Thursday

October 23, 2014

October 23, 2014

Number of results: 51,694

**Physics**

The instruments attached to a weather balloon have a mass of 5.2 kg. The balloon is released and exerts an upward force of 98 n on the instruments. A)what is the acceleration of the balloon and instruments? B) after the balloon has accelerated for 10s, the instruments are ...
*January 12, 2013 by Jules*

**physics12**

The instruments attached to a weather balloon have a mass of 5.1 kg. (a) The balloon is released and exerts an upward force of 102 N on the instruments. What is the acceleration of the balloon and instruments? (b) After the balloon has accelerated for 13 seconds, the ...
*December 11, 2011 by Hannah*

**physics**

the instruments attached to a weather balloon have a mass of 5.0 kg. the balloon is released and exerts an upward force of 98 N on the instruments. (a) what is the acceleration of the balloon and instruments? (answer is 9.8 m/s^2.. just dont know how to get there..) (b)after ...
*October 10, 2011 by tayler*

**physics**

the instruments attached to a weather balloon have a mass of 5.0 kg. the balloon is released and exerts an upward force of 98 N on the instruments. (a) what is the acceleration of the balloon and instruments? (answer is 9.8 m/s^2.. just dont know how to get there..) (b)after ...
*October 10, 2011 by tayler*

**Physics**

A spherical hydrogen-filled balloon is used to lift a load of 5950 N (in addition to the weight of the hydrogen). Suppose the density of the air is 1.18 kg/m3. Find the minimum necessary radius for the balloon
*April 3, 2014 by Jason*

**physics**

An empty rubber balloon has a mass of 0.0100 kg. The balloon is filled with helium at a density of 0.181 kg/m3. At this density the balloon is spherical with a radius of 0.300 m. If the filled balloon is fastened to a vertical line, what is the tension in the line?
*December 20, 2010 by april*

**physics**

The instruments attached to a weather balloon in the figure below have a mass(m) of 5.0 kg. The balloon is released and exerts an upward force(F) of 92 N on the instruments.
*November 2, 2010 by eden*

**Physics**

I found the first three parts of the question but I can't figure out part d. The instruments attached to a weather balloon in the figure below have a mass(m) of 5.5 kg. The balloon is released and exerts an upward force(F) of 109 N on the instruments. (a) What is the ...
*January 3, 2010 by Sasha*

**physics**

an empty rubber balloon has mass 0.0120kg, the balloon is filled with helium of density 0.181 kg/m^3. the balloon is spherical w/ radius 0.500m. if the balloon is ties to a vertical string, what is thw tension in the string? density of air 1.29 kg/m^3
*December 15, 2012 by Helen*

**AP Chemistry**

The buoyant force on a balloon is equal to the mass of air it displaces. The gravitational force on the balloon is equal to the sum of the masses of the balloon, the gas it contains, and the balloonist. If the balloon and balloonist together weight 175 kg, what would the ...
*October 11, 2010 by Emma*

**physics**

A spherical balloon has a radius of 6.76 m and is filled with helium. How large a cargo can it lift, assuming that the skin and structure of the balloon have a mass of 950 kg? Neglect the buoyant force on the cargo volume itself.
*April 18, 2010 by Anonymous*

**Chemistry**

The buoyant force on a balloon is equal to the mass of air it displaces. The gravitational force on the balloon is equal to the sum of the masses of the balloon, the gas it contains, and the balloonist. If the balloon and balloonist together weight 175 kg, what would the ...
*October 11, 2010 by Emma*

**AP Chemistry**

The buoyant force on a balloon is equal to the mass of air it displaces. The gravitational force on the balloon is equal to the sum of the masses of the balloon, the gas it contains, and the balloonist. If the balloon and balloonist together weight 175 kg, what would the ...
*October 12, 2010 by Em*

