Saturday

May 23, 2015

May 23, 2015

Total # Posts: 2,957

**Physics **

A girl of mass 55 kg throws a ball of mass 0.8 kg against a wall. The ball strikes the wall horizontally with a speed of 25 m/s, and it bounces back with the same speed. The ball is in contact with the wall 0.05 s. What is the average force exerted on the wall by the ball? A) ...
*March 30, 2012*

**Biology**

do all specific proteins have the same function in different living organisms?
*March 28, 2012*

**chemistry**

given the equilibrium constant for the following reaction at 500 K, 2 NO (g) + O2 (g) <==> 2 NO2 (g) Kc = 6.2x10^5 calculate the equilibrium constant for the reaction expressed as partial pressures, Kp. the answer is 1.51x10^4. How do i get this?
*March 28, 2012*

**chemistry**

Why do the concentrations of Pb 2+ and SO4 2- ions in a saturated solution of PbSO4 in contact with solid PbSO4 remain the same when the solution evaporates to half of its original volume? it has to do with equilibrium.
*March 28, 2012*

**chemistry**

For the gaseous equilibrium represented below, it is observed that greater amounts of PCl3 and Cl2 are produced as the temperature is increased. PCl5 (g) <==> PCl3 (g) + Cl2 (g) a) what is the sign of delta S for the reaction? Provide a legitimate rationale for the ...
*March 28, 2012*

**ap chemistry**

When 50.0 mL of a 0.010 M CuNO3 solution is mixed with 150.0 mL of a 0.010 M NaCl solution, a precipitate forms (Ksp = 1.9 x 10^-7). a) Determine all final ion concentrations b) Determine the mass of the precipitate formed. How do i do this?
*March 28, 2012*

**Math**

Suppose that 600 meters of fencing are used to enclose a corral in the shape of a rectangle on three sides, and then a semicircle on the fourth side (The diameter of the semicircle is equal to the width of the rectangle). Find the dimensions of the corral with maximum area.
*March 28, 2012*

**math**

Sorry. n=3/2 or 1.5
*March 28, 2012*

**math**

n= 2/3
*March 28, 2012*

**math **

2/3 x n = 4/9
*March 28, 2012*

**Physics**

An indestructible bullet 1.85 cm long is fired straight through a board that is 11.5 cm thick. The bullet strikes the board with a speed of 400 m/s and emerges with a speed of 285 m/s. (a) What is the average acceleration of the bullet as it passes through the board? Give your...
*March 28, 2012*

**Physics**

Find the angular velocity of a clock's second hand and the linear speed and linear acceleration of a point on the second hand 1.96 cm from the rotation axis.
*March 26, 2012*

**Physics**

Find the angular velocity of a clock's second hand and the linear speed and linear acceleration of a point on the second hand 1.96 cm from the rotation axis.
*March 26, 2012*

**math**

1/2 x 2/3
*March 26, 2012*

**Physics**

2700
*March 25, 2012*

**Integrals/Related Rates(?)/Volume**

Fluid is flowing in a tube that has a radius of 3 centimeters. Water is flowing through a circular cross section at a rate of (9-r^2) cm/s, where r is the distance from the center of the cross section. What is the total amount of water that flows through the cross section in 4...
*March 22, 2012*

**Math**

First, make sure to convert all of your units to meters. Then, sum the sides (so 2*1.4*1.5, two because there are two of the same side, and then do the same for the other two types of sides.
*March 22, 2012*

**Chemistry**

the reaction 2 NO + O2 <=> 2 NO2 (delta H = -114.2 kJ) has a Kc=7.00 x 10^7 at 200 degrees Celsius. what is the value of Kc at 400 degrees celsius? a. 1.25x10^4 b. 1.68x10^8 c.3.91x10^11 d. 5.74x10^22 e. answer not given
*March 20, 2012*

**Chemistry**

what is the solubility in mol/L of insoluble Ca3(PO4)2 (Ksp=1.00x10^-26)in a solution containing .00100 M Na3PO4? a. 2.15x10^-7 b. 7.18x10^-8 c. 7.18x10^-9 d. 1.00x10^-23 e. answer not given
*March 20, 2012*

