Monday
September 22, 2014

Posts by tim


Total # Posts: 952

chemistry
A 25.00 mL solution of potassium nitrate (KNO3) was diluted to 125.0 mL, and 25.00 mL of this solution were then diluted to 1.000 103 mL. The concentration of the final solution is 0.00421 M. Calculate the concentration of the original solution.
October 1, 2012

Physics
A man in an elevator is 79kg. The elevator itself is 860kg. As the elevator begins to move down, a scale the man is standing on reads 437N. How do I determine the acceleration of the elevator? (I tried dividing the force of the man by his mass, it was incorrect)
September 27, 2012

Grade 11 Math
Here's the question: You are attending a very loud concert. To avoid permanent ear damage, you decide to move farther from the stage. Sound intensity is given by the formula: I = k/d squared K= constant D = distance from the listener to the source of sound. Determine an ...
September 25, 2012

pre algebra
What is the rule for this pattern? 1,negative 2,4, negative 5,7,negative8. Thanks
September 23, 2012

math
Radius of a circle with a sector area of 3 square ft determined by a central angle 1/4 radian
August 27, 2012

math
complete the square 16x-12y=4y^2+1
August 25, 2012

Math add a bit of clarity
The * is showing a multiplication sign. The number before / is the numerator and after is the denominator. This has to do with proportions and cross products but I am not understanding the rules/principles here.
August 25, 2012

Math
Given the formula Xc=1/6.28fC, find C if Xc =500 and f=2000. What are the rules that take me from 500/1 = 1/6.28*2000*C to the next step of: C=1*1/500*6.28*2000 ?
August 25, 2012

Calculus
Is the answer 2.25 v
August 21, 2012

Calculus
A 15.2-F capacitor has an initial voltage of 2.00 V. It is charged with a current given by i=tã5=t^2. Find the voltage across the capacitor at 1.75 seconds.
August 21, 2012

Math
I think the answer is 2.25V.
August 21, 2012

English
You've been assigned to invite a group of mechanical engineering professors to tour your facility. What type of language should you use in the invitation?
August 3, 2012

geometry
how do you find the perimeter of a triangle, longest side is 48cm, line down the middle is 8 and the sides are both 10.
July 25, 2012

Math Gr12 (advanced functions)
A tower that is 65m high makes an obtuse angle with the ground. The vertical distance from the top of the tower to the ground is 59m. What obtuse angle does the tower make with the ground?
July 16, 2012

Chemistry
Sorry, if I wasn't very clear. I've tried both acid and HCl for the 1st blank and borax and base for the 2nd blank, but still wrong. end point is right though!
July 5, 2012

Chemistry
This is a lab called Enthalpy and Entropy of Borax Dissolution and I just can't seem to get the right answers... Please help me fill in the blanks The _____ (acid/HCl?)is placed in the buret and the ____ (base/borax?) is placed in the flask beneath the buret. For this ...
July 5, 2012

Physics
which has the greater average speed: a car that travels from milepost 35 to milepost 40 in 5 minutes, or one that travels from milepost 68 to milepost 78 in 10 minutes?
July 1, 2012

algebra
Bob had three 10' lengths of conduit. If he used a total of 13.75' of conduit to install a motor, how much total conduit does he have left?
June 28, 2012

physics
A comet orbits the Sun with a period of 72.8 yr. (a) Find the semimajor axis of the orbit of the comet in astronomical units (1 AU is equal to the semimajor axis of the Earth's orbit). (b) If the comet is 0.55 AU from the Sun at perihelion, what is its maximum distance ...
June 28, 2012

Physics
I'm supposed to get 3.21e-07 N.
June 26, 2012

Physics
A carefully designed experiment can measure the gravitational force between masses of 9 kg. Given that the density of iron is 7860 kg/m3, what is the gravitational force between two 9.00-kg iron spheres that are touching in N?
June 26, 2012

physics
I see, so that's where I messed up. Thank you once again. I get 85.3 N now.
June 22, 2012

physics
Does θ equal 0.5981 degree and W equal 1.58 m? This is what I'm doing to solve for tension: 1) 1.13T=mg(W/2)cos(θ) 2) 1.13T=(20.8)(9.81) x (1.58/2cos(0.5981)) 3) 1.13T= 1.61.1891373 4) T= 142.6452543 = 143 N Am I calculating something wrong? Am I solving for the ...
June 22, 2012

