# Posts by Melissa

Total # Posts: 1,305

**pre-algebra**

a math professor is teachin two classes. The first class has 100 student enrolled and the second class has 75 estudent enrolled if 3/4 estudent of the first class pass and 2/5 student of the second class pass. how many estydent pass in total

*June 23, 2012*

**Calculus**

determine where f(x)={x^2-5x+6/x-3, if x<3 {1/x-2, if x>3 is discontinuous.

*June 19, 2012*

**physics**

The distance between successive crests in a series of water waves is 5.0m; the crests travel 8.6m in 5.0s . Calculate the frequency of a block of wood bobbing up and down in the water

*June 18, 2012*

**Finance**

Aset P has a beta of 0.9. The risk-free rate of return is 8%, while the return on the S&P 500 is 14%. Asset P's required rate of return is:

*June 17, 2012*

**physics**

Some children go tobogganing on an icy hill. The start from the rest at the top of the hill. The toboggan and children have a combined mass of 94 kg. The height of the first hill a is 12.0m the height of b is 0, and the height of c is 3.0m. If friction is small enough to be ...

*June 15, 2012*

**physics**

Your English teacher can swim with a constant speed of 0.67m/s. While facing south , he attempts to swim straight across the St. Lawrence River , which moves east at 1.4 m/s a) find his velocity as seen from the riverbank. B) if the river was 175m wide How long does it take ...

*June 14, 2012*

**physics**

An object falls from the top of the school, which is 6.06m high. Assume air resistance can be ignored and the acceleration is 9.8m/s^2 If the object was dropped( not thrown) , what is its speed after 0.333s How long does it take to hit the ground

*June 13, 2012*

**physics**

A spring with a spring-constant 2.2 N/cm is compressed 28 cm and released. The 5 kg mass skids down the frictional incline of height 31 cm and inclined at a 18◦ angle. The acceleration of gravity is 9.8 m/s2 . The path is frictionless except for a distance of 0.8 m along...

*June 12, 2012*

**physics**

A spring with a spring-constant 2.2 N/cm is compressed 28 cm and released. The 5 kg mass skids down the frictional incline of height 31 cm and inclined at a 18◦ angle. The acceleration of gravity is 9.8 m/s2 . The path is frictionless except for a distance of 0.8 m along...

*June 12, 2012*

**physics**

A formula one car is moving at mach 0.16 when the temperature of the air is 20.0c. What is the speed of the car in kilometers per hour?

*June 6, 2012*

**physics**

A plane traveling at 260m/s has a speed of Match 0.80. What is the speed of sound in the air

*June 6, 2012*

**physics**

Assuming that the speed of sound at a certain altitude is 330m/s calculate the speed of an airplane that is traveling at match 4.2 ?

*June 6, 2012*

**physics**

Thank you

*June 6, 2012*

**physics**

The source of a wave generates 25 crests and 25 troughs in 5.0s, and the distance between two successive crests in that wave is 1.5 m . What is the speed of the waves

*June 6, 2012*

**physics**

The distance between the second and sixth crests in a wave is 75cm and one crest travels a distance of 25 cm in 3.0s . Find the frequency of the wave

*June 6, 2012*

**physics**

The second resonant length of an open air column is 48cm. Determine the first and third resonant lengths

*June 5, 2012*

**physics**

Could you please explain how you got that! The answer should be 20.0cm and I just don't understand

*June 5, 2012*

**physics**

What's the shortest air column , closed at one end, that will resonate at a frequency of 440.0Hz when the speed of sound is 352 m/s

*June 5, 2012*

**physics**

Thanks:)

*June 5, 2012*

**physics**

The first resonant length of a closed air column occurs when the length is 30.0cm . What will the second and third resonant lengths be

*June 5, 2012*

**physics**

The third resonant length of a closed air column is 75cm . What is the first and second length

