Tuesday
October 21, 2014

Posts by SARA


Total # Posts: 3,734

Physics
A car of mass 1100 kg starts from rest at sea level and climbs a hill of altitude 50 m. At the top of the hill the car has a speed of 25 m/s. From the top of the hill the driver turns off the engine and coasts down to an altitude of 15 m. Assume the friction and the air ...
October 27, 2012

Physics
A car of mass 1100 kg starts from rest at sea level and climbs a hill of altitude 50 m. At the top of the hill the car has a speed of 25 m/s. From the top of the hill the driver turns off the engine and coasts down to an altitude of 15 m. Assume the friction and the air ...
October 26, 2012

Physics
A car of mass 1100 kg starts from rest at sea level and climbs a hill of altitude 50 m. At the top of the hill the car has a speed of 25 m/s. From the top of the hill the driver turns off the engine and coasts down to an altitude of 15 m. Assume the friction and the air ...
October 25, 2012

calculus
A street light is mounted at the top of a 6-meter-tall pole. A man 2 m tall walks away from the pole with a speed of 1.4 m/s along a straight path. How fast is the tip of his shadow moving when he is 16 m from the pole?
October 16, 2012

college orgo
calculate how to make 10 mL of 15:85 ethyl acetate:hexane solution from 2 mL of 5:95 ethyl acetate:hexane, using pure hexane and pure ethyl acetate.
October 15, 2012

Physics
Never mind, figured it out.
October 14, 2012

Physics
A wagon is rolling forward on level ground. Friction is negligible. The person sitting in the wagon is holding a rock. The total mass of the wagon, rider, and rock is 97.0 kg. The mass of the rock is 0.320 kg. Initially the wagon is rolling forward at a speed of 0.540 m/s. ...
October 14, 2012

Physics
87 09 7
October 9, 2012

science
I dissolved two different white solids into water. One solid dissolved and gave off heat and the other became cold. Reading various texts online, I was not sure if these were physical or chemical changes. Some texts say if these solids are salts then these are physical changes...
October 8, 2012

physics
A jogger runs down the street at a rate of 1.1 m/s. She sees the finish line, and speeds up to a velocity of 3.6 m/s over 1.1 s. What is the acceleration of the jogger?
October 3, 2012

physics
A ball is dropped from a height of 18.6 m. What is the velocity of the ball the instant it hits the ground?
October 3, 2012

Math does anyone know this?
I have to state whether these equations are parallel or perpendicular y=4x+6 y-4x=-1
October 3, 2012

physics
Sarah shoots a toy dart vertically downward at 11.7 m/s at Mark standing on the ground below. Calculate the dart's velocity after 0.8 seconds.
September 30, 2012

physics
Sarah shoots a toy dart vertically downward at 11.7 m/s at Mark standing on the ground below. Calculate the dart's velocity after 0.8 seconds.
September 30, 2012

bridge to terabitha
Hello i read the book bridge to terabitha and i have an assignment i need some help on. i need to pick 5 characters and describe six events or circumstances that caused the character to change or evolve. i have picked the characters Jesse Oliver Aarons Leslie Burke Mrs. Aarons...
September 30, 2012

math
how do u multiply a positive number and a negitave number
September 26, 2012

science
Draw the condensed structures of the esters formed from the following reactants. Name the compound in each case. (a) butanoic acid and methanol
September 25, 2012

math
There are 5 purple, 3 yellow, and 4 pink rocks in a jar. What is the chance of getting a purple rock if it was pulled out of the jar without looking?
September 25, 2012

chem
Using condensed structural formulas, write a balanced chemical equation for each of the following reactions a)addition of H2O to trans-2-pentene using H2SO4 as a catalyst (two products) i got 2-pentanol adn 3-pentanol but it is counting it wrong!
September 25, 2012

Chemistry
A 2.914 gram sample of gypsum, a hydrated salt of calcium sulfat, CaSO4, is heated at a temperature greater than 170 degrees Celcius in a crucible until a constant mass is reached. The mass of the anhydrous CaSO4 salt is 2.304 grams. Calculate the percent by mass of water in ...
September 24, 2012

math help?
2x+4 (2x+6) I did this and ended up with a decimal number. I distributed then combined like terms.
September 21, 2012

chemistry
The atomic mass of chlorine is listed as 35.454 amu on the periodic table. It has two naturally occurring isotopes, CI-35 and CI-37. What are the approximate percentage of each?
September 20, 2012

PHYSICS
Suppose a moose jumps straight up with an initial upward velocity of 95 m/s. How long until the ungulate lands back on the ground, where it belongs?
September 17, 2012