**Physics**

An empty rubber balloon has a mass of 0.012kg. the balloon is filled with helium at 0 degrees celcius, 1 atm pressure, and a density of 0.179 kg/m3. the filled balloon has a radius of 0.5 m. a)what is the magnitude of the buoyant force acting on the balloon? b)what is the ...
*March 4, 2010 by Taylor*

**Physics**

A 1.8-g balloon is filled with helium gas. When a mass of 4.8 g is attached to the balloon, the combined mass hangs in static equilibrium in midair. Assuming that the balloon is spherical, what is its diameter? (The density of helium is 0.179 kg/m3, and the density of air is 1...
*November 7, 2011 by mymi*

**Physics**

A balloon with a mass of 90 kg is filled with helium (density = 0.179 kg/m3). The balloon is spherical and has a diameter of 11.0 m. What is the maximum mass that can be attached to the bottom of this this helium balloon, for it to be able to fly? The density of air is 1.29 kg...
*January 17, 2013 by Alphonse*

**physics**

A large balloon of mass 237 kg is filled with helium gas until its volume is 318 m3. Assume the density of air is 1.29 kg/m3 and the density of helium is 0.179 kg/m3. (b) Calculate the buoyant force acting on the balloon.________N (c) Find the net force on the balloon and ...
*November 7, 2012 by Amanda*

**PHYSICS**

A large balloon of mass 237 kg is filled with helium gas until its volume is 318 m3. Assume the density of air is 1.29 kg/m3 and the density of helium is 0.179 kg/m3. (b) Calculate the buoyant force acting on the balloon. ________N (c) Find the net force on the balloon and ...
*November 8, 2012 by Amy*

**chem**

In 1897 the Swedish explorer Andree tried to reach the North Pole in a balloon. The balloon was filled with hydrogen gas. The hydrogen gas was prepared from iron splints and diluted sulfuric acid. The reaction is given below. Fe(s) + H2SO4(aq) FeSO4(aq) + H2(g) The volume of ...
*November 16, 2007 by mel*

**Chemistry**

The total mass that can be lifted by a balloon is given by the difference between the mass of air displaced by the balloon and the mass of the gas inside the balloon. Consider a hot air balloon that approximates a sphere 5.00 m in diameter and contains air heated to 65 C. The ...
*December 14, 2012 by Savannah*

**Chemistry**

The total mass that can be lifted by a balloon is given by the difference between the mass of air displaced by the balloon and the mass of the gas inside the balloon. Consider a hot air balloon that approximates a sphere 5.00 m in diameter and contains air heated to 65 C. The ...
*December 16, 2012 by Savannah*

**PHYSICS PLEASE HELP**

A large balloon of mass 237 kg is filled with helium gas until its volume is 318 m3. Assume the density of air is 1.29 kg/m3 and the density of helium is 0.179 kg/m3. (b) Calculate the buoyant force acting on the balloon. ____________N (c) Find the net force on the balloon and...
*November 8, 2012 by AMY*

**Calculus**

t: 0 2 5 7 11 12 r'(t): 5.7 4.0 2.0 1.2 0.6 0.5 The volume of a spherical hot air balloon expands as the air inside the balloon is heated. The radius of the balloon in feet is modeled by a twice-differentiable function of r of time t, where t is measured in minutes. For 0<t...
*November 25, 2008 by Craig*

**calculus**

a spherical balloon filled with gas has a leak that permits the gas to escape at a rate of 1.5 cubic meters per minute. how fast is the surface area of the balloon shrinking when the radius is 4 meters?
*November 7, 2013 by james*

**AP calculus AB**

A spherical balloon is being filled with air in such a way that its radius is increasing at a rate of 2 centimeters per second. At what rate is the volume of the balloon changing at the instant when its surface has an area of 4 pi square centimeters.
*December 29, 2010 by jennifer*

**help on calculus**

A spherical balloon is being filled with air in such a way that its radius is increasing at a rate of 2 centimeters per second. At what rate is the volume of the balloon changing at the instant when its surface has an area of 4 pi or 12.56637061 square centimeters?
*December 30, 2010 by winston*