*June 5, 2012*

**physics**

A car sounds its horn (502 Hz) as it approachs a pedestrian by the side of the road. The pedestrian has perfect pitch and determines that the sound from the horn has a frequency of 520 Hz. If the speed of sound that day was 340 m/s , how fast was the car travelling

*June 4, 2012*

**physics**

Assuming that the speed of sound at a certain altitude is 330m/s calculate the speed of an airplane that is travelling at (A) mach 0.70

*June 4, 2012*

**physics**

A ship is traveling in fog parallel to a dangerous , cliff-lined shore. The boat whistle is sounded and its echo is heard clearly 11.0 s later. If the air temperature is 10.0 c , how far is the ship from the cliff.

*June 3, 2012*

**physics**

Calculate the speed of sound wave in air if its frequencies and wavelengths are 256Hz and 1.32m

*June 3, 2012*

**health**

According to the AMA, what is the key reason behind a physicians duty of confidentiality to a patient? Thanks in advance!!!

*June 2, 2012*

**statistics**

Given a level of confidence of 99% & a population standard deviation of 10, answer the following: (A)What other information is necessary to find the sample size (n)? (B)Find the Maximum Error of Estimate (E) if n=77. show all work.

*May 30, 2012*

**Chemistry**

Calculate the mass of silver bromide produced from 22.5 g of silver nitrate in the following rxn: 2AgNO3(aq) + MgBr2(aq)-->2AgBr(s)+ Mg(NO3)2 (aq)

*May 28, 2012*

**Math**

The present value of the money in your savings acct is $420, and you're receiving 3% annual interest compounded monthly. What is the future value in 2 months?

*May 27, 2012*

**american government**

Unitary government

*May 21, 2012*

**physics**

A bell is rung at a sound intensity of 70dB . A trumpet is blown at an intensity that is greater by a factor of 10^3. What is the intensity level of the trumpet

*May 20, 2012*

**physics**

A vibrating 400.0Hz tuning fork is placed in fresh water. What is the frequencyin herbs and the wavelength in meters (A) within the water at 25c (B) when the sound waves move into the air at 25c

*May 20, 2012*

**physics**

A fan at a baseball game is 100.0m from the home plate. If the speed of sound is 350 m/s , how long after the batter actually hits the ball does the fan hear the crack? Assume that there is no wind.

*May 20, 2012*

**physics**

A 200m dash along a straight track was timed at 21.1 s by a timer located at the finish line who used the flash from the starters pistol to start the stopwatch. If the air temperature was 30.0c , what would the time have been if the timer had started the watch upon hearing the...

*May 20, 2012*

**physics**

How much time is required for sound to travel 1.4 km through air if the temperature is 30.0 c

*May 20, 2012*

**physics**

I tried that but it does not give me the correct answer which is 0.204 m/s

*May 8, 2012*

**physics**

The motor for an elevator can produce 2200 W of power. The elevator has a mass of 1100 kg complete with contents . At what constant speed will the elevator rise ?

*May 8, 2012*

**physics**

How much work can a 22 kW car engine do in 60 seconds if It is 30% efficient It is 100% efficient

*May 8, 2012*

**physics**

A boy fires a 60 g pebble with his slingshot. The pebble leaves the slingshot at 35m/s How high above the slingshot will the pebble rise if it's fired straight up?

*May 8, 2012*

**Law**

In law we watched a movie called 12 angry men , and there is a question I am stuck on, any help would be great! How does the film 12 angry men deepen our understanding of the guarantee of the right to trail by jury and the role of the jury system in America democracy? Thank ...

*May 5, 2012*

**Life orientation**

1: In 10-15 lines critically discuss 5 ways in which the human or environmental problem impacts on the community ( HIV AIDS ). 2: Provide recommendations on how to address HIV AIDS. Thank you!:-)

*May 2, 2012*

**Life orientation**

Poverty, pollution, hiv aids, nutrition, floods. Name two institutions or community organizations that are involved in supporting or giving redress to these disasters. Explain how these organizations are involved in providing a safe and healthy environment.

