Thursday
November 20, 2014

# Posts by sarah

Total # Posts: 4,367

Physics
A .060kg tennis ball crosses the net a 40m/s and is returned back across the net at 36m/s by the other player. If the contact time between racket and the ball is .0250s, what is the average force on the ball?
May 9, 2012

Physics
A 50g bullet strikes a stationary 1.50kg block of wood paced on a horizontal surface just in front of the gun. The bullet becomes embedded in the block and the impact drives them a distance of 10m before they come to rest. If the coefficient of kinetic friction between the ...
May 9, 2012

Physics
A rocket car had a mass of 1650kg. The engine expels 140kg of combustion products in 7s. The expelled material has a velocity of 850m/s to the south. Calculate the velocity of the car at the end of 7s. ANSWER: 72m/s to the north
May 9, 2012

Physics
A bullet of mass 35g strikes a stationary wooden block of mass 2.6kg, becomes embedded in the block, and they both move off at 7.5m/s. What was the original velocity of the bullet?
May 9, 2012

Physics
object A of mass 3g with a velocity of 12cm/s to the east, collides with stationary object B. After collision, object A rebounds with a velocity of 10cm/s to the west and object B has a velocity of 1.5cm/s to the east. Calculate the mass of obeject B
May 9, 2012

Chemistry
Yes that makes a lot of sense now! Thank you so so much!:)
May 9, 2012

math-permutuation
a four digit serial number needs to be created using digits 0-9. first digit is even , no digit is repeated , last digit is odd
May 9, 2012

chemistry
What is the pH of a solution having a hydrogen ion concentration of 1x10^-5 M? Also the same question, but Hydroxide instead of hydrogen. thanks in advance!
May 9, 2012

Calculus
Approximate the sum of the series correct to four decimal places. n=1 to infinity (-1)^n/4^n*n!
May 8, 2012

PHYSICS
A tuning fork is set into vibration above a vertical open tube filled with water. The water level is allowed to drop slowly. As it does so, the air in the tube above the water level is heard to resonate with the tuning fork when the distance from the tube opening to the water ...
May 7, 2012

math
given f(x)=x^3+5x find the rate of change for the interval [0.5,0.51]
May 7, 2012

Physics
KE1= M1.v1'2/2 KE2= M2V2'2/2 KE1= [(1000kg)(277.89m'2/s'2)/2] = 138944.45J KE2= [(2000kg) (69.3889'2/s'2)/2] = 69388.9J KE1/KE2= 138944.45J/69388.9J =2.00
May 7, 2012

Physics
A king's crown is said to be solid gold but may be made of lead and covered with gold. when it is weighed in air, the scale reads 0.475 kg. when it is submerged in water the scale reads 0.437 kg.is it solid gold? if not, what percent is mass is gold? (density of gold= 19....
May 6, 2012

physics
A scuba diver searches for treasure at a depth of 20.0m below the surface of the sea. at what pressure must the scuba device deliver air to the diver? (density of sea water= 1030kg/m^3;atmospheric pressure= 1.013x10^5 pa)
May 6, 2012

Calculus
(-1)^1/4^1*1 + (-1)^2/4^2*2 + (-1)^3/4^3*3 + (-1)^4/4^4*4 + (-1)^5/4^5*5 + (-1)^6/4^6*6
May 6, 2012

Calculus
The answer I got was 0.9336. I did
May 6, 2012

Calculus
Approximate the sum of the series correct to four decimal places. n=1 to infinity (-1)^n/4^n*n!
May 6, 2012

psychology
the term "insanity" is used
May 5, 2012

CHEMISTRY
A 22.2-g piece of Al (which has a molar heat capacity of 24.03 J/mol°C) is heated to 84.6°C and dropped into a calorimeter containing water (the specific heat capacity of water is 4.18 J/g°C) initially at 23.5°C. The final temperature of the water is 27.8°C...
May 1, 2012

CEMISTRY
Consider a weak acid HX. If a 0.10 M solution of HX has a pH of 5.87 at 25°C, what is ΔG° for the acid's dissociation reaction at 25°C?
May 1, 2012

chemistry
T = 765 K, PN2 = 31 atm, PH2 = 182 atm, PNH3 = 15 atm
May 1, 2012

chemistry
Calculate ΔG for this reaction under the following conditions (assume an uncertainty of ±1 in all quantities). Assume that ΔH° and ΔS° do not depend on temperature.
May 1, 2012