PHYSICS
If a DeLorean rolls gently (vo = 0) off a vertical cliff, how long does it take it to reach a downward velocity of 78 km/h?
September 17, 2012

physics
Suppose a moose jumps straight up with an initial upward velocity of 95 m/s. How long until the ungulate lands back on the ground, where it belongs?
September 17, 2012

physics
Cubs outfielder Alfonso Soriano catches a ball 5.2 s after throwing it vertically upward. How high did the ball go, relative to his hand?
September 17, 2012

physics
A falling iPad takes 0.16 s to travel past a window 2.1 m tall. From what height above the top of the window did the mobile device fall?
September 17, 2012

physics
If a DeLorean rolls gently (vo = 0) off a vertical cliff, how long does it take it to reach a downward velocity of 78 km/h?
September 17, 2012

physics
A sophomore chemistry student holds a 500mL Erlenmeyer flask full of concentrated nitric acid high above his head at a height of 1.75 meters and declares, "I'm the King of Chemistry!" At that moment another student, startled by the sudden ignition of her Bunsen ...
September 17, 2012

botany
what is the difference between primary walls and secondary walls in plants. (specifically sclerencyma cells- which have secondary and parenchyma and collenchyma - which just have primary walls
September 16, 2012

chem
Draw the three distinct geometric isomers of 2,4-hexadiene. i can draw what it is giving. but i do not get what the geometric isomers are? if you drew it a different way wouldnt that change the name?
September 15, 2012

Algebra..
Help? If f = (1, 2), (2, 3), (3, 4), (4, 5), g = (1, -2), (3, -3), (5, -5), and h = (1, 0), (2, 1), (3, 2), 1. f+g 2. f-g 3. f*g
September 14, 2012

Algebra..
f(x)= x^2+3 ; g(x)=3x-1 Check These Please? 1.(fg)(-1) = 5 2. (f o g)(1) =10 How would you solve this? 1. (g o f)(x)
September 14, 2012

physics
A ping pong ball is rolling across a table at 2.1 cm/s. When the ball is 1.32 m away from the edge your little brother starts to blow on it. If the little doofus hopes to prevent the ball from falling off the edge, what minimum acceleration must be achieved?
September 13, 2012

PHYSICS
A Cessna 350 must reach a speed of 35 m/s for takeoff. If the plane accelerates at a steady 3.8 m/s2, how long must the runway be?
September 13, 2012

PHYSICS
When moving at highway speed, a Triumph America motorcycle is capable of accelerating at 2.1 m/s2. At this rate, how long does it take to accelerate from 103 km/h to 88 km/h?
September 12, 2012

PHYSICS
A ping pong ball is rolling across a table at 2.1 cm/s. When the ball is 1.32 m away from the edge your little brother starts to blow on it. If the little doofus hopes to prevent the ball from falling off the edge, what minimum acceleration must be achieved?
September 12, 2012

chem
Cobalt-60, which undergoes beta decay, has a half-life of 5.26 yr. (a) How many beta particles are emitted in 47.0 s by a 2.39-mg sample of 60Co? i got 2.44e19 but thast wrong
September 12, 2012

physics
When moving at highway speed, a Triumph America motorcycle is capable of accelerating at 2.1 m/s2. At this rate, how long does it take to accelerate from 103 km/h to 88 km/h?
September 12, 2012

physics
The minivan your mom lets you drive accelerates from 12 m/s to 24 m/s in 6.5 s. How far does it travel in this time? Assume constant acceleration.
September 12, 2012

chem please help!
The average energy released in the fission of a single uranium-235 nucleus is about 3. 10-11 J. If the conversion of this energy to electricity in a nuclear power plant is 45% efficient, what mass of uranium-235 undergoes fission in a year in a plant that produces 2000 megawatts
September 11, 2012

Algebra..
Help? If f = (1, 2), (2, 3), (3, 4), (4, 5), g = (1, -2), (3, -3), (5, -5), and h = (1, 0), (2, 1), (3, 2), Find and state the domain. 1. f+g 2. f-g 3.f*g
September 11, 2012

pre algebra
show the work for 136.8 divided by 3600
September 10, 2012

Physics
A baseball batter hits a long fly ball that rises to a height of 49 m. An outfielder on the opposing team can run at 7.7 m/s. What is the farthest the fielder can be from where the ball will land so that it is possible for him to catch the ball?
September 10, 2012

chem
A 73-kg person is accidentally exposed for 215 s to a 16-mCi source of beta radiation coming from a sample of 14C. What is the activity of the radiation source in disintegrations per second? In becquerels? i am not sure if there is an equation for this or wut??
September 10, 2012

chem
do you know how to do it using hte numbers. I know for some problems uneeded information can be added but usually if its more than 2 peices then you use at least one of them
September 10, 2012

chem
it said that answers were wrong im pretty sure i have to use the 73 kg and 215 seconds.. or why would they put that in the question?
September 10, 2012

chem
I am not sure if there is an equation for this problem or wut?? A 73-kg person is accidentally exposed for 215 s to a 16-mCi source of beta radiation coming from a sample of 14C. What is the activity of the radiation source in disintegrations per second? In becquerels? (1 Ci...
September 10, 2012

algebra
art's age is two thirds cal's age, and bob is three years older than art. the sum of their three ages is 45. find the age of each one
September 8, 2012