*May 2, 2012*

**physics**

A chair lift takes skiers to the top of a mountain that is 320 m high. The average mass of skiers complete with equipment is 85 kg . The chair lift can deliver three skiers to the top of the mountain every 36 s Determine the power required to carry out this task If friction ...

*April 30, 2012*

**physics**

An archer locks a 0.20kg arrow on a bowstring. Then the archer exerts an average force of 110N to draw the string back 0.60 m . Assume that friction is negligible . What speed does the bow give to the arrow? If the arrow is shot vertically upward,how high will it rise?

*April 30, 2012*

**physics**

two ropes are tied to a large boulder. one rope is pulled with a force of 400N due east. The other rope is pulled with a force of 300N due south. draw a vector diagram showing the forces

*April 28, 2012*

**physics**

A 6.0g pellet of lead at 32 degrees c gains 36.8 J of heat. What will be its final temperature

*April 27, 2012*

**physics**

A 50.0kg cyclist on a 10.0kg bicycle speeds up from 5.0m/s to 10.0m/s , the total kinetic energy before acceleratingis 750, and after acceleratingis 3000, how much work is done to increase the kinetic energy of the cyclist and the bicycle

*April 27, 2012*

**Physics**

HELP PLEASE. Hypothetically, you are standing on the balcony of an apartment on the 10th level of a building and you throw a ball at some angle, 0 , above the horizontal away from the building. the ball lands on the ground 10m from the building, 3.2s after it was thrown. the ...

*April 26, 2012*

**physics**

A 60 kg student does 60 push ups in 40s . With each push up , the student must lift 70% of the body mass a height of 40cm off the floor. Assuming two significant digits, calculate the following The work the student does against a force of gravity for each push up , assuming ...

*April 25, 2012*

**Chemistry**

If the acetylene were burned to form water and carbon dioxide, how many kilojoules of energy would be produced from the complete reaction of 20 of calcium carbide? CaC2(s)+2H2O(l) --> C2H2(g)+Ca(OH)2(s)

*April 23, 2012*

**Chemistry**

If the acetylene were burned to form water and carbon dioxide, how many kilojoules of energy would be produced from the complete reaction of 20 of calcium carbide? CaC2(s)+2H2O(l) --> C2H2(g)+Ca(OH)2(s)

*April 23, 2012*

**Physics**

Viscous blood is flowing through an artery partially clogged by cholesterol. A surgeon wants to remove enough of the cholesterol to double the flow rate of blood through this artery. If the original diameter of the artery is D , what should be the new diameter (in terms of D...

*April 23, 2012*

**math**

a rectangular field measures 20 meters by y meters is surrounded by grass patch of width 2 meters . What is the area of the grass patch ? Leave your answer in the simplest form in terms of y .

*April 21, 2012*

**math**

from one piece of wood , Sam cut two 9 1/2 in. strips for 2 sides of a frame. He cut two 11 3/4 in . strips each for the other 2 sides Sam had 5 1/2 in.of wood left. How long was the piece of wood when he started ?

*April 18, 2012*

**math**

1. Gina wants to begin by figuring out how long the corn bed will be. She knows that in her previous two gardens, she was able to plant 2 rows in a 5 foot long space and 5 rows in an 11 foot long space. Find a linear equation for the length of the bed (y) in which she can fit ...

*April 16, 2012*

**Chemistry**

This answer is still not correct for me!!

*April 15, 2012*

**statistics**

20. Explain how the power of a hypothesis test is influenced by each of the following. Assume that all other factors are held constant. a. Increasing the alpha level from .01 to .05. b. Changing from a one-tailed test to a two-tailed test.

