Thursday

May 28, 2015

May 28, 2015

Total # Posts: 392

**probability**

2. mean 50, variance 25
*April 11, 2015*

**PHYSICS**

In a power plant the high pressure turbine trips due to an unauthorised valve shutdown. What are a) what is the angular acceleration of the turbine blade? b) what is the distance travelled by a point on the rim of the turbine blade during the acceleration? c) what is the ...
*April 8, 2015*

**Math**

The inverse of a 2x2 matrix is given by: A=[a b A^1=1/ad-bc[d -b c d]. -c a]. If these two multiplied by each other gives the "identity matrix": [1 0 0 1]. then the inverse exists.
*April 8, 2015*

**math**

x=number of mystery books. 3x=total number of books on the shelf. x/5<10<x/4 is given. Get rid of the fifths and quarters by multiplying by 20. 4x<200<5x --> 40<x<50. The number of mystery books is anything between 40 and 50, multiply by 3 and you have ...
*April 8, 2015*

**PHYSICS**

A dock worker is loading a 25 kg solid cylindrical barrel to a ship by rolling it up a 9 meter long and 1.5 meter high ramp. At the top of the ramp the dock worker stop to go around the barrel but he loses the grip and the barrel starts to roll down the ramp without slipping ...
*April 8, 2015*

**Algebra**

x=4 gives inclination=k=1 in y=kx+m. It also states that m=4. y=x+4
*April 8, 2015*

**PHYSICS**

273.15°K is 0°C. Go from there to 232°C and its where tin melts. Conversion from °C to °K °K = °C + 273.15
*April 8, 2015*

**chemisty**

The initial concentration of NO2 in a closed container is 0.750M. At equilibrium the concentration of O2 is 0.125M. What are the concentrations of NO2 and NO at equilibrium? 2NO2 (aq) ==== 2NO (aq) + O2 (aq)
*March 1, 2015*

**chemistry**

The equilibrium concentration of NOCl = {0.0610}, NO = [0.0151, and Cl= [0.0142, what is the value of the equilibrium constant? Don't really get how to figure this out..anyone know? Thanks!!
*March 1, 2015*

**chemistry**

The density of acetonitrile, CH3CN, is 0.786 g/mL, and the density of methanol, CH3OH, is 0.791 g/mL. A solution is made by dissolving 15.0 g of methanol in 250.0 mL of acetonitrile. Assuming that the volumes of the solute and solvent are additive, what is the molarity of ...
*February 5, 2015*

**chemistry**

The Henry's law constant for CO2 is 3.1 x 10-2 mol/L-atm at 25°C. What pressure would be necessary in order to have a .25 M solution?
*February 5, 2015*

**chemistry**

The Henry’s Law constant for N2 in water at 30 oC is 6.0 x 10-4 M/atm, calculate the solubility of nitrogen gas in water at a partial pressure of 2.5 atm
*February 5, 2015*

**physics**

One particle has a mass of 2.86 x 10-3 kg and a charge of +7.32 μC. A second particle has a mass of 6.41 x 10-3 kg and the same charge. The two particles are initially held in place and then released. The particles fly apart, and when the separation between them is 0.127 ...
*January 24, 2015*

**physics **

A particle of charge +18.1C and mass 7.06 × 10-5 kg is released from rest in a region where there is a constant electric field of +414 N/C. What is the displacement of the particle after a time of 3.06 × 10-2 s? Please explain the steps, thank you.
*January 19, 2015*

**physics **

Two geological field teams are working in a remote area. A global positioning system (GPS) tracker at their base camp shows the location of the first team as 43 km away, 23° north of west, and the second team as 29 km away, 33° east of north. When the first team uses ...
*January 15, 2015*

**lauric acid **

what happens to the calculated molar has if the lauric acid is spilled before determining the freezing point?
*January 8, 2015*

**Algebra 2**

3.4e^2-2n - 9 = -4
*December 11, 2014*

**physics **

Due to a tune-up, the efficiency of an automobile engine increases by 4.00%. For an input heat of 1530 J, how much more work does the engine produce after the tune-up than before?
*December 4, 2014*

**physics **

The internal energy of a system changes because the system gains 180 J of heat and performs 338 J of work. In returning to its initial state, the system loses 111 J of heat. During this return process, what work is involved? If the work is done by the system, then give the ...
*December 3, 2014*

**physics Pls help **

A piece of glass has a temperature of 87.0 °C. Liquid that has a temperature of 32.0 °C is poured over the glass, completely covering it, and the temperature at equilibrium is 57.0 °C. The mass of the glass and the liquid is the same. Ignoring the container that ...
*November 22, 2014*

