 25=55 what is the rule
October 13, 2010

science
try chicken wire
October 13, 2010

2nd grade
63
October 12, 2010

Physics
A car travels a total distance of 3.22911x10^2 m to the East in 6.7135x10^1 s. What is the speed of the car, in m/s with 4 significant figures? Note: Your answer is assumed to be reduced to the highest power possible. Your Answer: x10
October 12, 2010

math
how do yu find the implicit differentiation for this porblem 4cosx*siny=1
October 11, 2010

math
Find two point on a circle x^2+y^2=1 where the slope of the tangent line is -2 write the equation for the normal lines at these points.
October 10, 2010

math
For the given function, find all points on an the graph where the tangent line is horizontal or vertical. y= xsqrt(4-x^2) y= sqrt(1-x^2)(4-x^2)
October 10, 2010

chemistry
225g
October 1, 2010

chemistry
43g
October 1, 2010

chemistry
of KCl
October 1, 2010

chemistry
A solution was prepared by dissolving 43.0 of in 225 of water. Calculate the mass percent of in the solution.
October 1, 2010

math
how?
September 30, 2010

math
wat is the answer for the pattern 1,3,6?
September 30, 2010

physics
The flywheel of a steam engine runs with a constant angular speed of 164 rev/min. When steam is shut off, the friction of the bearings and the air brings the wheel to rest in 1.6 h. I found the constant angular acceleration as 1.71rev/min^2. They also ask you to find What is ...
September 28, 2010

Biochemistry
What is the net ionic equation for Phosphate ion + ammonium molybdate in the presence of nitric acid?
September 27, 2010

physics
A coin with a diameter of 1.9 cm is dropped on edge onto a horizontal surface. The coin starts out with an initial angular speed of 19 rad/s and rolls in a straight line without slipping. The rotation slows with an angular acceleration of magnitude 2.1 rad/s2. What is the ...
September 27, 2010

physics
The flywheel of a steam engine runs with a constant angular speed of 164 rev/min. When steam is shut off, the friction of the bearings and the air brings the wheel to rest in 1.6 h. I figured out the constant angular acceleration=1.71 rev/min2 but im not sure how to find:What ...
September 27, 2010

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