*April 14, 2012*

**physics**

Write the energy transformation equation for each situation Fireworks explodes An arrow is shot off a bow and flies through the air A paved driveway feels hot on a clear ,sunny day A camper raises an axe to chop a chunk of wood A lawn mower with a gasoline engine cuts a lawn

*April 12, 2012*

**Physics**

how does the slope of a Ff-Fg graph relate to the coefficients of friction , prove it mathematically.

*April 12, 2012*

**physics**

A 12 kg toboggan is pulled along at a constant velocity on a horizontal surface by a horizontal force of 11 N How much horizontal force is needed to pull the toboggan at a constant velocity if two 57 kg girls are sitting in it ?

*April 10, 2012*

**science**

a 40kg student goes to jupiter where the rate of acceleration is 24.5m/s squared what is the students weight on jupiter?

*April 10, 2012*

**chemistry**

Which of the following measures thermal energy in an object? (Points : 4) temperature mass heat volume

*April 9, 2012*

**physics**

A wagon is used to help deliver papers. There is a force applied at an angle of 25 degrees to the horizontal that causes the wagon to move a distance of 15m[N] in 10.0s from rest. There is a force of friction of 3.1 N acting on the 27kg wagon. What is the acceleration of the ...

*April 9, 2012*

**Calculus**

Verify if correct. Determine which line is parallel to the line with Cartesian equation 2x +3y + 5=0 a) r=(-1,-1) +s(2,3), seR b) x=3t-1, y=-2t-1, teR c) x=2t-1, 3t-1, teR d) none of the above. I chose D, none of the above because none of them are multiples of the given ...

*April 7, 2012*

**Calculus**

Explain fully please and thank you! =) Determine the point of intersection of the lines L1: r= (1,3,7) + s(1,2,-2),seR and L2: v=(0,2,-3) +t(1,1,4), teR. a) P(1,3,1) b P(1,3,7) c) The lines coincide d) no point of intersection

*April 7, 2012*

**physics**

Determine the magnitude of the force of gravity acting on a 340 kg satellite , 850 km above Earth's surface.

*April 6, 2012*

**physics**

A tug of war has started over a popular toy. One child pulls with a force of 2.0*10^1 N[W], a second child pulls with a force of 15N[N] and a third child pulls with a force of 4.0*10^1 N [30 S of E] calculate the net force on the toy

*April 5, 2012*

**physics**

If the coefficient of kinetic friction is 0.25 , how much horizontal force is needed to pull each of the following masses along a rough desk at a constant speed? A) 25 kg

*April 5, 2012*

**physics**

A 650 N student is Rollerblading at a velocity of 7.8 m/s [W] when the student trips and slides horizontally along the trail, coming to a stop 0.95s. Determine the students average acceleration

*April 5, 2012*

**physics**

Determine the magnitude of the force of gravity acting on a 340 kg satellite, 850 km above Earth's surface

*April 5, 2012*

**physics**

How do i find the acceleration though

*April 4, 2012*

**physics**

Given the following forces acting on an object find the net force: 2.0N[N], 10N[S], 2.0N[W], 8.0N[E] The mass is 5.1 kg with the net force find the objects acceleration

*April 4, 2012*

**physics**

Two children on the beach are pulling on an inner tube. One exerts a force of 45 N[N]. The other exerts a force of 60N[SW]. What is the net force acting on the tube

*April 3, 2012*

**physics**

Two children on the beach are pulling on an inner tube. One exerts a force of 45 N[N]. The other exerts a force of 60N[SW]. What is the net force acting on the tube

*April 3, 2012*

**physics**

Two children on the beach are pulling on an inner tube. One exerts a force of 45 N[N]. The other exerts a force of 60N[SW]. What is the net force acting on the tube

*April 3, 2012*

**physics**

Two children on the beach are pulling on an inner tube. One exerts a force of 45 N[N]. The other exerts a force of 60N[SW]. What is the net force acting on the tube

*April 3, 2012*

**physics**

Two children on the beach are pulling on an inner tube. One exerts a force of 45 N[N]. The other exerts a force of 60N[SW]. What is the net force acting on the tube