**Six grade percent**

plus 30 is more than half which is 25 so disregard the other way.
*November 16, 2014*

**Six grade percent**

7.5 is the answer it's 0.15*50 = 7.5
*November 16, 2014*

**math**

sorry! wrong calculation.
*November 16, 2014*

**math**

212 seata
*November 16, 2014*

**physics **

A 70.3-kg person puts on a life jacket, jumps into the water, and floats. The jacket has a volume of 3.07 x 10-2 m3 and is completely submerged under the water. The volume of the person's body that is underwater is 6.49 x 10-2 m3. What is the density of the life jacket?
*November 16, 2014*

**physics **

A copper (Young's modulus 1.1 x 1011 N/m2) cylinder and a brass (Young's modulus 9.0 x 1010 N/m2) cylinder are stacked end to end, as in the drawing. Each cylinder has a radius of 0.38 cm. A compressive force of F = 6100 N is applied to the right end of the brass ...
*November 12, 2014*

**physics**

got it, a) the stress is F/A= mg/A = 156(9.8)/7.44*10^-4= 2.05*10^6 N/m^2 B) F=S(delta y/ Lo)A,, solve for delta y delta y= (F/A)*(Lo/S) the value of F/A was found in part a, so substitute the answer in the second equation. 2.05*10^6(0.117/8.1*10^10)=2.96*10^-6m
*November 12, 2014*

**physics **

The drawing shows a 156-kg crate hanging from the end of a steel bar (S = 8.1 x 1010 N/m2). The length of the bar is 0.117 m, and its cross-sectional area is 7.44 x 10-4 m2. Neglect the weight of the bar itself and determine (a) the shear stress on the bar and (b) the vertical...
*November 12, 2014*

**Physics**

A dynamics cart with a mass of 1.70kg on a horizontal table is attached to a suspended mass of 0.40kg and released from rest. If a frictional of 2.0N opposes the motion of the cart how far does the cart travel in 1.5s
*November 9, 2014*

**physics **

A cylindrically shaped space station is rotating about the axis of the cylinder to create artificial gravity. The radius of the cylinder is 159 m. The moment of inertia of the station without people is 4.23 x 109 kg·m2. Suppose 299 people, with an average mass of 67.0 ...
*November 2, 2014*

**Physics **

A bowling ball encounters a 0.760-m vertical rise on the way back to the ball rack, as the drawing illustrates. Ignore frictional losses and assume that the mass of the ball is distributed uniformly. The translational speed of the ball is 7.83 m/s at the bottom of the rise. ...
*November 2, 2014*

**physics **

A man holds a 185-N ball in his hand, with the forearm horizontal (see the figure). He can support the ball in this position because of the flexor muscle force , which is applied perpendicular to the forearm. The forearm weighs 24.3 N and has a center of gravity as indicated. ...
*October 28, 2014*

**Physics **

The wheels, axle, and handles of a wheelbarrow weigh W = 57 N. The load chamber and its contents weigh WL = 674 N. The drawing shows these two forces in two different wheelbarrow designs. To support the wheelbarrow in equilibrium, the man’s hands apply a force to the ...
*October 27, 2014*

**Physics**

A beam of particles is directed at a 0.017-kg tumor. There are 2.4 x 1010 particles per second reaching the tumor, and the energy of each particle is 5.2 MeV. The RBE for the radiation is 14. Find the biologically equivalent dose given to the tumor in 27 s.
*October 27, 2014*

**Physics , Pls help**

A space station consists of two donut-shaped living chambers, A and B, that have the radii shown in the figure. As the station rotates, an astronaut in chamber A is moved 2.06 x 102 m along a circular arc. How far along a circular arc is an astronaut in chamber B moved during ...
*October 25, 2014*

**physcs **

Two newly discovered planets follow circular orbits around a star in a distant part of the galaxy. The orbital speeds of the planets are determined to be 41.8 km/s and 64.6 km/s. The slower planet's orbital period is 8.84 years. (a) What is the mass of the star? (b) What ...
*October 21, 2014*

**guidance**

yes, it is B
*October 20, 2014*

**guidance**

it is aggression, you can't kick others, take it from that principle.
*October 20, 2014*

**Physics**

Got it: reasoning and solution.. the normal force exerted by the wall on each astronaut is the centripetal force needed to keep him in the circular path so, Fc=mv^2/r. rearranging and letting Fc=(1/3)mg yields r=3v^2/g= 3(29.1m/s)^2/(9.8m/s^2)=259m
*October 20, 2014*

