Saturday

February 28, 2015

February 28, 2015

Total # Posts: 554

**Chemistry**

yes, Al3+ sorry. so the moles=.01380. Could you help with the equation?
*January 9, 2012*

**Chemistry**

0.3724 g x 26.98MW = 10.05 mol -538.4kJ x 10.05 mol = -5410 kJ/mol 5410 kJ/mol of heat is evolved?????
*January 9, 2012*

**Chemistry**

The standard enthalpy of formation of Al3-(aq) is -538.4kJ/mol. How much heat is evolved when 0.3724 g of Al(s) reacts with excess hydrochloric acid?
*January 9, 2012*

**physical science**

Brad rides his bike 20 km. He covers the distance in 45 minutes (0.75 hours). What is his speed in kilometers per hour? A.44 km/hr B.15 km/hr C.9.0 km/hr D.27 km/hr
*December 18, 2011*

**Calculus**

find the second derivative of f(x)=3/(x^2+12)
*December 15, 2011*

**pre-algebra**

when rounding to the nearest cent does it have to be to right or left or does it matter?
*December 12, 2011*

**math**

Ryan takes 12 minutes to rake up and bag a pile of leaves. His sister Kareesa takes twice as long. How many minutes would it take both of them working together to complete 10 bags of leaves
*December 12, 2011*

**math**

What does a boy who likes to play with switches do?
*November 30, 2011*

**math**

12 tablespoons cause 16/4=4 so, 4x3=12!
*November 30, 2011*

**math **

sqrt(75)=sqrt(25)sqrt(3) which simplifies to 5 times sqrt(3) so 6x5xsqrt(3)= 30 sqrt(3)
*November 28, 2011*

**Calculus**

Given f"(x)=-25sin(5x)and f'(0)=0 and f(0)=4. Find f(pi/2)
*November 28, 2011*

**math**

30/40=.75 .75x100= 75 percent
*November 28, 2011*

**Physics**

A solid cylindrical disk has a radius of 0.18 m. It is mounted to an axle that is perpendicular to the circular end of the disk at its center. When a 40-N force is applied tangentially to the disk, perpendicular to the radius, the disk acquires an angular acceleration of 90 ...
*November 22, 2011*

**Geometry**

draw a picture, hint its more then 10 but less then 16
*November 16, 2011*

**Physics**

planet orbits a star once every 2.84 10^7 s in a nearly circular orbit of radius 1.42 10^11 m. (a) With respect to the star, determine the angular speed of the planet. (b) With respect to the star, determine the tangential speed of the planet. (c) With respect to the star, ...
*November 16, 2011*

**math**

3 feet in a yard 12 inches in a foot. 12x3x10=360 360/10=36 tiles
*November 16, 2011*

**geometry**

3 feet in a yard 12 inches in a foot. 12x3x10=360 360/10=36 tiles
*November 16, 2011*

**Algebra **

-9+3x=??? if you still need help let me know
*November 16, 2011*

**Algebra **

4-12x=??
*November 16, 2011*

**algebra**

-21+3x
*November 16, 2011*

**algebra **

27-2x
*November 16, 2011*

**algerbra**

ride=.40+.15x
*November 16, 2011*

**Physics**

Two children hang by their hands from the same tree branch. The branch is straight, and grows out from the tree trunk at an angle of 27.3° above the horizontal. One child, with a mass of 40.8 kg, is hanging 1.24 m along the branch from the tree trunk. The other child, with...
*November 16, 2011*

**SOCIAL STUDIES**

Harvard?
*November 16, 2011*

**Science**

A is wrong because they could have more or less children. C is wrong because it is impossible to have an aa child with the genotypes of the parents. And D is wrong because A is wrong. If you draw out the punett square you would see that B is correct
*November 16, 2011*

**Physics**

Disregard. I figured it out
*November 16, 2011*

**Physics**

The shaft of a pump starts from rest and has an angular acceleration of 3.40 rad/s2 for 11.0 s. (a) At the end of this interval, what is the shaft's angular speed? rad/s (b) What is the angle through which the shaft has turned
*November 16, 2011*

**physics**

A 220 N crate is pushed along the ground with a horizontal force. The coefficient of kinetic friction is 0.21 and the coefficient of static friction is 0.31. The crate moves at a constant speed of 4.1 m/s. a) Draw a free-body diagram for the crate. b) What is the size of the ...
*November 15, 2011*