physics
Yes. However, I think I hit a wrong number on my calculator before. I still get around 142.6, though.
June 22, 2012

physics
Sorry I let my friend use my laptop and he must have typed in his into Jiskha. It's still Tim. Sorry for the confusion.
June 22, 2012

physics
I'm also confused as to why the angle θ is 0.5981. I thought I had to use arctan(1.13/141) which gives me a 38.9 degree angle.
June 22, 2012

physics
When I try balancing the forces, I end up with T = mg, which gives me an answer which is over twice the correct answer.
June 22, 2012

physics
A trapdoor on a stage has a mass of 20.8 kg and a width of 1.58 m (hinge side to handle side). The door can be treated as having uniform thickness and density. A small handle on the door is 1.41 m away from the hinge side. A rope is tied to the handle and used to raise the ...
June 22, 2012

Physics
I was able to figure this one out with a related question. Thank you!
June 19, 2012

Physics
A thin uniform rod (length = 1.3 m, mass = 3.2 kg) is pivoted about a horizontal frictionless pin through one of its ends. The moment of inertia of the rod through this axis is (1/3)mL2. The rod is released when it is 50° below the horizontal. What is the angular ...
June 19, 2012

Trigonometry
When viewing Angel Falls (the world's highest waterfall) from Observation Platform A, located on the same level as the bottom of the waterfall, we calculate the angle of elevation to the top of the waterfall to be 69.30°. From Observation Platform B, which is located ...
June 16, 2012

Physics
A system consists of two particles. Particle 1 with mass 2.0 kg is located at (2.0 m, 6.0 m) and has a velocity of (3.1 m/s, 2.6 m/s). Particle 2 with mass 4.5 kg is located at (4.0 m, 1.0 m) and has a velocity of (1.1 m/s, 0.6 m/s). Determine the position and the velocity of ...
June 11, 2012

College Algebra
A gardener wants to fence in her plot in two equal rectangular sections. If she has 120 yards of fence and the area of the entire plot is 384 yd 2, find the possible dimensions in yards of the garden.
May 29, 2012

chemistry
determine the energy needed to cool 10 grams of H2O from 110 degrees C to -10 degrees C?
May 24, 2012

chemistry
determine the energy needed to raise the temperature of 10 grams of H2O from 25 degrees C to 75 degrees C?
May 24, 2012

UoA
356 Cal to kilowatt-hours
May 23, 2012

Chemistry 2B - UC Davis
Now calculate Kb the base dissociation constant for [C2H3O2-], acetate anion, for each of your trials from the concentrations of species at the equivalence point. Report 3 significant figures, e.g. 5.97E-10.
May 11, 2012

Physics- Final exam review
A proton with kinetic energy 100 keV is moving in a plane perpindicular to a uniform magnetic field of magnitude 2.3 T. Find the radius of its orbit. Not sure what equation to use or how to solve
April 29, 2012

Physics- Final exam help
A proton with kinetic energy 100 keV is moving in a plane perpindicular to a uniform magnetic field of magnitude 2.3 T. Find the radius of its orbit. Not sure what equation to use or how to solve.
April 29, 2012

math
two-thirds of a number, decreased by thirty-six, is at most twenty-two. Find the number.
April 25, 2012

physics
The red laser light used in supermarket scanners has a wavelength of 633 x 10-9 m. (This is 633 nanometers, 633 nm). Find the frequency of the red laser light.
April 16, 2012

Math
You have equally likely chance of choosing any number from 1 to 10. What is the probability that you choose a number greater than 6?
April 15, 2012

physical science
a hammer falls off a rooftop and strikes the ground with a certain kinetic energy. if it fell from a roof twice as tall, how would its kinetic energy compare? explain
March 29, 2012

College Physics
An electron with a speed of 1.9 × 107 m/s moves horizontally into a region where a constant vertical force of 5.4 × 10-16 N acts on it. The mass of the electron is 9.11 × 10-31 kg. Determine the vertical distance the electron is deflected during the time it ...
March 28, 2012

Maths
There are two trains. The first train is travelling at 52 km/h. The second train is travelling at 68 km/h. It takes 9 seconds for the second train to pass the first train. How long is the second train?
March 28, 2012

Biology
If nonessential amino acids are missing from the diet, can essential amino acids be substituted in the protein? I would appreciate some help with this one-thank you
March 24, 2012

biology
Traits like human height and skin color shows a wide range of phenotypes, as opposed to just two ot three. From the standpoints of genese and alleles, explain why is this so.
March 19, 2012