Math /Algebra
Equation: y=mx+b If m= slope b= y-intercept what is x and y??? I doubt I worded this in a way that makes sense but I need help.
May 1, 2012

statistics
: an airline offers discounted advanced purchase fares to customers who buy tickets more than 30 days before travel and charges regular fares for tickets purchased in the last 30 days before travel. The airline notices 60% of its customers take advantage of the advanced ...
May 1, 2012

CHEMISTRY
The enthalpy of neutralization for the reaction of a strong acid with a strong base is −56 kJ/mol of water produced. How much energy will be released when 198.5 mL of 0.400 M HCl is mixed with 150.1 mL of 0.500 M NaOH?
May 1, 2012

CHEMISTRY
Consider the following cyclic process carried out in two steps on a gas. Step 1: 41. J of heat is added to the gas, and 20. J of expansion work is performed. Step 2: 60. J of heat is removed from the gas as the gas is compressed back to the initial state. Calculate the work ...
April 30, 2012

CHEMISTRY
In a coffee cup calorimeter 70.0 mL of 0.100 M AgNO3 and 70.0 mL of 0.100 M HCl are mixed to yield the following reaction. Ag+(aq) + Cl ‾(aq) → AgCl(s) If the two solutions are initially at 22.60°C, and if the final temperature is 23.39°C, calculate ΔH...
April 30, 2012

social studies
Different labor systems and cultures predominated in various regions of British America. How did the economy of each region help determine its labor systems and customs?
April 30, 2012

Physics
The mass of a rocket car plus fuel is 2,000kg. The rocket car starts from rest. The engine expels fuel(in the form of exhaust) over a period of 8 seconds. The exhaust has a velocity of 1,000m/s due west, and the velocity of the rocket car after 8 seconds is 90m/s due east. How...
April 30, 2012

dressmaking
Thanks for the help
April 30, 2012

dressmaking
A houndstooth(black and white plaid) jacket would work well with which of the following bodylines? A) Straight B)Soft-straight C)Soft-curved D)curved Im thinking it could be A or B.Need help for this question
April 30, 2012

Statistics
The author’s of the article “Perceived risks of Heart Disease and Cancer Among Cigarette Smokers” expressed the concern that a majority of smokers do not view themselves as being at increased risk of heart disease or cancer. Because of this, the authors call for...
April 30, 2012

Physics
a 1.5kg cannon is mounted on top of a 2.0kg cart and loaded with a 52.7 gram ball. The cannon, car, and ball are moving forward with a speed of 1.27m/s. The cannon is ignited and launches a 52.7 gram ball forward with a speed of 75m/s. Determine the post-explosion velocity of ...
April 30, 2012

Physics
The mass of a rocket car plus fuel is 2,000kg. The rocket car starts from rest. The engine expels fuel(in the form of exhaust) over a period of 8 seconds. The exhaust has a velocity of 1,000m/s due west, and the velocity of the rocket car after 8 seconds is 90m/s due east. How...
April 29, 2012

Physics
In an unusual return to space, Astronaut Sally Ride is conducting repair work on the Hubble Space telescope. She throws a hammer of mass 500.0g forward at 20.0m/s. The astronaut, mass 80.0kg, recoils in the opposite direction. What is Sally's recoil velocity?
April 29, 2012

Physics
Philadelphia Flyers player Mike Richards stands on the frictionless ice next to the goal. Neither Mike nor the goal are anchored to the ice. Frustrated after a recent playoff loss, 102.5kg Mike suddenly pushes on the goal, sending it across the ice a 2.80m/s. Mike recoils in ...
April 29, 2012

Physics
after an ice show, Michelle helps clear the props from the ice. Standing in her skates next to a potted artifical tree, she gives it a push. The tree, which has a mass of 6500g, slides forward at a velocity of 13m/s. Michelle, with a mass of 40.0kg, slides in the opposite ...
April 29, 2012