**Algebra**

a^2+b^2=C^2 x^2+(x+1)^2=5^2 the other legs are 3ft and 4ft
*November 9, 2011*

**Algebra 1 (HELP PLEASE!!)**

5/3 x 3= 15/3 or 5 cups
*November 9, 2011*

**8th grade math**

it takes 5 minutes to make 2 cuts to give you 3 pieces. so if you continue at a rate of two cuts per 5 minute and in order to get 9 pieces you need 8 cuts. so I think 20 minutes
*November 9, 2011*

**Algebra 1**

Kim weighed 6.5lbs which is the same as 2/3t+3. so 6.5=3+2/3t 3.5=2/3t t=5.25
*November 9, 2011*

**science**

chloride is a form of chlorine
*November 9, 2011*

**science**

both
*November 9, 2011*

**physics**

I figured it out. the velocity of the recoil is in the negative direction.
*November 9, 2011*

**physics**

no that is not a problem. I just have to put in the number. the label is provided.
*November 9, 2011*

**physics**

The lead female character in the movie Diamonds Are Forever is standing at the edge of an offshore oil rig. As she fires a gun, she is driven back over the edge and into the sea. Suppose the mass of a bullet is 0.012 kg, and its velocity is +715 m/s. Her mass (including the ...
*November 9, 2011*

**physics**

Thanks. I was messing up the change in velocity part
*November 9, 2011*

**physics**

a baseball (m = 153 g) approaches a bat horizontally at a speed of 41.0 m/s (92 mi/h) and is hit straight back at a speed of 45.8 m/s (102 mi/h). If the ball is in contact with the bat for a time of 1.05 ms, what is the average force exerted on the ball by the bat? Neglect the...
*November 9, 2011*

**math**

bayside=5 lincoln x+1 hendricks=x band 20=5+x+x+1 20=2x+6 14=2x 7=x so hendricks has 7 and lincoln has 8
*November 9, 2011*

**Health, Safety, and Nutrition**

There are 9 calories in a gram of fat. 9x9=81 calories. 81/115=70.4%. C is the correct answer
*November 9, 2011*

**math algerba**

½(y-2)+2 =3/8(3y-4) Is 4 a solution?
*November 8, 2011*

**algebra 2**

49=x+(x+9)+(x+4) 49=3x+13 36=3x 12+x so one side is 12cm, on is 16cm and one is 21cm
*November 3, 2011*

**physics**

force=G(m1m2/r^2) G=6.673x10^-11
*November 3, 2011*

**Science**

work=force*distance work=800N*100m
*November 3, 2011*

**Math**

draw out the picture of the trapezoid. Since it is a regular trapezoid the bottom angles on both sides are the same. If you draw imaginary lines from the top to the bottom you can form a figure composed of two triangles and 1 square in the middle. You can then use some right ...
*November 3, 2011*

**Math**

a=P(1+(r/n))^nt
*November 3, 2011*

**Math**

semiannual means twice a year. so 2*5=10
*November 3, 2011*

**Algebra 1**

yes
*November 3, 2011*

**Basic math**

median is the middle number. so put the numbers in descending or ascending order and find the middle number. It would be 1,700
*November 3, 2011*

**SCIENCE**

They are "renewable" resources, and less polluting
*November 3, 2011*

**physics**

disregard. I figured it out
*November 3, 2011*

**physics**

A projectile of mass 0.550 kg is shot straight up with an initial speed of 22.0 m/s. (a) How high would it go if there were no air friction? I get 24.7m for this. (b)If the projectile rises to a maximum height of only 13.6 m, determine the magnitude of the average force due to...
*November 3, 2011*

**Math**

Yes you would multiply this. And assuming the tank is empty that is the correct answer
*November 3, 2011*

**physical science**

mechanical energy is the sum of kinetic and potential energy. there fore the one who says that there is mechanical energy is correct. Because there is potential energy present
*November 3, 2011*

**math**

a=Pe^rt a=25000e^(.0575)(7.5)
*November 2, 2011*

**math (calculus)**

A rectangular sheet of paper of width a and length b, where 0<a<b, is folded by taking one corner of the sheet and placing it at point P on the opposite long side of the sheet. The fold is flatened to form a crease across the sheet. Assuming that the fold is made that ...
*October 29, 2011*