**Physics **

Suppose the surface (radius = r) of a cylindrical space station is rotating at 29.1 m/s to provide artificial gravity. What must be the value of r for the astronauts to weigh 1/3 of their earth weight? Don't know how to start please help.
*October 20, 2014*

**physics**

I was able to solve this problem at firs, use the equation V=sqrt(R g tan theta) since you have two angles you will need to separate the equation into 2 Va= sqrt(r g tan a theta) Vb= sqrt (r g tan b theta) then solve for Vb Vb/Va= sqrt(r g tanb )/ sqrt(r g tan a theta) r and g...
*October 20, 2014*

**physics **

Curve A is banked at 11.2 °, and curve B is banked at an angle of 15.2 °. A car can travel around curve A without relying on friction at a speed of 14.5 m/s. At what speed can this car travel around curve B without relying on friction? Do I need to find radius in ...
*October 20, 2014*

**physics**

Thank you Don. A great way of clarifying through the steps, very detail oriented. Thanks again!
*October 20, 2014*

**physics **

Car A uses tires for which the coefficient of static friction is 0.333 on a particular unbanked curve. The maximum speed at which the car can negotiate this curve is 13.8 m/s. Car B uses tires for which the coefficient of static friction is 0.843 on the same curve. What is the...
*October 20, 2014*

**physics**

Thanks a lot Damon!
*October 12, 2014*

**physics **

A ball is dropped from rest at the top of a 5.89-m-tall building, falls straight downward, collides inelastically with the ground, and bounces back. The ball loses 5.34% of its kinetic energy every time it collides with the ground. How many bounces can the ball make and still ...
*October 12, 2014*

**CHEMISTRY**

As far as I know, Delta T means the difference in temperature. T final- T initial.
*October 12, 2014*

**physics**

ok I got the answer: a) Vf1=(m1-m2/m1+m2)*(Vi1) B) Vf2=[(2(m1)/m1+m2](Vi1)
*October 12, 2014*

**physics**

sorry I solved part C, I need help with a and b pls.
*October 12, 2014*

**physics**

A 2.20-kg ball, moving to the right at a velocity of +1.27 m/s on a frictionless table, collides head-on with a stationary 7.20-kg ball. Find the final velocities of (a) the 2.20-kg ball and of (b) the 7.20-kg ball if the collision is elastic. (c) Find the magnitude and ...
*October 12, 2014*

**physics **

A 220-kg log is pulled up a ramp by means of a rope that is parallel to the surface of the ramp. The ramp is inclined at 26.6° with respect to the horizontal. The coefficient of kinetic friction between the log and the ramp is 0.863, and the log has an acceleration of 0....
*October 1, 2014*

**physics**

I figured this out.. So basically you find the acceleration first V-Vo/t= 59.4-0/14.1 = 4.21m/s2 then, you find the apparent weight by multiplying 66.7*(9.8 + 4.21)= 934.47N
*September 30, 2014*

**physics**

A rocket blasts off from rest and attains a speed of 59.4 m/s in 14.1 s. An astronaut has a mass of 66.7 kg. What is the astronaut's apparent weight during takeoff?
*September 30, 2014*

**Math**

and theta is between 0< theta< 2 pi
*September 29, 2014*

**Math**

solve: cot(2theta/3)= -sqrt3 Please help, I don't know how to start and how to set it up.
*September 29, 2014*

**physics**

A rocket blasts off from rest and attains a speed of 59.4 m/s in 14.1 s. An astronaut has a mass of 66.7 kg. What is the astronaut's apparent weight during takeoff?
*September 28, 2014*

**physics**

Damon, I honestly want to thank you for your precious efforts in helping students. I have a question regarding the equations you've set above. Could you clarify how to find FB please?
*September 27, 2014*

**physics**

The mass of a robot is 6930 kg. This robot weighs 2520 N more on planet A than it does on planet B. Both planets have the same radius of 3.01 × 106 m. What is the difference MA - MB in the masses of these planets?
*September 27, 2014*

**physics**

A ball is thrown upward at a speed v0 at an angle of 59.0¢ª above the horizontal. It reaches a maximum height of 7.5 m. How high would this ball go if it were thrown straight upward at speed v0?
*September 20, 2014*

**physics**

thank you very much Damon. It is much clear now, since u explained it step by step.
*September 19, 2014*