**related rates problem-calculus**

A spherical balloon is being filled with air in such a way that its radius is increasing at a rate of 2 centimeters per second. At what rate is the volume of the balloon changing at the instant when its surface has an area of 4 pi square centimeters?
*December 30, 2010 by james*

**science**

You are a maker of hot air balloons and wish to construct a balloon that will lift you and a friend to places unknown. Your standard balloon design is a perfectly spherical, nylon fabric balloon with a small hole on the bottom for the burner that heats the air. Nylon starts to...
*April 11, 2013 by Sahil*

**Physics :(( help please TT**

You are a maker of hot air balloons and wish to construct a balloon that will lift you and a friend to places unknown. Your standard balloon design is a perfectly spherical, nylon fabric balloon with a small hole on the bottom for the burner that heats the air. Nylon starts to...
*April 12, 2013 by Ian*

**calculus**

air is being pumped into a spherical balloon at a rate of 8 cm^3/min. Find the rate at which the radius of the balloon is increasing when the balloon's radius is 5 cm.
*April 8, 2013 by marisol*

**science**

A weather balloon carries instruments that measure temperature, pressure, and humidity as it rises through the atmosphere. Suppose such a balloon has a volume of 1.2 m^3 at sea level where the pressure is 1 atm and the temperature is 20°C. When the balloon is at an altitude of...
*November 19, 2011 by Shirley*

**math**

a spherical balloon with radius r inches has volume V9r) =(4/3)πr^3. Find a function that represents the amount of air required to inflate the balloon from a radius of r inches to a radius of r+1 inches
*September 12, 2010 by Sasha*

**Calculus**

A spherical balloon with a radius "r" inches has volume V(r)=(4/3)(pi)(r^3). Find the function that represents the amount of air required to inflate the balloon from a radius of "r" inches to a radius of r+1 inches.
*September 22, 2007 by Raj*

**math**

A spherical balloon with radius r inches has volume V (r) = 4 3 r3 . Find the function f(r) that represents the amount of air required to inflate the balloon from a radius of r inches to a radius of r + 2 inches.
*May 5, 2011 by Renaldo Nguyen*

**Calculus**

A spherical balloon with a radius r inches has volume V(r)= 4/3 Pi r^3. Find a function that represents the amount of air required to inflate the balloon from a radius of r inches to a radius of r+1 inches. An explanation would be appreciated, as I have no clue how to even begin.
*September 11, 2010 by Chelsea*

**physical science**

A Weather balloon carries instruments that measure temperature, pressure, and humidity as it rises through the atmosphere. Suppose such a balloon has a volume of 1.2 m3 at sea level where the pressure is 1 atm and the temperature is 20oC. When the balloon is at an altitude of ...
*October 4, 2012 by maria*

**math**

a boy is blowing a spherical balloon at a rate of 50 cm3/s.at what rate is the radius of the balloon changing when the radius is 10 cm?give your answer to 2 decimal places.
*October 11, 2011 by jj*

**math**

a boy is blowing a spherical balloon at a rate of 50 cm3/s.at what rate is the radius of the balloon changing when the radius is 10 cm?give your answer to 2 decimal places.
*October 11, 2011 by jj*

**Calculus**

a spherical balloon is inflated with gas at the rate of 500 cubic centimeters per minute. how fast is the radius of the balloon increasing at the instant the radius is 30 centimeters?
*November 1, 2009 by Anonymous*

**calculus**

A spherical balloon is leaking air at 2 cubic inches per hour. How fast is the balloon's radius changing when the radius is 2 inches.
*January 9, 2012 by Jordan*

**Physics**

A spherical helium filled balloon is attached to a string that is fixed to the ground. the balloon has a volume of .30/4m^3 and helium has a density of .20 kg/m^3. What is the weight of the balloon and helium if the tension on the string is .8N?
*October 11, 2013 by George*