**humanities**

for my homework my teacher has set me whats the meaning of a human honey pot and i cant find any good websites so i was wondering if you new any
*March 18, 2012*

**Physics**

If a lever is 6 feet long and the fulcrum is six inches from a 500 N boulder, how many newtons of force would be needed to life the boulder?
*March 17, 2012*

**Physics**

all I know is that it's not simply n(wavelength)=dsin(theta) because I plugged the numbers in and they were wrong. (n=1)
*March 17, 2012*

**Physics**

Suppose that a 14-m tall platform has a ramp that is 98 m long. If a box needs 245 N of force of lift it, how many N of force is required to push it up the ramp?
*March 16, 2012*

**Algebra 1**

Factor completely 4x^3+x^2y-36x-9y
*March 15, 2012*

**geometry**

Thank You!! Is there any way you can explain a little bit to me how this answer is found? Thank You soo much for your help it is very greatly appreaciated!!
*March 14, 2012*

**geometry**

Robert is making a scale drawing of a painting that is 48in. wide by 120in. high. His paper is 12in. wide and 24in. tall. He decides to use the scale 1in.= 4in. Is this a reasonable scale?
*March 14, 2012*

**3rd grade math**

What is the difference between the perimeter and the area of a polygon?
*March 13, 2012*

**Chemistry**

Assume you begin with 60 g of water at 20 oC and 60 g of water at 80 oC. After adding the two portions of water into your calorimeter, you determine the temperature of the mixed portions of water to be 45 oC. What is the heat capacity of the calorimeter?
*March 12, 2012*

**organic chemistry**

How many steric interactions are there in CIS-1,3-dimethylcyclohexane? Which groups participate in the interactions and whats the total number of interactions of this type??? Also, if i have the steric strain value for one 1,3 H-CH3 interaction, how can i determine the ...
*March 12, 2012*

**Chemistry**

Given the data below, calculate the total heat (in J) needed to convert 20.0 g of liquid ethanol (C2H5OH) at 40.0 oC to gaseous ethanol at 125 oC. A. 3.23 x 103 B. 3.67 x 103 C. 4.17 x 103 D. 2.08x104 E. 2.12 x 104
*March 8, 2012*

**AP Chemistry**

Calculate the pH of each of the following buffered solutions: a. 0.10M C2H5NH2/0.25M C2H5NH3Cl b. 0.25M C2H5NH2/0.50M C2H5NH3Cl c. 0.50M C2H5NH2/0.50M C2H5NH3Cl
*March 8, 2012*

**chemistry**

Liquid nitrogen-powered car students at the university of north Texas and the university of Washington built a car propelled by compressed nitrogen gas. The gas was obtained by boiling liquid nitrogen stored in a 185.0 L tank what volume of N2 is released at 0.900 atm or ...
*March 5, 2012*

**biology**

Question 18 If a child was allergic to a substance scratched onto their skin, the area turned red and swollen within about 10 minutes. Which of the following would cause these symptoms? Answer Release of interleukin-10 Recruitment of B cells Release of histamine The presence ...
*March 4, 2012*

**biology**

If a child was allergic to a substance scratched onto their skin, the area turned red and swollen within about 10 minutes. Which of the following would cause these symptoms? Answer Release of interleukin-10 Recruitment of B cells Release of histamine The presence of flatworms...
*March 4, 2012*

**biology**

If a child was allergic to a substance scratched onto their skin, the area turned red and swollen within about 10 minutes. Which of the following would cause these symptoms?
*March 4, 2012*

**astronomy**

What is the tempertaure range for objects whose wavelength at maximum falls within the visible spectrum, 400 to 700 nm?
*March 4, 2012*

**allterations **

Senteces for allterations
*March 2, 2012*

**math**

Carl have a budget of $290. Explain how you would find amount Carl spent on books.
*February 28, 2012*