Physics
A swimmer heads directly across a river, swimming at 1.10 m/s relative to the water. She arrives at a point 60.0 m downstream from the point directly across the river, 80.0 m wide. What is the speed of the river current? What is the swimmer's speed relative to the shore? ...
September 6, 2012

math
Two bulldozers clear homes from a 20-acre tract of land. One works twice as fast as the other. It takes them three days to clear the tract working together. How long would it take each of them alone? whats the equation?
September 6, 2012

chemistry help!!
I entered the asnwer I got and it is wrong.
September 5, 2012

chemistry help!!
thanks! so k=1.669e-11 so ln(65.3/45.9)=1.669e-11(t) so does t=2.112e10 years?
September 5, 2012

chemistry help!!
The half-life for the process 238U 206Pb is 4.5 109 yr. A mineral sample contains 45.9 mg of 238U and 16.8 mg of 206Pb. What is the age of the mineral? i used the equation: n(T)=n(O)/2^(t/halflife) and i got 6.53e9 but it is wrong. what am i doing wrong?
September 5, 2012

math
It just intersects at the point (0, -7), right?
September 5, 2012

math
So does this polynomial, when graphed, intersect the x-axis or it just comes close?
September 5, 2012

math
how many real roots does the polynomial 2x^5+8x-7 have
September 5, 2012

statistics
Thanks for the guidance. Does it make sense that I would get 1? 1. z = (x - μ) / σ z = (84-100)/8 z = -16/8 z = -2 and z = (116-100)/8 z = 16/8 z = 2 area = .0228+.9772 Area = 1
September 4, 2012

statistics
The mean of a normal probability distribution is 100 and the standard deviation is 8. About what percent of the observations lie between 84 and 116?
September 4, 2012

Discrete Mathematics
Mathematical sequences can be used to model real life applications. Suppose you want to construct a movie theater in your town. The number of seats in each row can be modeled by the formula C_n = 16 + 4n, when n refers to the nth row, and you need 50 rows of seats. (a) Write ...
September 4, 2012

math
for #1, where did you get the negative for - ( x+ 4 )
September 4, 2012

math
I tried solving these problems and get stuck . Can you please tell me what am I suppose to do next or did I do them all wrong 1. (x+5)^2 = (x+4)^2 √(x+5)^2 = √(x+4)^2 x+5 = x+4 ? 2. (4x+7)^2 = 144 √(4x+7)^2 = √144 4x+7 = 12 ? 3. (x-5)^2 = 30 √(x-5...
September 4, 2012

Physics
You drop a rock off a bridge. 4. (2 pts) How fast is it going after 2.0 s?
September 2, 2012

chem
i think it stands for alpha. so would i just do the U + alpha -> neutron +Pu?
August 31, 2012

chem
Write balanced equations for the following reactions. (Use the lowest possible coefficients. Omit states-of-matter in your answer. 238 U 92 (á, n) 241 Pu 94 sorry teh formating is off
August 31, 2012

math
lithium citrate comes in 300 mg/5ml. the doctor calls and asks you to compound lithium citrate ''light'' (75mg/5ml). How would you dilute the citrate to proper dose?
August 29, 2012

stumping question
what is the difference between hydrofluoric acid and hydrogen fluoride. arnt they both HF?
August 29, 2012

U.S. History
I don't really understand the Spanish Colonial Empire during 33,000 b.c. to a.d. 1769 Who where involved? What was this? When did this take place? Where did this take place? Why is it so important?
August 29, 2012

Reading
May you please help me understand these questions? Thanks! 1. What does Spaz's story reveal about Spaz's origins? 2. With what is Spaz afflicted? In why way is it a blessing?
August 27, 2012

Physics
A helicopter is traveling with a velocity of 12 m/s directly upward. Directly below the helicopter is a very large and very soft pillow. As it turns out, this is a good thing, because the helicopter is lifting a large man. When the man is 20 m above the pillow, he lets go of ...
August 26, 2012

Physics
You are standing at the foot of the Bank of America building in San Francisco, which is 52 floors (237 m) high. You launch a ball straight up in the air from the edge of the foot of the building. The initial vertical speed is 70 m/s. a. How high up does the ball go? b. How ...
August 26, 2012

Reading
In this book I'm reading one of the questions ask: What is the significance of Bean finding the color blue? What does the question mean?
August 26, 2012

chem
what is the symbol for the element that has 78 protons 76 electrons 117 neutrons and a +2 net charge? i thought it was ^195Os^+2 but that is wrong. Thanks for the help!
August 25, 2012