Physics
a 1.5kg cannon is mounted on top of a 2.0kg cart and loaded with a 52.7 gram ball. The cannon, car, and ball are moving forward with a speed of 1.27m/s. The cannon is ignited and launches a 52.7 gram ball forward with a speed of 75m/s. Determine the post-explosion velocity of ...
April 29, 2012

Economics
You bought the bond for \$1,040, after 6 months you received a coupon of \$35 and after another 6 months you received another \$35 coupon and you sold the bond for \$1,070. What would be your total dollar return in that case? What would be your total percentage return? Would the ...
April 29, 2012

Math
You bought the bond for \$1,040, after 6 months you received a coupon of \$35 and after another 6 months you received another \$35 coupon and you sold the bond for \$1,070. What would be your total dollar return in that case? What would be your total percentage return? Would the ...
April 28, 2012

Math-helpppppp
1)when a certain polynomial is divided by x - 3, the quotient is x^2+2x-5 and the remainder is -3. what is the polynomial 2) Find each quotient and remainder. Assume the divisor is not equal to zero. a)(2x^2+29x-x^3-40)/(-3+x) b)(6+7x-11x^2-2x^3)/(x+9) c)(x^3-2x^2+4x+150/(x^2+...
April 28, 2012

Math--help help help
1)when a certain polynomial is divided by x - 3, the quotient is x^2+2x-5 and the remainder is -3. what is the polynomial 2) Find each quotient and remainder. Assume the divisor is not equal to zero. a)(2x^2+29x-x^3-40)/(-3+x) b)(6+7x-11x^2-2x^3)/(x+9) c)(x^3-2x^2+4x+150/(x^2+...
April 28, 2012

Sociology
How would eating disorders factor into the media/cultural aspect of sociology? Would they be considered an unintentional/long term media effect?
April 26, 2012

Physics
a 65-kg ice skater moving to the right with a velocity of 2.50m/s throws a .150kg snowball to the right with a velocity of 32.0m/s relative to the ground a) what is the velocity of the ice skater after throwing the snowball? b) a second skater initially at rest with a mass of ...
April 26, 2012

Physics
a 78kg hockey player standing on frictionless ice throws a 6.0kg bowling ball horizontally with a speed of 3.0m/s. With what speed does the hockey player recoil?
April 26, 2012

Physics
a space-satellite mass of 600kg fires a rocket engine for 2 seconds expelling 40kg of exhaust gases at 350m/s. By how much will the speed of the capsule change? You may consider the initial relative velocities to be zero, but would it matter?
April 26, 2012

Physics
a 3.5kg rifle fires a 5gram bullet with a muzzle speed of 300m/s. What is the recoil speed of the rifle?
April 26, 2012

Physics
A 24-ton freight car rolls along a straight track with a speed of 10mph. A 2.0 ton automobile falling vertically lands on the freight car from above. a) what is the speed of the freight car after the car lands on it? b) the car then rolls sideways off the freight car. What is ...
April 26, 2012

Physics
a 10,000kg boxcar rolling west at 60mph collides with an empty tanker of mass 7000kg sitting at rest on the track. The cars attach and continue to roll west on the track. What is the speed of the connected cars?
April 26, 2012

Physics
a diatomic molecule of oxygen traveling at 330m/s collides head on with a carbon dioxide molecule going 270m/s. The oxygen molecule bounces off the carbon dioxide molecule in the opposite direction going 365m/s. What is the speed and direction of the carbon dioxide molecule? (...
April 26, 2012

Physics
two carts with masses of 10.0kg and 2.5kg move in opposite directions on a frictionless track, with speeds of 6.0m/s and 3.0m/s respectively. The carts stick together after colliding head on. Find the final speed of the two cars
April 26, 2012

Physics
A 5-gram bullet going 200m/s hits a 40-gram "tin can" resting on a fence post. The bullet passes through the can emerging with a speed of 160m/s in the same direction. How fast, in the same direction, does the can go after the bullet has passed through.
April 26, 2012

geomitry
what measure is formed by the hands of a clock at 5:00
April 26, 2012

psychology
How is the experience of emotion related to engaging in health-promoting behaviors such as exercising and recreational sports? a) Negative emotion increases health-promoting behaviors. b) Positive emotion increases health-promoting behaviors c) Positive and negative emotions ...
April 26, 2012