**Chemistry**

.Question part Points Submissions 1 0/0.5 2/3 Total 0/0.5 ...In the explosion of a hydrogen-filled balloon, 0.75 g of hydrogen reacted with 6.9 g of oxygen to form how many grams of water vapor? (Water vapor is the only product.) i already posted this but i dont think people ...
*September 11, 2010 by Rebekah*

**physics**

a weather balloon carries instruments that measure temperature,pressure and humidity as it rises through the atmosphere.Suppose such a balloon has a volume of 1.2 m^3 at sea level where the pressure is 1 atm and the temperature is 20 degree Celsius.When the balloon is at an ...
*November 1, 2011 by jennaq*

**Physics**

A spherical helium filled balloon is attached to a string that is fixed to the ground. the balloon has a volume of .30/4m^3 and helium has a density of .20 kg/m^3. What is the weight of the balloon and helium if the tension on the string is .8N? What is the Gravitational force...
*October 11, 2013 by George*

**Physics**

A spherical helium filled balloon is attached to a string that is fixed to the ground. the balloon has a volume of .30/4m^3 and helium has a density of .20 kg/m^3. What is the weight of the balloon and helium if the tension on the string is .8N? What is the Gravitational force...
*October 11, 2013 by George*

**calc**

im so confused :( Willie Makit blows up a spherical balloon. He recalls that the volume is V=4/3Pi*r^3. In order for the radius to increase at 2cm/sec, how fast must Willie blow air into the balloon when the radius is 3 cm?
*December 29, 2010 by me*

**Physics**

A balloon of negligible mass is filled with helium gas (p=0.179 kg/m^3) until its volume is just large enough to lift a 25.0 kg load. (a) Find this volume. (b) Find the buoyant force exerted by air (p=1.29 kg/m^3) on the balloon.
*April 24, 2013 by Lashawn*

**math**

Air is pumped into a balloon such that its volume increases at the rate of 75cm^3 per second. It is assumed that the balloon is spherical all the time. Find in term of pi the rate at which the radius of teh balloon is increasing when the radius is 5cm. Given the balloon was ...
*March 27, 2014 by rosa*

**math- Calc**

a spherical balloon is filled with water. if the water is leaking out at a rate of 2 cm^3/min, find the rate at which the radius is changing when the volume is v=1000cm^3?
*April 22, 2014 by Louis*

**calculus**

A spherical balloon is being inflated at a rate of 10 cubic inches per second. How fast is the radius of the balloon increasing when the surface area of the balloon is square inches? Enter your answer correct to 3 decimal places.
*March 25, 2011 by Anonymous*

**Calculus**

A spherical balloon is being inflated at a rate of 10 cubic inches per second. How fast is the radius of the balloon increasing when the surface area of the balloon is 2pi square inches? Enter your answer correct to 3 decimal places.
*March 28, 2011 by Anonymous*

**Physics**

What minimum sized balloon would you have to fill in order to be able to be lifted into the air? Take your mass to be 100 kilograms and the temperature of the outside air to be 20 degrees C. Neglect the mass of the balloon rubber and basket and assume that the balloon is ...
*March 15, 2013 by steve*

**College Math**

A spherical balloon has a radius of 9 centimeters. Find the amount of air required to fill the balloon. Round to the nearest hundredth
*March 26, 2012 by Rochelle Finister*

**Chemistry**

need to know how to solve the following.... a gas filled weather balloon floating in the atomsphere has an initial volume of 850 L. The balloon rises to a region where the pressure is 56 kPa and its volume expands to 1700 L. If the temperature remains the same, what was the ...
*September 6, 2011 by remraf*

**Calculus**

Air is being pumped into a spherical balloon and the volume is increasing at the rate of 100 cubic cm per minute. How fast is the radius of the balloon increasing when the radius is 10 cm? (V=4/3 times pie times r^3)
*October 15, 2012 by Anonymous*

**calc**

hydrogen is being pumped into a spherical balloon at the rate of 250 cubic inches per minute. in a and b, you must provide an equation with their proper numerical factors when showing the relationships inquired A) write an equation showing the relationship between the rates at...
*November 15, 2007 by beckii*