**physics**

A cyclist enters a curve of 30 m radius at a speed of 12 m s-1. He applies the brakes and decreases his speed at a constant rate of 0.5 m s-2. Calculate the cyclist’s centripetal (radial) [3 marks] and tangential [15 marks] accelerations when he is travelling at a speed ...
*February 28, 2012*

**physics**

During a throw an athlete exerts a net average torque of 100 Nm on a discus about its axis of spin. The mass of the discus is 2 kg and its radius of gyration about its spin axis is 12 cm. If the discus was not spinning at the beginning of the throw and the throwing action ...
*February 28, 2012*

**physics**

An athlete is supporting a weight of 200N in his hand with his forearm at a right angle to his biceps. Assuming his biceps are in the vertical plane, the axis of rotation of the forearm is 3 cm from the elbow and 25 cm from the centre of gravity of the weight, calculate the ...
*February 28, 2012*

**physics**

A boy of mass 23 kg sits on a seesaw 1.5 m from the axis of rotation. At what distance from the axis of rotation must his friend, whose mass is 21 kg, be positioned to balance the seesaw? [6 marks]
*February 28, 2012*

**physics**

As part of a training schedule a weightlifter pushes a heavy metal block along the floor. The lifter applies a force of 850 N downwards on the block at an angle of 65° to the vertical (25° to the horizontal). The weightlifter pushes the block forwards 4 m in 1.6 s. ...
*February 28, 2012*

**physics**

A puck of mass 5.0 kg moving at 16.5 m/s approaches an identical puck that is stationary on frictionless ice. After the collision, the first puck leaves with a speed v1 at 30º to the orginal line of motion. The second puck leaves with speed v2 at 60º. The speed v1 ...
*February 26, 2012*

**physics**

A puck of mass 5.0 kg moving at 16.5 m/s approaches an identical puck that is stationary on frictionless ice. After the collision, the first puck leaves with a speed v1 at 30º to the orginal line of motion. The second puck leaves with speed v2 at 60º. The speed v1 ...
*February 26, 2012*

**3 grade english**

Jimmy likes checkers, and he is very good at playing it with his mom. Pronouns are "he" and "it" They have lots of fun playing it because they spend time together. Pronouns are "They" and "it" Sometimes, Jimmy's dad plays with them, ...
*February 24, 2012*

**Chem**

how much energy is required to change 42.5 g of molten aluminum into aluminum vapor
*February 22, 2012*

**Living ENvironment**

no am doing a project and i have to label the parts of the diagram if they are enzyme/substrate complex , active site and etc
*February 22, 2012*

**Living ENvironment**

Where is the Enzyme/substrate complex
*February 22, 2012*

**Physics**

A computer is reading data from a rotating CD-ROM. At a point that is 0.0368 m from the center of the disk, the centripetal acceleration is 274 m/s2. What is the centripetal acceleration at a point that is 0.0781 m from the center of the disc?
*February 19, 2012*

**Physics**

Two satellites are in circular orbits around Jupiter. One, with orbital radius r, makes one revolution every 18 h. The other satellite has orbital radius 3.9r. How long does the second satellite take to make one revolution around Jupiter?
*February 18, 2012*

**Chemistry**

KI+H2SO4 Write the balanced net ionic equation.
*February 17, 2012*

**Chemistry**

NaBr+H2SO4 Write the balanced net ionic equation.
*February 17, 2012*

**Chemistry**

NaCl+H2SO4 Write the balanced net ionic equation.
*February 17, 2012*

**Chemistry**

3Ag(s)+4HNO3(aq)-->3AgNO3(aq)+NO(g)+2H2O(l) Write the net ionic equation.
*February 17, 2012*

**3rd grade math**

write the missing fraction or mixed number for each number line 0,1/3,2/3,1,____,____,____,______,2 1/3 3
*February 16, 2012*

**Chemistry**

This topic's pretty old, but I figured it would be worth it to have the new way to solve the problem posted as well. If you're like me you're a young whippersnapper who's never even heard of normality. It's actually not as hard as DrBob says. Molarity = ...
*February 16, 2012*