**PHYSICS**

An object is originally moving at 13 m/s at the top of a frictionless, quarter-circular ramp with a radius of R = 13 meters. It then travels on a frictionless horizontal surface, around a frictionless loop of radius r = 2 meters, across another horizontal, frictionless surface...
*October 27, 2011*

**PHYSICS**

An object is thrown straight upwards from the ground at 28 m/s. Due to air resistance (a non-conservative force), the object loses 31.4 percent of its initial energy during its trip to reach maximum height. How much higher does the object travel if there was no air resistance...
*October 27, 2011*

**Physics**

A bicyclist is coasting straight down a hill at a constant speed. The mass of the rider and bicycle is 55.0 kg, and the hill is inclined at 16.0° with respect to the horizontal. Air resistance opposes the motion of the cyclist. Later, the bicyclist climbs the same hill at ...
*October 25, 2011*

**Probability**

0.062
*October 25, 2011*

**Spelling Skills**

Use the spelling words in the boxes below to complete the story. Then use proofreading marks to correct mistakes in the use of capital letters and periods.
*October 17, 2011*

**calculus**

A trough is 12 feet long and 3 feet across at the top. It ends are isosceles triangles with a height of 3 feet. If water is being pumped into the trough at 2.5 cubic feet per minute, how fast is the water level rising when the water is 1 foot deep?
*October 15, 2011*

**Chemistry**

How many grams of formaldehyde, H2CO, are in 500 ml of a 40% solution of formaldehyde in water? (Assume for this problem that the density of the formalin solution is 0.98 g/ml)
*September 19, 2011*

**chemistry**

How many grams of sodium were isolated from the decomposition of 0.0292 moles of Na2O, if the reaction occurred with a 44.9% percent yeild? 2 Na2O(s) --> 4 Na(s) + O2(g)
*September 13, 2011*

**chemistry**

How many molecules of NH3 could be generated from 64 molecules of N2 and 210 molecules of H2? How many molecules of N2 and H2 would be left over after the reaction?
*September 13, 2011*

**chemistry**

How many molecules of NH3 could be generated from 64 molecules of N2 and 210 molecules of H2? How many molecules of N2 and H2 would be left over after the reaction?
*September 13, 2011*

**Physics**

An object is in free fall. At one instant, it is traveling at 41 m/s. Exactly 3.2 s later, what is its speed? The acceleration of gravity is 9.8 m/s2 . Answer in units of m/s
*September 7, 2011*

**Science**

Hi, I am needing help with the following question. How long would it take to produce 150 kW with 780 J of energy? (make sure you have the corerct units)
*August 9, 2011*

**programming**

How do i read in a vector of integers with a space inbetween (i.e. 0 1 2 3) and make it an integer array? in java
*July 16, 2011*

**Physics**

A small ferryboat is 4.00 m wide and 6.00 m long. When a loaded truck pulls onto it, the boat sinks an additional 4.80 cm into the water. What is the weight of the truck?
*June 25, 2011*

**Spanish-8th gradePlease check**

1.¿Tienes que hacer mucha tarea hoy? Sí, tengo que hacer mucha tarea hoy. 2.¿Cómo vas al parque? Voy a pie. 3.¿Dónde está la cocina en tu casa? En mi casa, la cocina está abajo. 4.¿Prefieres lavar la ropa o quitar ...
*May 19, 2011*

**Physics**

Kathy is changing the tire of her car on a steep hill 20 m high. She trips and drops the 10 kg spare tire which rolls down the hill. What is the speed of the tire at the top of the next hill if the height of the hill is 5 m high?
*May 17, 2011*

**Physics**

A player kicks a footbal with a velocity of 27 m/s at an angle of 31° with the ground. How high does the ball travel?
*May 17, 2011*

**Chemistry**

When a sodium atom absorbs light at 330.2 nm, the 3s electron is promoted to the 4p level. How much energy would be required for ionization once the electron is in the 4p level?
*May 13, 2011*

**Chemistry**

When a sodium atom absorbs light at 330.2 nm, the 3s electron is promoted to the 4p level. How much energy would be required for ionization once the electron is in the 4p level?
*May 13, 2011*

**chemistry**

Thanks, How many atoms are in a body-centered cubic unit cell??? a- one b- two c- four d- six e- eight
*May 4, 2011*