English
In the sentence The trainer, armed with a whip, entered the cage. I think I have it right, but am not sure. I have entered as the participle, armed with a whip as the modifier and no object of the participle. Is this correct?
April 26, 2012

Physics
1. volume 2. I don't know 3. Euclidean Space
April 24, 2012

Physics
A(n) 0.187 kg baseball is thrown with a speed of 29 m/s. It is hit straight back at the pitcher with a final speed of 22.3 m/s. What is the magnitude of the impulse delivered to the ball? Answer in units of kg · m/s
April 23, 2012

Biology
What does follicular activity mean?
April 23, 2012

mosinee
First you take 1,009.88 and subtract 130. that'll give you 879.88. then you add 6.19to that number and there's your answer
April 23, 2012

Biology
I am analyzing a scientific article for my biology class. I am trying to comprehend all of the terms used and am hoping I can gain other's insight as to where this article is flawed and what could have been done to improve it. The article is titled: Effect of age and ...
April 23, 2012

chemistry
The molal boiling point constant (Kb) for water is ).51oC/m and the molal freezing point constant (Kf) for water is 1.86oC/m. Given this information here is the question... If I pour 25 mL of 0.035 M NaOH into 975 mL of water, what is the new concentration of NaOH?
April 19, 2012

Chemistry
At 50 degrees, 100 grams of water is saturated with cerium (III) sulfate. How many grams of cerium (III) sulfate must be added to saturate the solution at zero degrees celsius?
April 18, 2012

Chemistry
If 30 grams of KCl is dissolved in 100 grams of water at 40 degrees celsius, how many additional grams of KCl would be needed to make the solution saturated at 80 degrees celsius?
April 18, 2012

CHEMISTRY
A student calibrates his/her calorimeter. S/he performs part 1 as instructed. The data are: 99.2 g water at 36.0°C are added to 97.3 g water in the calorimeter at 16.0°C. The final temperature is 26.0°C. Calculate the heat capacity of the calorimeter in J/°C.
April 17, 2012

biology
how can you identify gasses released by plants and animals
April 17, 2012

Math
If i had a 65% in a course now, and i need a 70% to pass, What will i need to get on my final exam worth 25% to pass the course?
April 17, 2012

CHEMISTRY
A student calibrates his/her calorimeter. S/he performs part 1 as instructed. The data are: 99.2 g water at 36.0°C are added to 97.3 g water in the calorimeter at 16.0°C. The final temperature is 26.0°C. Calculate the heat capacity of the calorimeter in J/°C.
April 16, 2012

CHEMISTRY
Suppose 1400 J of heat energy are put into a sample of liquid water at 23°C, and the final temperature of the water is 78°C. How many grams of water are present?
April 16, 2012

Math
If i had a 65% in a course now, and i need a 70% to pass, What will i need to get on my final exam worth 25% to pass the course?
April 16, 2012

Chemistry
If the literature value for the ΔHfus of water is 6.01 kJ/mol, how many kJ of heat energy would be required to completely melt 130 g of ice at 0°C?
April 16, 2012

physics
oh you meant in the question, sorry they didn't copy over!
April 16, 2012

physics
what units were missing? I see units on all my numbers. I found it though, I just had to divide my radius in half... although I do not know why!
April 16, 2012

physics
If a 80 lightbulb emits 4.0 of the input energy as visible light (average wavelength 550 ) uniformly in all directions, estimate how many photons per second of visible light will strike the pupil (4.0 diameter) of the eye of an observer 3.0 away. 1. I found the energy of ...
April 16, 2012

us history
what was James L. Farmer, Jr. political and religious views?
April 13, 2012

math
wtf none of your beess wax
April 12, 2012

math
A map has a scale of 1/2 inch to 4 miles. The shortest distance between two cities on the map measures 8 inches. If d represents the shortest distance between the two cities, what is d?
April 11, 2012

physics!
The far point of a nearsighted person is 5.8 m from her eyes, and she wears contacts that enable her to see distant objects clearly. A tree is 18.7 m away and 1.8 m high. (a) When she looks through the contacts at the tree, what is its image distance? (b) How high is the image...
April 10, 2012

Math
A bag of marbles contains 5 red, 12 blue and 5 yellow. What is the ratio of red marbles to non red marbles?
April 9, 2012