**physics**

An airplane with a speed of 85.3 m/s is climbing upward at an angle of 45.0 ° with respect to the horizontal. When the plane's altitude is 587 m, the pilot releases a package. (a) Calculate the distance along the ground, measured from a point directly beneath the point...
*September 19, 2014*

**physics- HELP**

An airplane with a speed of 85.3 m/s is climbing upward at an angle of 45.0 ° with respect to the horizontal. When the plane's altitude is 587 m, the pilot releases a package. (a) Calculate the distance along the ground, measured from a point directly beneath the point...
*September 19, 2014*

**physics**

An Olympic long jumper leaves the ground at an angle of 18.7 ° and travels through the air for a horizontal distance of 7.04 m before landing. What is the takeoff speed of the jumper?
*September 19, 2014*

**physics**

An airplane with a speed of 85.3 m/s is climbing upward at an angle of 45.0 ° with respect to the horizontal. When the plane's altitude is 587 m, the pilot releases a package. (a) Calculate the distance along the ground, measured from a point directly beneath the point...
*September 19, 2014*

**physics**

A tennis ball is struck and departs from the racket horizontally with a speed of 26.4 m/s. The ball hits the court at a horizontal distance of 18.4 from the racket. How far above the court is the tennis ball when it leaves the racket?
*September 15, 2014*

**Math**

Lola is placing appetizers on plates She has 63 spring rolls and 84 cheese cubes She wants to include both appetizers on each plate Each plate must have the same number of spring rolls and cheese cubes. What is the greatest number of plates she can make using all of the ...
*September 15, 2014*

**physics**

A tennis ball is struck and departs from the racket horizontally with a speed of 26.4 m/s. The ball hits the court at a horizontal distance of 18.4 from the racket. How far above the court is the tennis ball when it leaves the racket?
*September 15, 2014*

**physics**

A tennis ball is shot vertically upward in an evacuated chamber inside a tower with an initial speed of 20.0 m/s at time t = 0 s. Approximately how long does it take the tennis ball to reach its maximum height?
*September 13, 2014*

**physics **

The depth of the ocean is sometimes measured in fathoms (1 fathom = 6 feet). Distance on the surface of the ocean is sometimes measured in nautical miles (1 nautical mile = 6076 feet). The water beneath a surface rectangle 3.70 nautical miles by 2.80 nautical miles has a depth...
*September 13, 2014*

**physics**

The depth of the ocean is sometimes measured in fathoms (1 fathom = 6 feet). Distance on the surface of the ocean is sometimes measured in nautical miles (1 nautical mile = 6076 feet). The water beneath a surface rectangle 3.70 nautical miles by 2.80 nautical miles has a depth...
*September 13, 2014*

**physics **

The depth of the ocean is sometimes measured in fathoms (1 fathom = 6 feet). Distance on the surface of the ocean is sometimes measured in nautical miles (1 nautical mile = 6076 feet). The water beneath a surface rectangle 3.70 nautical miles by 2.80 nautical miles has a depth...
*September 13, 2014*

**chem**

Thank you Dr. Bob
*September 11, 2014*

**chem**

If 309 J of heat are removed from 10.0 g of ice (specific heat = 2.06 J/g ºC) at -5.5 ºC, what is the final temperature of the ice sample?
*September 11, 2014*

**physics**

A car is traveling along a straight road at a velocity of +27.7 m/s when its engine cuts out. For the next 1.94 seconds, the car slows down, and its average acceleration is . For the next 4.92 seconds, the car slows down further, and its average acceleration is . The velocity ...
*September 9, 2014*

**physics**

A race driver has made a pit stop to refuel. After refueling, he starts from rest and leaves the pit area with an acceleration whose magnitude is 5.4 m/s2; after 4.4 s he enters the main speedway. At the same instant, another car on the speedway and traveling at a constant ...
*September 7, 2014*

**physics**

Two rockets are flying in the same direction and are side by side at the instant their retrorockets fire. Rocket A has an initial velocity of +4100 m/s, while rocket B has an initial velocity of +9400 m/s. After a time t both rockets are again side by side, the displacement of...
*September 7, 2014*

**physics**

thanks Demon
*September 7, 2014*

**physics**

In getting ready to slam-dunk the ball, a basketball player starts from rest and sprints to a speed of 11.0 m/s in 2.58 s. Assuming that the player accelerates uniformly, determine the distance he runs.
*September 7, 2014*

**Algebra 2**

4t-3s^2+s^3 for t=-2 and s=-3 4(-2)-3(-3)^2+(-3)^3 -8-3(-9)+(-27) -8-(-27)+(-27)=-8 Am I right?
*September 3, 2014*