**Chem**

How many grams of O2 are required to burn13.0g of acetylene? The answer I got is 40gO2 is this right.
*April 25, 2011*

**chem.**

How many grams of CO2 and grams of H2O are produced when 13.0g C2H2?
*April 25, 2011*

**chemistry**

How many grams of O2 are required to burn 13.0g of acetylene?
*April 25, 2011*

**US History**

How did the US become involved in the politics of Southeast Asia?
*April 24, 2011*

**History**

What did Kennedy hope to accomplish with the New Frontier?
*April 23, 2011*

**Personal Finance**

Mike Welch purchased 5,000 shares of Grass Roots stock for $82 per share and paid a commission of 1% on the purchase price. The current value of the stock is $96 per share. Mike received no dividends last year.
*April 21, 2011*

**physics**

1. A sound is made by a speaker, which then radiates in all directions. The sound wave is described by A(r) sin(2r - 600t) where the distances are in meters, and the time in seconds. The A(r) just indicates that the amplitude has some distance dependence--it decreases smoothly...
*April 17, 2011*

**science**

A 250 kg object is acceelerating at 2.8 m/s2. What force was required to achieve this?
*April 6, 2011*

**Alegbra 2**

how do i find out what the amplitude, period, h, k and midline of problems 1) y= sin (x-5)=7 2) y=3 cos (x- pie) -1 3) y= Sin3x+4 4) y= 1/2 cos 2x-2
*March 20, 2011*

**Physics**

A 3 Kg lead ball is dropped into a 3 L insulated pail of water initially at 20.0 degrees C. If the final temperature of the water-lead combination is 25 degress C, what was the initial temperature of the lead ball?
*March 19, 2011*

**Chemistry**

A cubic piece of metal measures 7.50 cm on each edge. If the metal is nickel, whose density is 8.90g/cm^3, what is the mass of the cube?
*March 1, 2011*

**Physics**

A class of 11 students taking an exam has a power output per student of 124 W. Assume that the initial temperature of the room is 18.7°C and that its dimensions are 6.00 m by 14.5 m by 3.40 m. What is the temperature (in °C, do not enter units) of the room at the end ...
*February 9, 2011*

**VHS**

a triangle has sides with lengths of 11 meters, 9 meters, and 7 meters. what type of triangle is it?
*February 5, 2011*

**Controls**

If you have a tank of water at sea level and the temperature of the water in the tank is 110 degrees F, what is the height of the water if the pressure at the bottom of the tank is 95 inches of mercury(absolute)
*January 31, 2011*

**Chemistry**

The reaction of fluorine with ammonia produces dinitrogen tetrafluoride and hydrogen fluoride. 5 F2(g) + 2 NH3(g) N2F4(g) + 6 HF(g) (a) If you have 73.7 g NH3, how many grams of F2 are required for complete reaction? b) How many grams of NH3, are required to produce 5.25 g HF...
*January 27, 2011*

**Social Studies**

i donno
*January 18, 2011*

**Math**

To win one million dollars, you must draw two cards whose sum is nine, from a stack of cards numbered through 10. After the first draw you replace the card and shuffle the stack again for the the second draw. What is the chance that your two cards will have a sum of nine.?
*January 11, 2011*

**physics**

The blades of a fan running at low speed turn at 200 rpm. When the fan is switched to high speed, the rotation rate increases uniformly to 340 rpm in 5.92 s. How many revolutions do the blades go through while the fan is accelerating?
*December 11, 2010*

**Physics**

The blades of a fan running at low speed turn at 200 rpm. When the fan is switched to high speed, the rotation rate increases uniformly to 340 rpm in 5.92 s. (a) What is the magnitude of the angular acceleration of the blades? (b) How many revolutions do the blades go through ...
*December 11, 2010*

**Physics**

A 15500 N automobile travels at a speed of 41 km/h northward along a street, and a 7000 N sports car travels at a speed of 65 km/h eastward along an intersecting street. a)If neither driver brakes and the cars collide at the intersection and lock bumpers, what will the ...
*December 11, 2010*

**college math**

Express (cos^2t/tan^2t) as an expression that involves only the sine function.
*December 11, 2010*

**Science-Chemistry**

Calculate the number of grams of carbon dioxide that can be absorbed by a complete reaction with a solution that contains 5.00 grams of sodium hydroxide
*December 2, 2010*

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