*April 3, 2012*

**physics**

The force of gravity at Earth's surface on an astronaut is 634N. What is the force of gravity on the same person at each of the following distances, in multiples of Earth's radius, from the centre of Earth? A)2 B)5 C)10 D)17.2

*April 2, 2012*

**physics**

The mass of Earth can be calculated using the fact that the weight of an object (in newtons) is equal to the force of gravity between the object and Earth. Given that the radius of Earth is 6.4*10^6m , determine its mass

*April 2, 2012*

**physics**

Any my text book for the 12.0kg steel ball it says the answer is 1.2*10^2N, not 117.6N how did they get that answer?

*April 1, 2012*

**physics**

Calculate Earth's force of gravity on each of two steel balls of masses 6.0kg and 12.0kg I the forces of gravity on the 12-kg ball is greater than that on the other ball, why do the two balls accelerate at the same rate when dropped?

*April 1, 2012*

**trig**

389 miles

*March 28, 2012*

**Trigonometry**

A ladder that is 15 feet long is placed so that it reaches from level ground to the top of a vertical wall that is 13 feet high A. Use the law of sines to find the angle that the ladder makes with the ground to the nearest hundredth B. Is more than one position of the ladder ...

*March 27, 2012*

**physics**

When the crampton coal-fired train engine was built in 1852 , its mass was 48.3t ( 1.0 t= 1.0*10^3) and its force capability was rated at 22.4 kN. Assuming it was pulling train cars whose total mass doubled its own was and the total friction on the engine and cars was 10.1 kN...

*March 25, 2012*

**physics**

When the crampton coal-fired train engine was built in 1852 , its mass was 48.3t ( 1.0 t= 1.0*10^3) and its force capability was rated at 22.4 kN. Assuming it was pulling train cars whose total mass doubled its own was and the total friction on the engine and cars was 10.1 kN...

*March 25, 2012*

**physics**

Lol :) thanks , i should have thought of that

*March 25, 2012*

**physics**

According to newtons 1st law , construction workers are warned not to leave their hard hats on the rear window ledge of their cars, explain why?

*March 25, 2012*

**physics**

Sorry i meant 4000 kg is the mass

*March 25, 2012*

**physics**

A jet plane pilot decides to accelerate horizontally. If the thrust of the engine is increased to 50 000 N at a time when the air resistance ( or drag) acting on the 4000kg plane amounts to 30 000 N , what will the planes acceleration be I believe you at the 50 000 and the 30 ...

*March 25, 2012*

**physics**

Thank you so much I understand now !

*March 25, 2012*

**physics**

How much applied force is needed to accelerate a 2.0 kg block of wood at 4.0m/s^2 along a rough table, against a 10 N force of friction?

*March 25, 2012*

**physics**

Thank you for helping me ! It takes me a little bit longer to grasp concepts, i think now the correct answer is it is unbalanced because it accelerates?

*March 25, 2012*

**physics**

Is the net forces balanced because it accelerates steadily in a straight line?.

*March 25, 2012*

**physics**

I have no clue we never covered it in class!

*March 25, 2012*

**physics**

A 1200 kg boat accelerates steadily at 0.05 m/s^2 in a straight line . Are the forces on this boat balanced or unbalanced?

*March 25, 2012*

**physics**

The force of friction is zero?

*March 25, 2012*

**physics**

A woman pushes a refrigerator across the floor at a steady speed of 20cm/s . If she has to push with a horizontal force of 400 N to keep it moving , is the force of friction less than 400 N , 400 N, more than 400 N, why

*March 25, 2012*

**physics**

Thank you so much, i understand a lot more now !

*March 25, 2012*

**physics**

A jet plane is traveling at a constant speed in a straight line in level speed. What does this tell you about the forces acting on it, what forces are acting on it .

*March 25, 2012*

**physics**

thank you bobpursley

*March 23, 2012*