Physic
If a clock in an airplane is found to slow down by 5 parts in 1013, (i.e., ∆t/∆to = 1.0 + 5.0 × 10. −13), at what speed is the airplane traveling? (Hint: You might need to use an expansion for y) I am not sure which equation to use can someone please ...
August 23, 2012

Physic
A sodium-vapour lamp illuminates, with monochromatic yellow light, two narrow slits that are 1.00 mm apart. if the viewing screen is 1.00m from the slits and the distance from the central bright line to the next bright line is 0.589 mm, what is the wavelength of the light? can...
August 23, 2012

Physics
On your wedding day your lover gives you a gold ring of mass 3.78 g. 50 years later its mass is 3.16 g. On the average how many atoms were abrated from the ring during each second of your marriage? The atomic mass of gold is 197 u
August 23, 2012

Social Studies
sorry. c?
August 22, 2012

Social Studies
is it d then?
August 22, 2012

Social Studies
Following on the successful activism of Cesar Chavez, Mexican American youths began to refer to themselves as A. Mexicans. B. Los Barrios. C. Chicanos. D. Los Hombres. is it a?
August 22, 2012

Social Studies
The 1978 Supreme Court decision in Bakke v. Regents of the University of California A. ruled in favor of affirmative action within specified limits. B. established the "red state-blue state" divide. C. established the rights of students to appeal college admissions ...
August 22, 2012

Social Studies
THE FIRST ONE IS WRONG
August 22, 2012

Social Studies
Which of the following statements about Truman's Fair Deal is true? A. It was reluctantly passed by Congress. B. It repealed the New Deal. C. It was Truman's response to the Soviet's Sputnik. D. It called for national medical insurance. is it d?
August 22, 2012

Social Studies
The majority of states that did not ratify the Equal Rights Amendment were located in the A. Midwest. B. Southeast. C. West. D. Northeast. is it B?
August 22, 2012

Social Studies
During World War II, the tide turned in favor of the United States at the Battle of A. Leyte Gulf. B. Okinawa. C. Midway. D. the Coral Sea. is it C??
August 22, 2012

Home economics
I need help on a hw question. Can a company bill you if you just give them your billing address or do they need a credit card number(or some type of payment)
August 21, 2012

Science
#9 is d?
August 21, 2012

Science
#3 is D?
August 21, 2012

Science
Okay. Is #1 B? Because it does support life. I know that. Coal isn't manufactured, & isn't in a liquid form, and it is organic. Is #9 b, as well?
August 21, 2012

Science
9. Which one of the following statements is characteristic of liquid water? A. It has a definite shape but not a definite volume. B. It has neither a definite shape nor a definite volume. C. It has a definite volume and a definite shape. D. It has a definite volume but not a ...
August 21, 2012

Physics
what is 5.76??
August 19, 2012

Physics
3 charges sit on vertical equilateral triangle the side of each is 30.0 cm. if the triangle are A= +4.0 uC B=+5.0 uC and C=+6.0 uC (clockwise from top) what is the force on each charge? Can someone please explain me in detail i am really confuse :(((
August 19, 2012

math
Sorry, I meant A.
August 18, 2012

math
The quotient of 5/31 divided by 15/23, reduced to the lowest fraction, is A. 23/93. B. 93/23 or 4 1/23. C. 75/373. D. 115/465. Is it b?
August 18, 2012

Math
D?
August 18, 2012

Math
The amount $180.00 is what percent greater than $135.00? A. 35% B. 75% C. 133.33% D. 33.33% Is it b?
August 18, 2012

MATH
You wish to mentally estimate the total cost of items that have the following prices: $1.85, $.98, $3.49, $9.78, and $6.18. Rounding off the items to the nearest half-dollar, your estimate of the total cost of these items is A. $22.50. B. $22.30. C. $22.59. D. $23.00. Is it A??
August 18, 2012

Physic
The field of an unknown charges is first mapped with a 1.0 X 10^-8 C test charges, then repeated with 2.0 X 10^-8 C test charge. a) would the same forces be measured with the two test charges (Explain)? b) would the same fields be determine using the two test charges (Explain)?
August 17, 2012

physical
But if i do this for force of friction, the result of frictional force is going to be negative. :(
August 17, 2012

physical
A 0.8 kg block of wood has an initial velocity of 0.25 m/s as it begins to slide across a table. The block comes to rest over a distance of 0.72m. a) what is the average frictional force on the block? b)How much work is done on the block by friction? c)How much work is done on...
August 17, 2012

physic
3 charges sit on vertical equilateral triangle the side of each is 30.0 cm. if the triangle are A= +4.0 uC B=+5.0 uC and C=+6.0 uC (clockwise from top) what is the force on each charge?
August 17, 2012

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