**math**

A design on a balloon is 6 cm wide when the balloon holds 44 cm to the third power of air. How much must the balloon hold for the design to be 24 cm wide? Since the "width" increases by a factor of 4, the volume will increase by a factor of 4^3 = 64, even if the balloon is not...
*November 25, 2006 by Susie*

**physics**

A lost shipping container is found resting on the ocean floor and completely submerged. The container is 5.7 m long, 2.7 m wide, and 2.3 m high. Salvage experts attach a spherical balloon to the top of the container and inflate it with air pumped down from the surface. When ...
*March 10, 2013 by chel*

**Physics**

A lost shipping container is found resting on the ocean floor and completely submerged. The container is 6.0 m long, 2.2 m wide, and 2.3 m high. Salvage experts attach a spherical balloon to the top of the container and inflate it with air pumped down from the surface. When ...
*April 19, 2014 by Linda*

**Physics**

In this problem, your task is to analyze a lead balloon. The balloon in question is a hollow sphere of diameter of 20.0 m, constructed from a lead foil 0.25 mm thick and filled with helium gas. Below the balloon, a passenger basket is suspended. The mass of the passenger ...
*June 15, 2012 by Rob*

**calculus**

Air is being pumped into a spherical balloon so that its volume increases at a rate of 80cm^3/s. How fast is the surface area of the balloon increasing when its radius is 7cm?
*October 29, 2009 by Ash*

**Chemistry**

You have two gas-filled balloons, one containing He and the other containing H2. The H2 balloon is twice the size of the He balloon. The pressure of gas in the H2 balloon is 1 atm, and that in the He balloon is 2 atm. The H2 balloon is outside in the snow (−5 °C), and ...
*March 30, 2007 by Luis*

**Calculus**

A spherical balloon is inflated at a rate of 10 cubic feet per minute. How fast is the radius of the balloon changing at the instant the radius is 4 feet? And The radius of a circle is decreasing at a rate of 2 ft/minute. Find the rate at which the area is decreasing with ...
*August 26, 2011 by Branden*

**Math**

A spherical balloon expands when it is taken from the cold outdoors into a warm house. If the surface area increases by 50% (factor of 1.50), by what percentage does the radius of the balloon change? a)7.7% b)50% c)100% d)75% e)22%
*September 8, 2010 by Johnny*

**Math**

A spherical balloon with a surface area of 36pi square inches is inflated further until its diameter has increased by 50%. The surface area of the balloon is now? I know the formula for surface area is A=4pi*r squared. I don't understand how you can figure the problem without ...
*May 11, 2014 by Gayle*

**chem**

In the explosion of a hydrogen-filled balloon, 0.54 g of hydrogen reacted with 6.6 g of oxygen to form how many grams of water vapor?
*October 4, 2010 by jeff*

**Physics PLEASE help!**

I REALLY NEED HELP WITH THIS!!!!! In this problem, your task is to analyze a lead balloon. The balloon in question is a hollow sphere of diameter of 20.0 m, constructed from a lead foil 0.25 mm thick and filled with helium gas. Below the balloon, a passenger basket is ...
*June 16, 2012 by Eric*

**Calculus**

Air is being pumped into a spherical balloon so that its volume increases at a rate of 30 cubic centimeters per second. How fast is the surface area of the balloon increasing when its radius is 19 cm? V= 4/3*pi*r^3 S= 4 pi r^2
*September 24, 2009 by Z32*

**calculus**

Air is being pumped into a spherical balloon so that its volume increases at a rate of 80 cubic centimeters per second. How fast is the surface area of the balloon increasing when its radius is 8 cm?
*February 25, 2010 by idk*

**Calc**

Air is being pumped into a spherical balloon so that its volume increases at a rate of 90{cm}^3/s. How fast is the surface area of the balloon increasing when its radius is 7{cm}? Recall that a ball of radius r has volume \displaystyle V={4}/{3}pie r^3 and surface area S=4\pi r^2
*March 15, 2009 by Vince*