**english**

2. Marion needs to believe in a ____ (1 point)
*February 15, 2012*

**Math**

76 girls
*February 13, 2012*

**College Chemistry**

If the density of cylinder 1 is 3.55 , what is the density of cylinder 2? (The masses and volumes of two cylinders are measured. The mass of cylinder 1 is 1.35 times the mass of cylinder 2. The volume of cylinder 1 is 0.792 times the volume of cylinder 2.)
*February 12, 2012*

**math**

If a metal ball is thrown downward with an initial velocity of 22 feet per second (15mph)from a 100 foot water tower, it's height h in feet above the ground after t seconds is modeled by h(t)=-16t^2-22t+100 Determine when the height of the ball is 62 feet.
*February 12, 2012*

**algebra**

The strength of a wood beam varies inversely with its length. A beam is 33 feet long can support 1200 pounds. How much weight can a similar beam support if it is 23 feet long?
*February 11, 2012*

**maths/physics/biomechanics**

At the beginning of a race, a yacht crosses the start line and sails in westerly direction at a speed of 4 m s-1. The current of the sea is flowing at 2 m s-1 towards the north-east. Calculate how far [8 marks] and in what direction (relative to west) [8 marks] the yacht has ...
*February 9, 2012*

**chemistry**

Which of the following isotopes possesses a greater number of electrons than it does neutrons? A. 40Ar B. 24Mg2+ C. 34S2− D. 19F− E. 16O2− How do I determine the numbers of protons, neutrons, and electrons of each?
*February 9, 2012*

**physics**

A 2.00kg bullet moving at 600m/s strikes a piece of wood at rest on a frictionless table. The bullet sticks in the wood and the combined mass moves slowly down the table. a.) What is the speed of the combined mass after the collision? b.)What is the change in kinetic energy of...
*February 9, 2012*

**chemistry**

A graduated cylinder was used to transfer 201 mL of a 0.478 M solution of KCl to a beaker which was subsequently diluted to a final volume of 1.092 L. What is the final molarity of the KCl in the beaker after the solution is thoroughly mixed?
*February 8, 2012*

**Chemistry**

thanks!
*February 8, 2012*

**chem**

How many grams of water vapor (H2O) are in a 10.2 liter sample at 0.98 atmospheres and 26°C? Show all work used to solve this problem.
*February 8, 2012*

**Chemistry**

rate is 1.1 ng/dL-hr
*February 8, 2012*

**Chemistry**

A deceased person is found by the coronoer to have a cocaine concentration of 50 ng/dL. What is the concentration of cocaine in his blood two hours earlier?
*February 8, 2012*

**mth174**

A tank is full of water. Find the work W required to pump the water out of the spout. (Use 9.8 for g and 3.14 for π. If you enter your answer in scientific notation, round the decimal value to two decimal places. Use equivalent rounding if you do not enter your answer in ...
*February 7, 2012*

**maths**

At the beginning of a race, a yacht crosses the start line and sails in westerly direction at a speed of 4 m s-1. The current of the sea is flowing at 2 m s-1 towards the north-east. Calculate how far [8 marks] and in what direction (relative to west) [8 marks] the yacht has ...
*February 7, 2012*

**maths**

Two athletes are pulling on a ring. One athlete pulls with a force of 150 N in a northerly direction. The second athlete pulls with a force of 200 N in a westerly direction. Calculate the magnitude [5 marks] and direction (relative to west) [5 marks] of the resultant of these ...
*February 7, 2012*

**physics**

A 75 kg skydiver in free fall is subjected to a crosswind exerting a force of 60 N and to a vertical air resistance force of 100 N. Calculate the resultant force acting on the skydiver [6 marks] and his angle of fall (relative to vertical) [6 marks].
*February 7, 2012*

**Physics**

A driver in a car traveling at a speed of 56.0 mi/h sees a deer 116 m away on the road. Calculate the minimum constant acceleration that is necessary for the car to stop without hitting the deer (assuming that the deer does not move in the meantime).
*February 2, 2012*

**Physics**

I have found that it takes the lead car 11.95 s to stop and it traveled 146.4 m. But still need help with the rest.
*February 2, 2012*