**Probability**

In a random sample of students at a middle school, 24 wanted to change the mascot, and 30 wanted to keep the current mascot. Which is the best prediction for how many of the total of 1,140 students want to keep the current mascot? (a) 507 (b) 600 (c) 633 (d) 950
*July 24, 2014*

**Chemistry **

Benzene sulfonic acid, C6H5SO3H, is a strong acid and will neutralise sodium hydroxide solution (a 1:1 molar ratio). Benzene sulfonic acid crystals (y grams) were weighed into a titration flask and titrated against sodium hydroxide solution (1.0 M) and needed a volume of 26.2 ...
*June 15, 2014*

**Maths**

1. What is the Right Riemann Sum for f(x)=x−3 over the interval [8,11], with n=3 rectangles of equal width? 2. What is the right Riemann sum of f(x)=x+3 when using 3 rectangles in the range [−3,−1]? 3. What is the left Riemann sum of f(x)=−2x+1 when ...
*June 1, 2014*

**Math**

A rectangular rug has a base b and a height h, with a perimeter of 30 feet. Both b and h are both whole numbers between 5 and 10 feet. Fill in the blanks to complete this sentence: The area of the rug is at least _______ but not greater than ______.
*May 29, 2014*

**statistics**

Phil is right, the answer is B
*April 27, 2014*

**business Math**

Rate= interest / principal*time interest = 15 Principal =100 Time is 2/52 (2 weeks/ 52 weeks/year) 15/(100*2/52)= 3.90 3.90*100 = 390%
*April 2, 2014*

**physics**

a glass lens has a convex surface with a radius 25.0 cm and a concave surface with radius 50.0 cm with the glass refraction = 1.51 calculate the focal length
*March 30, 2014*

**Help!! Physics**

What capacitance in needed in series with an 785 µH inductor to form a circuit that radiates a wavelength of 199 m?
*March 29, 2014*

**English/Social Studies**

I have checked some of these sites and while it gives me the pros and cons, I don't see a reason why or how implementing this program will affect us economically?
*March 26, 2014*

**English/Social Studies**

I'm writing an essay and need help coming up with economic reasons to to be against Caps on Punitive Damages. Google is not turning up what I need. I need how will implementing this program be bad economically?
*March 26, 2014*

**Calculus**

Find the limit. lim 5-x/(x^2-25) x-->5 Here is the work I have so far: lim 5-x/(x^2-25) = lim 5-x/(x-5)(x+5) x-->5 x-->5 lim (1/x+5) = lim 1/10 x-->5 x-->5 I just wanted to double check with someone and see if the answer is supposed to be positive or negative. ...
*January 22, 2014*

**CIVICS!!!**

dw2q
*January 20, 2014*

**Calculus**

What is the domain of f(x)= (x-3)/(x^2-9)? lim f(x) x->3
*January 18, 2014*

**Language Arts**

Oh okay I get it now. Thank you. :)
*January 14, 2014*

**Language Arts**

Thank you I also was wondering about my answer for this question. *Climbing so slowly they seem immobile* is how sloths spend their days. A. Prepositional Phrase B. Gerund Phrase C. Participial Phrase D. Appositive Phrase My answer is A. Am not sure if it's right or not.
*January 14, 2014*

**Language Arts**

*Trying to laugh as quietly as possible*, Lucas snuck out of the kitchen. A. Prepositional phrase B. Gerund phrase C. Participial phrase D. Appositive phrase Hello I was wondering if my answer is correct for this question, the answer I choose was C. Thanks. :)
*January 14, 2014*

**math**

well aren't you helpful h.
*December 8, 2013*

**Biochem**

Should say absorbancy *, A, was plotted.. My phone autocorrected the word.
*December 6, 2013*

**Biochem **

If the calibration curve for a Beer's Law plot of a protein assay had a slope of 0.433 when absorb acne, A, was plotted as a function of protein concentration, c, in mg/mL. The absorbance of an unknown protein sample was 0.345. What is the concentration of protein in this ...
*December 6, 2013*

**Chem**

If the calibration curve for a Beer's Law plot of a protein assay had a slope of 0.433 when absorb acne, A, was plotted as a function of protein concentration, c, in mg/mL. The absorbance of an unknown protein sample was 0.345. What is the concentration of protein in this ...
*December 6, 2013*

**Science**

A biologist is constructing a cladogram to show the evolutionary relationships between the animals shown below. If anatomical features are used to construct the cladogram, which animal will be placed farthest from the shown animal? Animal shown: connexus. com/content/media/...
*December 5, 2013*