**physics**

Suppose that a party balloon is spherical, has a radius of 16 centimetres and is filled with helium. Furthermore suppose that we do our experiment under standard atmospheric conditions, when the air density is \(\rho = 1.225 kg/m^3\). How many of these balloons should a 75 ...
*March 26, 2014 by Nick*

**Chemistry **

You have two gas-filled balloons, one containing He and the other H2. The H2 balloon is twice the size of the He balloon (let the He balloon have a volume of 1 -L and the H2 balloon. a volume of 2 L). The pressure of gas in the H2 balloon is 1 atm while that in the He balloon ...
*February 19, 2012 by Bria*

**physics**

How big would a spherical helium balloon have to be to lift a 70kg person? The mass of the balloon's skin is 4.0kg
*November 19, 2013 by sandra*

**physics**

What is the density of air filled balloon and the mass of 6 inch balloon air filled
*March 25, 2011 by ami*

**physics**

What is the density of air filled balloon and the mass of 6 inch balloon air filled
*March 25, 2011 by ami*

**Calculus**

Air is being pumped into a spherical balloon so that its volume increases at a rate of 80 cm^3 per second. How fast is the surface area of the balloon increasing when its radius is 9cm? * ball of radius r has volume V=(4/3)pi r^3 and surface area S=4pir^2 ** I try to do it ...
*October 25, 2012 by Susanna*

**Math**

A spherical balloon is being inflated. Estimate the rate at which its surface area is changing with respect to the radius when the radius measures 20 cm.
*September 22, 2013 by Lala*

**chemistry**

Balloon X is filled with the carbon monoxide. Balloon Y is filled to the same volume with carbon dioxide. The balloons are left for several days in a room at constant temperature. Which balloon would you expect to be smallest after this period of time?
*April 1, 2011 by Morgan*

**General Chemistry**

A balloon is filled with helium gas at 23 degrees C. The balloon expands until the pressure is equal to the atmospheric pressure of 755 toor. The balloon rises to an altitude of 6000 feet where the pressure is 550 toor and the temperature is 5 degrees C. Calculate the percent ...
*September 4, 2011 by Ronnica*

**Physics**

A disk and a hollow spherical shell, like a basketball, are released at the same time at the top of an inclined plane. The spherical shell has a mass M and a radius R; the disk has a mass 2M and a radius 2R. If the two objects are released at rest, and the height of the ramp ...
*November 24, 2010 by Ree*

**Math**

A spherical balloon is inflated with helium at the rate of 100pi ft ^3/min. How fast is the ballon's radius increasing at the instant the radius is 5ft.?
*November 30, 2012 by Peggy*

**Physics**

A weather balloon is floating at a constant height above Earth when it releases a pack of instruments. If the pack hits the ground with a velocity of -68.5 m/s, how far does the pack fall? a = -9.80 m/s^2 Vf = -68.5 m/s d = ?
*September 4, 2007 by Anon*

**Physics**

I NEED HELP! Already answered on here but does not make sense/work. Please HELP! A 2.7 kg balloon is filled with helium ( density = 0.179 kg/m^3). If the balloon is a sphere with a radius of 5.2m , what is the maximum weight it can lift?
*December 1, 2010 by Kristy*

**AP Physics**

a weather station releases a weather balloon.The balloon's buoyancy accelerates it upward at 15m/s sq.At the same time,a wind accelerates it horizontally to the right at 6.5m/s sq.What is the resulting acceleration
*September 26, 2014 by ren*

**Chem**

A scuba diver creates a spherical bubble with a radius of 4.0 at a depth of 30.0 where the total pressure (including atmospheric pressure) is 4.00 . What is the radius of the bubble when it reaches the surface of the water? (Assume atmospheric pressure to be 1.00 and the ...
*November 20, 2010 by Jess*

**Calculus**

A spherical party balloon is being inflated with helium pumped in at a rate of 12 cubic feet per minute. How fast is the radius growing at the instant when the radius has reached 1 ft?
*December 17, 2012 by Anonymous*

