Saturday

January 31, 2015

January 31, 2015

Total # Posts: 973

**PHYSICS**

You accidentally throw your car keys horizontally at 10.0 m/s from a cliff 78 m high. How far from the base of the cliff should you look for the keys?
*December 11, 2010*

**physics**

an arrow of mass .04 kg is pulled back 10 cm in the bow, having a force of 25.2 N. It is released 1.5m from the ground...how far will the arrow fly? (all of the energy from pulling it back converts into the flying arrow)
*December 6, 2010*

**Physics **

Rubber Band A 156 g hockey puck is attached to a rubber band and rotated with an angular speed of 9.8 rad/s on frictionless horizontal ice. It takes a force of 1.12 N to stretch the rubber band by 1 cm. (a) If the original length L of the rubber band is 1 m, by how much (in m...
*December 3, 2010*

**chemistry**

thanks for the explanation!!!
*December 1, 2010*

**chemistry**

2. A 350 mL buffer solution containing 0.15 M HF and 0.150 M NaF is reacted with sodium hydroxide. What mass of NaOH can this buffer neutralize before the pH rises above 4.0? If the same volume of buffer was 0.35 M in HF and 0.35 M in NaF then what mass of NaOH could be ...
*December 1, 2010*

**chemistry**

For each of the following solutions, calculate the initial pH and the final pH after adding 0.010 mol of HCℓ. a) 500.0 mL of pure water i'm not sure how to do this question.. would the equation be h20+h30 equilibrium arrows h30+h20
*December 1, 2010*

**physics**

A 910 kg sports car slows down to 6.0 m/s to read a cross street sign. The 1440 kg pick-up truck following the sports car fails to see that the sports car has slowed and continues traveling at 17.0 m/s. The pick-up slams into the sports car. With what velocity will the two ...
*November 29, 2010*

**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*

**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**

of KCl
*October 1, 2010*

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