MATH
74.25
March 17, 2012

geometry
Two similar solids have a scale factor of 3:5. If the height of solid I is 3 cm, find the height of solid II. If the surface area of I is 54pi cm squared, find the surface area of II. If the volume of II is 250pi cubed, find the volume of I
March 13, 2012

math
85%of36145
March 9, 2012

stats
The vice-president of a business firm has reviewed the records of the finn's personnel and found that 70% of the employees read The Wall Street Journal. If the vice-president was to choose 12 employees at random,what is the probability that the number of these employees ...
March 1, 2012

Physics
A bag of blood with a density of 1050 kg/m3 is raised 1.37 m higher than the level of a patient’s arm. How much greater is the blood pressure at the patient’s arm than it would be if the bag were at the same height as the arm? Assume there is no change in drip speed ...
February 28, 2012

stats
please help How do you construct a pay of table?????? . Dr. Mike Adams, a local brain surgeon, believes there is a lot of money to be made renting apartments to students here in Alamosa. He is considering constructing one, two, or possibly three apartment complexes, each of ...
February 27, 2012

math
I want to put a 3ft wide walk around a 10ft by 15 ft pool. What is the perimeter around the figure including the path?
February 27, 2012

STATS
The vice-president of a business firm has reviewed the records of the firm's personnel and found that 70% of the employees read The Wall Street Journal. If the vice president was to choose 12 employees at random, what is the probability that the number of these employees ...
February 27, 2012

stats
. Each week during the first half of the semester, a sample of 50 students was polled to determine how many of them had their homework done before class. The following arc the results of the weekly polls: Week # # of students with homework done 1 1 2 8 3 12 4 14 5 22 6 30 7 25...
February 26, 2012

stats
20. The sponsor of a local soccer tournament is responsible for writing an article for the local paper announcing the 151, 2nd, and3rdplacewinners. If10teamsareinvitedtothe tournament, and the sponsor wanted to get the article written in advance so it can go out in the next ...
February 26, 2012

statistics
12. A statistics student received a grade of 85 on a statistics midterm. If the corresponding z score equaled +1.50, and the standard deviation equaled 7, what was the average grade on this exam? a. 95.5 b. 74.5 c. 78.0 d. Cannot determine without knowing how many took the ...
February 26, 2012

stats
if one can choose any six of 40 numbers, in any order, to play a state lottery game, how many different arrangments are possible?
February 26, 2012

physics
A pitched ball is hit by a batter at a 45° angle and just clears the outfield fence, 90 m away. Assume that the fence is at the same height as the pitch and find the velocity of the ball when it left the bat. Neglect air resistance.
February 25, 2012

physics
A ball rolls with a speed of 6.4 m/s toward the edge of a table that is 0.7 m above the floor. The ball rolls off the table. a. Find the magnitude of the balls velocity when it hits the floor. m/s b. At what angle, measured from the horizontal, will the ball's velocity ...
February 25, 2012

Physics resistance question
No drop
February 21, 2012

stats
The sponosor of a local soccer tournament is responsible for writting an article for the local paper announcing the 1st, 2nd, 3rd place winners.If 10 teamsare invited to the tournament, ans th sponsor wanted to get the article written in adance so it can go out in the next ...
February 20, 2012

trig
The minute hand of a clock is 6 inches long. What distance does its tip move in 16 minutes?
February 20, 2012

psychology
what are some movies that is related to the issues of child development and developmental psychology
February 20, 2012

psychology
What are some movies that is related to the issues of child development and developmental psychology
February 19, 2012

Physics
The driver of a truck slams on the brakes when he sees a tree blocking the road. The truck slows down uniformly with acceleration −5.15 m/s2 for 4.20 s, making skid marks 62.1 m long that end at the tree. With what speed does the truck then strike the tree?
February 7, 2012

Mathamatics 101
An angle is 35 degrees more than 4 times its supplementary angle. Find the measures of the two angles.
February 5, 2012

chemistry
how much water should i add to neutralize 1000 milliliters oh ph 13
January 31, 2012

calculus
Find area of the region under the curve y = 5 x^3 - 9 and above the x-axis, for 3¡Ü x ¡Ü 6. area = ??
January 27, 2012

math 242
It is estimated that the demand for a manufacturer's product is increasing exponentially at an instantaneous rate of 7% per year. If the current demand is increasing by 7000 units per year and if the price remains fixed at $100 per unit, how much revenue will the ...
January 27, 2012