Finance
Jungle, Inc. has a target debt-equity ratio of 0.72. Its WACC is 11.5 percent and the tax rate is 34 percent. What is the cost of equity if the aftertax cost of debt is 5.5 percent?
April 9, 2012

kinesiology
what joint does splenius muscle cross?
April 5, 2012

psychology
What is concepts of reliability and validity as they pertain to psychological testing? I have a test comming up and I am confused by the concepts of reliability and validity as they pertrain to psychological testing. Can someone explain this to me? thank you!
April 5, 2012

psychology
Mike waits until the night before his big exam to start studying. He maintains that last minute cramming keeps the information fresh in his memory. What does connectionist network research tell us about the effectiveness of cramming? a)It is very effective because the ...
April 4, 2012

Physics
An alpha particle, initially moving at a speed of 7.10x10^5m/s, goes through a potential difference of 2500V. Determine the final speed of the alpha particle. Answer: 8.64 x 10^5
April 3, 2012

Physics
The sound from a mosquito is produced when it beats its wings at the average rate of 559 wing beats per second. What is the wavelength of the sound?
April 2, 2012

Ap chem
When 80.4 moles of calcium acetate are dissolved in enough water to make 222.2 milliliters of solution, what is the molarity of acetate ions? Answer in units of M I already tried moles/liter and it was wrong
April 1, 2012

World History
Why were the cash economies introduced by the Europeans unsuitable for African countries?
March 30, 2012

physics
A bullet of mass 12.4 g is fired into an initially stationary block and comes to rest in the block. The block, of mass 1.02 kg, is subject to no horizontal external forces during the collision with the bullet. After the collision, the block is observed to move at a speed of 4....
March 29, 2012

geometry
a person is standing 12m away from a street light that is 9m tall. How tall is he if his shadow is 3m long?
March 29, 2012

physics
The electromagnetic wave that delivers a cellular phone call to a car has a magnetic field with an rms value of 1.90 10-10 T. The wave passes perpendicularly through an open window, the area of which is 0.20 m2. How much energy does this wave carry through the window during a ...
March 26, 2012

physics
An electromagnetic wave in a vacuum has a magnetic field with a magnitude of 1.7 x 10^-6 T. What is the intensity S of the wave?
March 26, 2012

Physics help!
Suppose that a police car on the highway is moving to the right at 26 m/s, while a speeder is coming up from almost directly behind at a speed of 37 m/s, both speeds being with respect to the ground. The police officer aims a radar gun at the speeder. Assume that the ...
March 26, 2012

child psychology
Mishel's research shows that --------- is especially important in teaching children to delay gratification and resit temptation. A. the desire-theory of mind B.diverting attention C.perspective taking D.reinforcing I think its C, am I correct please help
March 26, 2012

child psychology
what is the only emotion that males express freely than females in every day interaction A.anger B.Sorrow C.Embarrassment D.Envy I think it is A but not sure because at time girls are the more aggresive ones. please help
March 26, 2012

child psychology
Parents of impulsive children can foster conscience development by building a a warm affectionate relationship the promotes A. secure attachment B.ego development I stongly believe its A please help
March 26, 2012

child psychology
Typically when paired with a boy in a laboratory play session, a two year old girl is likely to A. stand idly while the boy explores the toy B.assume domineering behavior, telling him what to do C.actively explore the surroundings D.play cooperatively with the boy I think its ...
March 26, 2012

child psychology
A parent who uses imperitives and specifit suggestions in everyday life is most likely the parent of A.son B.daughter C.teenager D.son and a daughter I think its C but not sure because teenagers dont have time to listen
March 26, 2012

child psychology
I still need help with this question Which young adult is at risk of long term identity foreclosure or diffusion? A. A college graduate who switces majors B. An aspiring chef who has no opportunity for culinary training. C.A young woman with several possible vocational choices...
March 25, 2012

child psychology
Do you suggest it is A Thanks
March 25, 2012

child psychology
Dean associates certain activites,roles, and traits as being typical for either males or females.His associations conform to cultural stereotypes and encompass many gender-linked responses.This is an example of gender: A.atypicality B.roles C.typing D.identity I think its B or...
March 25, 2012

child psychology
I strongly believe it is A
March 25, 2012

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