**Physics **

Two cars are traveling along a straight line in the same direction, the lead car at 24.5m/s and the other car at 29.8m/s. At the moment the cars are 41.4m apart, the lead driver applies the brakes, causing her car to have an acceleration of -2.05m/s2. A) How long does it take ...
*February 2, 2012*

**Physics **

Two cars are traveling along a straight line in the same direction, the lead car at 24.5m/s and the other car at 29.8m/s. At the moment the cars are 41.4m apart, the lead driver applies the brakes, causing her car to have an acceleration of -2.05m/s2. A) How long does it take ...
*February 2, 2012*

**Physics**

tortoise= 10.1 t hare= 195.94(t-122) tortoise - hare= 10.1t - 195.94t + 23904.68 = 20.8 Solve for t 23883.88 = 185.84 t t = 128.5185 s tortoise t= (10.1)(128.5185)= 129.036 cm
*February 2, 2012*

**Math**

afraaz the answer of 12.5 is not correct, i had done the same math as you did, however the teacher said that the answer was wrong.
*February 1, 2012*

**Physics**

A diver springs upward from a board that is 4.10 m above the water. At the instant she contacts the water her speed is 11.9 m/s and her body makes an angle of 79.7 ° with respect to the horizontal surface of the water. Determine her initial velocity, both (a) magnitude and...
*January 31, 2012*

**math**

17*5=85 17+5=22
*January 31, 2012*

**physics**

I found the answer to part a, but I don't know how to solve part b. Part is 26.1m/s.
*January 31, 2012*

**physics**

A space vehicle is coasting at a constant velocity of 22.5 m/s in the +y direction relative to a space station. The pilot of the vehicle fires a RCS (reaction control system) thruster, which causes it to accelerate at 0.223 m/s2 in the +x direction. After 57.5 s, the pilot ...
*January 31, 2012*

**math**

math : write an equation that uses 18-?and 10+2.explain how to decide which numbers would make it true.
*January 30, 2012*

**Math**

Red and blue beads are being strung to make a bracelet. How many different bracelets can be formed it each bracelet uses exactly 5 beads?
*January 29, 2012*

**geometry**

Simplify the ratio: 48 ft. -------- 36 ft.
*January 27, 2012*

**Problem Solving: Make a Table**

1st week=$50 2nd week=$75 3rd week=$100 4th week=$125 5th week=$150 6th week=$175 7th week=$200 TOTAL=$875
*January 25, 2012*

**World History**

28.Olympe de Gouges
*January 23, 2012*

**physics**

In reaching her destination, a backpacker walks with an average velocity of 1.20 m/s, due west. This average velocity results, because she hikes for 5.94 km with an average velocity of 3.28 m/s due west, turns around, and hikes with an average velocity of 0.778 m/s due east. ...
*January 22, 2012*

**Physics**

Two iron spheres each have a volume of 10 cm^3 and a mass of 78g. How many electrons must be placed on each sphere so that the electrostatic force of repulsion between them just balances the force of gravitational attraction? Assume the distance between the spheres is more ...
*January 21, 2012*

**science/anatomy**

1. pharynx 2. Epiglottis
*January 19, 2012*

**math**

I had the same question
*January 19, 2012*

**geometry**

the transamerica pyramid building shown in the photograph has four faces shaped like isosceles triangles. The measure of a base angle of one of these triangles is about 85. What is the approximate measure of the vertex angle of the triangle?
*January 17, 2012*

**Chemistry**

You can also use d=PM/RT. Density is mass/volume. Plug it in and solve for M.
*January 16, 2012*

**Science**

I put Individuals of the same kind living in the same environment make up a population. All the populations of organisma living together in an environment make up a community. Is that correct?
*January 12, 2012*

**Science**

In my book it says Individuals of the same kind living in the same evnironment make up a population. All the grasshoppers in a field are the grasshopper population. All the populations of organisms living together in an environment make up a community What is the relationship ...
*January 12, 2012*

**Science**

It's not C, right?
*January 12, 2012*