Biology
Cells absorbing sugar or other small molecules from their surroundings is an example of A. diffusion B.osmosis C. exocytosis D.endocytosis I think it is either C or D because they both have to do with the transportation of molecules in and out of cells.
December 30, 2011

math
V = pir^2h V = pizza :)
December 29, 2011

math
The radius r of a sphere is increasing at the uniform rate of 0.3 inches per second. At the instant when the surface area S becomes 100pi square inches, what is the rate of increase, in cubic inches per second, in the volume V?
December 29, 2011

BUSS/STATS
Steve cutter sells big blade lawn mowers in his hardware store, and he is interested in comparing the reliability of the mowers he sells with the reliability of Big blade mowers sold nationwide. Steve knows that only 15 percent of all Big Blade mowers sold nationwide require ...
December 27, 2011

bio
How is it possible for an overnourished individual to be malnourished?
December 18, 2011

Calculus
Thanks again for responding. When we earlier did h=0, the formula was dh/dt=5/2pi=.8 in/min. Intuitively, it makes sense that the rate would reduce as the cup is filling up since the radius is increasing. So, should the answer above have 10 in the numerator instead of 40. Then...
December 18, 2011

Calculus
A cup has a radius of 2" at the bottom and 6" on the top. It is 10" high. 4 Minutes ago, water started pouring at 10 cubic " per minute. How fast is the water level rising now?
December 18, 2011

Calculus
In the 2nd question (rate of water rising now), how do you calculate r?
December 17, 2011

Calculus
OK, I understand now. Thanks for all of your help.
December 17, 2011

Calculus
Thanks. I think that I understand the 1st question now. How about the other questions?
December 17, 2011

Calculus
A cup has a radius of 2" at the bottom and 6" on the top. It is 10" high. 4 Minutes ago, water started pouring at 10 cubic " per minute. How fast was the water level rising 4 minutes ago? How fast is the water level rising now? What will the rate be when ...
December 17, 2011

physics
So I figured this out myself a=v^2/r which is also equal to (4pi^2*r^2)/T^2 and T is 86400 secs which is how long it takes for a day to pass
December 15, 2011

physics
How would I know W if that wasn't given?
December 15, 2011

physics
radius of the earth = 6.37 × 10^6 what is the speed of a 90.6 kg person at the equator? I know that F=m(v^2/r) but I don't know the force. Is there another equation that I'm missing or I'm using the wrong one? Thanks
December 15, 2011

physics
should be 2.24m/s use the equation F=m(v^2/r)
December 15, 2011

bio
Hi does anyone know where the following lead to/from renal artery and vein hepatic artery and vein umbilical artery and vein coronary
December 12, 2011

bio
Hi does anyone know where the following lead to/from renal artery and vein hepatic artery and vein umbilical artery and vein coronary
December 12, 2011

algebra
write an equation of the direct variation that includes the given point, (-5/6, 6/5)
December 11, 2011

article
articles either about animals or specific ecosystems
December 11, 2011

article
where can i find articles on the ecosystem ?
December 11, 2011

6th grade Science
Please help me with the questions? 1) How do you respond to some stimuli in your environment? The examples I wrote are: If I am hungry, I will eat food. If I am cold, then I will put on a jacket? 2) What does the fur of a bear have to do with homeostatis? I wrote that the fur ...
December 9, 2011

Calculus
its from 1 to 3 on the x axis including when it crosses underneath, you subtract that (its like negative area)
December 8, 2011

Calculus
Finding area under a curve From [1,3] 2x^2 -4x +1
December 8, 2011

Physics
Divers dive straight out from a cliff that is 21 m high. If the rocks below the cliff extend outward for 15 m, what is the minimum horizontal velocity a diver must have to clear the rocks safely
December 4, 2011

ochem
how to determine equivalent hyfrogens in hnmr?
December 3, 2011

chem
why do we use a weak acid or water and not a concentrated acid with NaBh4,etoh reagent?
December 2, 2011

Math
The equation y=2x+7 represents a linear relationship that is non-proportional. What changes could I make to the equation to make it proportional? Thanks
November 29, 2011

Economics
Variable cost divided by the change in quantity produced is A. average variable cost. B. marginal cost. C. average total cost. D. None of the above is correct.
November 29, 2011

pol sci
what impact is the California dream act( ab 131) going to have on us citizens or legal immigrants?
November 26, 2011

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