**Physics**

Hey can someone help me out? I only have 1 attempt left on this question and do not understand it at all!!! A 3.5 kg balloon is filled with helium ( density = 0.179 kg/m^3). If the balloon is a sphere with a radius of 5.2m , what is the maximum weight it can lift?
*December 3, 2009 by Tommy*

**Physics gravity**

A thin spherical shell has a radius of 2.4 m and a mass of 410 kg, and its center is located at the origin of a coordinate system. Another spherical shell with a radius of 1 m and mass 135 kg is inside the larger shell with its center at 0.6 m on the x axis. What is the ...
*April 8, 2013 by Chel*

**Chemistry**

A scuba diver creates a spherical bubble with a radius of 4.0cm at a depth of 30.0m where the total pressure (including atmospheric pressure) is 4.00 atm. What is the radius of the bubble when it reaches the surface of the water? (Assume atmospheric pressure to be 1.00atm and ...
*November 20, 2010 by Jess*

**math-calculus**

A spherical party balloon is being inflated with helium pumped in at a rate of 12 cubic feet per minute. How fast is the radius growing at the instant when the radius has reached 1 ft?
*December 17, 2012 by Mel*

**physics**

If you live in a city your stove can be powered by natural gas. This gas is mainly methane gas and has a density of about 0.72 kilograms per cubic meter. What minimum sized balloon would you have to fill in order to be able to be lifted into the air? Take your mass to be 75 ...
*March 14, 2012 by dale*

**chemistry**

If you filled up three balloons with equal volumes of hydrogen, argon, and carbon dioxide gas all at the same temperature and pressure, which balloon would weigh the most? which balloon would weigh the least?
*April 22, 2012 by akboyer31*

**Calculus**

A spherical ball is being filled with air. When the radius r=9cm, the radius is increasing at a rate 4 cm/s. How fast is the volume changing at this time (leave your answer approximate)?
*November 12, 2012 by Jax*

**math**

A spherical ball is being filled with air. When the radius r=7cm, the radius is increasing at a rate 2 cm/s. How fast is the volume changing at this time (leave your answer approximate)?
*November 12, 2012 by Rav*

**CHEMISTRY**

the hindenburg was a hydrogen -filled dirigiable that exploded on 1937. The Hindenburg held 6.5*10^5 L of hydrogen gas at 23C and 760mmHg, what mass of hydrogen (H2) was present? calculate n in PV=nRT mass=n*molmassH2
*January 9, 2007 by TIFFANY*

**physics**

A mountain-climber friend with a mass of 82 kg ponders the idea of attaching a helium-filled balloon to himself to effectively reduce his weight by 25% when he climbs. He wonders what the approximate size of such a balloon would be. Hearing of your physics skills, he asks you...
*March 28, 2012 by Kristie*

**physics**

A mountain-climber friend with a mass of 82 kg ponders the idea of attaching a helium-filled balloon to himself to effectively reduce his weight by 25% when he climbs. He wonders what the approximate size of such a balloon would be. Hearing of your physics skills, he asks you...
*March 29, 2012 by Jim*

**physics**

A mountain-climber friend with a mass of 82 kg ponders the idea of attaching a helium-filled balloon to himself to effectively reduce his weight by 25% when he climbs. He wonders what the approximate size of such a balloon would be. Hearing of your physics skills, he asks you...
*April 1, 2012 by christy*

**SCIENCE**

CREATE ONE OF THE FOLLOWING WEATHER INSTRUMENTS:THERMOMETER,BAROMETER,ANEMOMETER,WEATHER VANE,OR RAIN GAUGE.
*October 3, 2012 by Lakshmi*

**Jr. High Pressure Challenge Question**

A small flask has a mass of 22.71 g. When it is filled with water the total mass is 153.38 g. When it is filled with milk the total mass is 157.67 g. What is the density of milk?
*December 26, 2010 by Anonymous*

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