Total # Posts: 314
A 53.8-mg sample of sodium perchlorate contains radioactive chlorine-36 (whose atomic mass is 36.0 amu). If 29.6% of the chlorine atoms in the sample are chlorine-36 and the remainder are naturally occurring nonradioactive chlorine atoms, how many disintegrations per second ...
June 21, 2016
Two identical mass-spring systems consist of 250-g masses attached to springs of spring constant 15 N/m. If one of them starts oscillating from its equilibrium position at time t = 0, how much later should the second one start so they oscillate out of phase by 90 o?
June 9, 2016
karen has 60 percent as much as money as leslie. leslie's sum of money is 60 %mof matthews. if matthews gives karen 140, matthew will have the same money as leslie. how much do they have altogether
May 10, 2016
An airplane needs to accelerate at 4.7 m/s2 to reach take-off speed before reaching the end of the runway. The mass of the airplane is 4500 kg. How much force is needed from the engines?
January 14, 2016
Dallas Community College
A 2.00 kg blob of clay is moving with a velocity of 6.00 m/s at 49.0° when it collides and sticks to a 4.00 kg blob of clay that is moving with a velocity of 5.00 m/s at -123.0°. What is the magnitude and direction of the velocity of the resulting big blob of clay?
October 28, 2015
A bullet is found embedded in the wall of a room 2.9 m above the floor. The bullet entered the wall going upward at an angle of 36.7°. How far from the wall was the bullet fired if the gun was held 1.1 m above the floor?
October 18, 2015
Consider the equation v = (1/7)zxt2. The dimensions of the variables v, x, and t are [L/T], [L], and [T] respectively. The numerical factor 7 is dimensionless. What must be the dimensions of the variable z, such that both sides of the equation have the same dimensions?
October 16, 2015
Beaker A,B and C contain water with a total volume of 1 litre.Beaker B has 125 millilitres less water than beaker A. Beaker B has twice as much water than Beaker C.Find the volume of water in beaker B.
September 3, 2015
Bill, Would you not use: M = 2x10^30 a = 0.5 AU Giving: p = sqrt(((4*pi^2)(0.5*1.49x10^11)^3)/((6.67x10^-11)(2x10^30))) = 1.106x10^7 seconds = 0.35 years Note: Bill's verison of Kepler's 3rd Law is incorrect. Where Bill said: (4pi)^2, it should be: (2pi)^2 = 4*(pi^2)
August 14, 2015
Candice makes gift boxes during her free time.She charges 40 cents for a triangular box,50 cents for a heart shaped box and a cylindrical box for 60 cents.Last Sunday,Candice sold 16 different types of boxes and collected a total of 8 dollars.How many of each type of box did ...
July 9, 2015
She worked 40 reg hrs, 1/2 (time and a half hrs) Time and a half 1/2 hr=30 min,, at time and a half it= 3/4 or .45 min. She also worked 9 hrs at double time-- 9*2=18 reg hrs, SO.. 18+.45+40=58.45 * 13.50 = 789.075 In Gross earnings. Rounded= $789.08
June 24, 2015
Tom,Jerry and Ali share 279 marbles. Tom has 4 times as many marbles as Jerry and Ali has 36 more marbles than Tom. (a)How many marbles does Jerry have? (b)How many more marbles does Tom have than Jerry?
April 28, 2015
An architect is designing an office building with n floors that will have an FM radio antenna 15.85m tall on its roof. Each floor of the building will be 3.9m high. Which equation can be used to find the total height, h, of the building in meters, including the FM antenna? A. ...
April 9, 2015
In a deck of 52 cards, 3 cards are chosen. What is the probability that all three card are picture cards? (king, queen, jack) By the way, we are learning combinations and permutations. Help would be greatly appreciated!
March 30, 2015
In triangle ABC, points X and Z are on line AB and Y is on line AC such that line XY is parallel to line BC and line ZY is parallel to line XC. If AZ = 8 and ZX = 4, then what is XB?
March 28, 2015
The question is: Prove algebraically that the difference between the squares of any two consecutive even numbers is always a multiple of 4. My working was: Let the numbers be n and n + 2 (n+2)^2 - (n)^2 =n^2 + 4n + 4 - n^2 =4n + 4 =4(n + 1) But the answers say the numbers ...
March 5, 2015
A coffee merchant sells a customer 3 lb of Hawaiian Kona at $9.75 per pound. The merchant's scale is accurate to within ±0.03 lb. By how much could the customer have been overcharged or undercharged because of possible inaccuracy in the scale? (Round your answer to ...
February 10, 2015
Mary has $4.00 in nickels, dimes, and quarters. If she has twice as many dimes as quarters and forty-seven more nickels than dimes, how many coins of each type does she have?
February 10, 2015
A company has four production sections viz., S1, S2, S3 and S4 which contribute 30%, 20%, 28% and 22% of the total output. It was observed that those sections respectively produced 1%, 2%, 3% and 4% defective units. If a unit is selected at random and found to be defective, ...
February 4, 2015
A flat disk 1.0 m in diameter is oriented so that the plane of the disk makes an angle of pi/6 radians with a uniform electric field. if the field strength is 589.0 N/C, find the electric flux through the surface. I know that Flux=(integral)|E|cos(theta)dA but I'm not sure...
February 3, 2015
Two masses are connected by a light cord over a frictionless pulley as shown. If M1 = 8.9 kg and M2 = 5.7 kg, calculate the tension in the cable (in N). Take the coefficient of kinetic friction between M1 and the horizontal surface to be 0.3 and assume the acceleration due to ...
January 23, 2015
A charged particle is released from rest in a region that has a uniform electric field of magnitude 64.0 N/C. After traveling a distance of 0.500 m in this region, the particle has a kinetic energy of 0.880 J. The charge on the particle is _______ C
January 14, 2015
Calculate the percent purity of a sample of zinc metal if 325 mL of hydrogen gas is collected by water displacement at a temperature of 22.0 C and an atmospheric pressure of 745.0 mm Hg when 1.12 g of the sample is reacted with excess HCl: Zn + 2 HCl = H2 + ZnCl2. The vapor ...
December 11, 2014
Which of the following is a convention Chinese artist Shen Zhou used in his brush paintings? He used only black ink to emphasize expressive brushstrokes. He painted several seated Buddha in the background. He painted flat, realistic figures to reflect strength and calmness. He...
November 15, 2014
The diameter of the Moon is 3.78x10^6m. It subtends an angle of .00982 radians at the surface of Earth. How far is the Moon from Earth? (Please explain I can't wrap my head around this question.)
November 13, 2014
7th grade math
consider the inequality 2x+3≤-3. Find the set of all integer solutions of this inequality that are also solutions of the inequality 5x-2<3. Please help I am really confuded
October 22, 2014
semir, sarah and sung so decided to raise money for a local homeless shelter by working in a local deli. the deli agreed to donate to the shelter a portion of the profits from each meal the three sold. semir sold 3 times as many meals as sarah. sung sold 2 more meals than ...
October 14, 2014
A horizontal force, F1 = 85 N, and a force, F2 = 18.4 N acting at an angle of θ to the horizontal, are applied to a block of mass m = 2.1 kg. The coefficient of kinetic friction between the block and the surface is μk = 0.2. The block is moving to the right. A. Solve...
October 9, 2014
Two people decide to find the height of an obelisk. They position themselves 25 feet apart in line with, and on the same side of, the obelisk. If they find that the angles of elevation from the ground where they are standing to the top of the obelisk are 65 degrees and 44 ...
September 10, 2014
Fannie eats a dozen doughnuts every 36 hours. How many doughnut does she eat in a week? I used Dimensional Analysis(which isn't helping at all), but it keeps giving me weird number, like 36 over 2016 or 252 over 2016.
September 1, 2014
What is the mass if solute dissolved in the indicated volume of each of the following solutions? (b) 4.25 L of 0.450 M KIO4g (c) 60.0 mL of 0.310 M ZnSO4g (d) 60.0 mL of 0.310 M Ni(NO3)2g
March 26, 2014
A hospital saline solution is analyzed to confirm its concentration. A 60.0 mL sample with a mass of 50.443 g is evaporated to dryness. (a) If the solid sodium chloride residue has a mass of 0.413 g, find the mass/mass percent concentration of the NaCl solution. % (b) Find the...
March 26, 2014
I need help please!! How many solutions does the system of equations have? 2x=-10y+6 and x+5y=3 a. one b. two c. infinitely many d. none y=4x+3 and y=4x+4 a. one b. two c. infinitely many d. none x-4y=12 and y=1/4x-3 a. one b. two c. infinitely many d. none
March 13, 2014
Ik this has been answered, but doesn't the copper oxide have something to do with it? And could you explain it in simpler terms? I'm just confused because you said forget the copper oxide, but your using it somehow, what puzzles me is the carbon dioxide, because the ...
February 23, 2014
A 475 gram box is given a push and it then slides up and back down a ramp with a 35.0° incline. The coefficient of friction is 0.30. (a) Determine the rate of deceleration as the box slides up the ramp. (b) Determine the rate of acceleration as the box slides back down ...
February 20, 2014
Calculate the final Celsius temperature of sulfur dioxide if 0.500 L of the gas at 35°C and 650 mmHg is heated until the pressure reaches 742 mmHg. Assume the volume remains 0.500 L.
February 13, 2014
Mike needs at least a 75% average to pass his math course. The class contains 5 exams that are equally weighted. If he scored a 64%, 86%, 71%, and a 90% on the first 4 exams, what score does he need on the final exam to earn at least a 75% in the class?
February 2, 2014
N2(g) + O2(g) → N2O5(g) What volume of oxygen gas reacts to yield 750.0 cm3 of N2O5? The reaction conditions are 350°C and 2.50 atm pressure. 2N2 + 5 O2 = 2N2O5 I balanced correctly. What is my next step to solve this problem. I am confused and I want to understand ...
February 2, 2014