Saturday

October 22, 2016
Total # Posts: 1,382

**General Chemistry**

the partial pressures are the same ratio as the product moles from the reaction equation p CO₂ = 2/9 * 2.50 atm p N₂ = 1/3 * 2.50 atm p H₂O = 4/9 * 2.50 atm

*January 28, 2016*

**Physics**

the horizontal component of the stone's velocity is ...12 m/s * cos(30º) multiply by 8 s to find the distance

*January 28, 2016*

**Physics**

the speed is the vector sum of the plane and the wind north and east are perpendicular, so it's a right triangle s² = 499² + 87²

*January 28, 2016*

**Science**

looks like D

*January 28, 2016*

**science**

the normal force is...5 g cos(30º) the force along the ramp is ... 5 g sin(30º) 5 g sin(30º) = μ 5 g cos(30º) sin(30º) / cos(30º) = tan(30º) = μ

*January 28, 2016*

**Science**

good answer

*January 28, 2016*

**Chemistry 101**

one inch equals 2.54 cm a mL is the same as a cm³ the volume of the ball (in mL) is 4/3 * π * 1.26³ looks like a floater

*January 28, 2016*

**Algebra**

1/f = 1/o + 1/i 1/(1/4) = 1/(1/2) + 1/i 4 = 2 + 1/i i = 2

*January 28, 2016*

**Chemistry 101**

s.h. = 3450 / [10.65 * (99.9 - 28.5)]

*January 28, 2016*

**Chemistry 101**

mass = 1.2347 lb * 453.6 g/lb width = 1.256 ft * 30.48 cm/ft D = mass / [width * 12.6 * 45.6] the answer should be rounded to 3 significant figures

*January 28, 2016*

**Wave**

greater

*January 27, 2016*

**science**

the Sun appears to move across the sky because the Earth is rotating the Sun "moves" westward, so the Earth is rotating eastward

*January 27, 2016*

**Math**

bike...d = 6t ... d/6 = t bus... 26 - d = 30 (t - 1/3) substituting...26 - d = 30 (d/6 - 1/3) 26 - d = 5d - 10 36 = 6d

*January 26, 2016*

**Physics**

flying N at 250 km/h for 30 min should put him at 125 km N of the start the wind has pushed him 75 km N and 40 km W in 30 min so the wind is blowing 150 km/h N and 80 km/h W Vw² = 150² + 80² the tangent of the angle (west of north) is...8/15

*January 26, 2016*

**Physics**

the velocities add as vectors they are perpendicular to each other v² = 6² + 4²

*January 26, 2016*

**Science**

protons are positively charged so it would repel electrons are negatively charged so it would attract

*January 26, 2016*

**Physics**

the radius of the Earth is 6.37E3 km gravitational force is inversely proportional to the square of the distance 9.81 * (6.37E3)² = 6.44 * (6.37E3 + h)²

*January 26, 2016*

**Coulomb's Law**

the force is inversely proportional to the square of the distance (inverse-square relation) the new force is 4 times the original 1 / (1/2)² = 1 / (1/4) = 4

*January 26, 2016*

**math**

the change is $5 that is 25% (5/20) of the starting value

*January 26, 2016*

**Math**

losing time means running too slow when an hour has passed, the clock has only moved 45 min it is running at 3/4 speed (45/60) so when it shows an hour has passed, an hour and 20 min (4/3 hr) has actually passed the correct time is...10:20 AM

*January 26, 2016*

**Physics**

pressure is measured in Newtons per square meter or Pascals 20 m below the surface, there are 20 cubic meters of water stacked up 20,000 kg * 9.8 m/s² = 2.0 x 10⁵ N the water pressure is...2.0x10⁵ Pa the total pressure is...3.0x10⁵ Pa

*January 26, 2016*

**Physics**

t equals the fall time 0 = -4.9 t² + 1000 horizontal distance to target d = t * 200 km/hr convert km/hr to m/s the tangent of the angle is the height of the plane, divided by the horizontal distance to target

*January 26, 2016*

**science**

the kinetic energy of an object is equal to one half of the product of the object's mass and the square of its velocity KE = 1/2 m v²

*January 26, 2016*

**physics**

charge = capacitance * voltage coulombs = Farads * volts

*January 26, 2016*

**Chemistry**

each molecule of ammonium nitrate yields one ammonium ion and one nitrate ion so, twice the number of moles that you started with

*January 26, 2016*

**Mathematics**

draw the picture... d = h / tan(52º)

*January 26, 2016*

**Science**

a galvanometer measures current an electromagnet is the active element try B.

*January 26, 2016*

**physics**

see physics/tom about ten questions below this

*January 26, 2016*

**physics**

(a) v = 100 m / 8.70 s (b) constant acceleration (from zero) means that the average velocity during the acceleration phase is half of the final velocity (v/2) t + v (9.58 - t) = 100 m plug in v and solve for t (c) average acceleration is v/t

*January 26, 2016*

**Science**

the force (in Newtons) equals the product (multiply) of the charges (in Coulombs) divided by the distance (in meters) squared f = q₁ q2 / d²

*January 26, 2016*

**math**

this is true because a diameter is a straight line connecting two points on the circumference of a circle

*January 25, 2016*

**Chemistry**

the balanced equation reveals the answer C₃H₈ + 5 O₂ ---> 3 CO₂ + 4 H₂O looks like 6

*January 25, 2016*

**phy 231**

3.05 = -1/2 g t^2 + v sin(α) t + 2.10 19.2 = v cos(α) t plug in sin and cos values solve the system for v (and t)

*January 24, 2016*

**Maths**

5a + 10d + 7a + 21d = 167 10a + 45d = 235 solve the system for a and d S₂₀ = 20a + 190d

*January 24, 2016*

**Physics**

h = -1/2 g t^2 + 100 t + Ht 0 = (-4.9 * 25^2) + 2500 + Ht

*January 24, 2016*

**science**

to double the volume at a constant pressure, you have to double the ABSOLUTE (Kelvin) temperature 0ºC = 273.15ºK

*January 24, 2016*

**statics**

a score of 105 is one standard deviation above the mean the rule says that 68% of a normally distributed population lies within one standard deviation of the mean...half above the mean and half below so 34% are within one standard deviation above the mean this means that 16% ...

*January 24, 2016*

**ALgebra**

t for ten and w for twenty t + w = 54 10 t + 20 w = 780 solve the system

*January 21, 2016*

**Science**

you don't have any units ... and Mars is more than a light-second away

*January 21, 2016*

**Physics**

let's call right positive momentum is conserved (5 * 4) - (2 * 6) = (5 * .8) + (2 * v) 8 = 4 + 2v

*January 21, 2016*

**physics101**

how far from the end of the platform?

*January 21, 2016*

**Chemisty**

yes, it's A because the specific heat is lower, it takes less heat to raise the temperature a greater temperature change for a given amount of heat means that the temperature changes faster

*January 21, 2016*

**physics**

the desired acceleration is twice the gravitational acceleration, in an upward direction so the required force is 3 g's f = m a = 5 * 30 = 150 N

*January 20, 2016*

**Chemistry**

Cl is -1, so the Fe is +2 or +3

*January 19, 2016*

**Physics**

gravitational force parallel to the plane is...m * g * sin(30º) If the efficiency of the plane is 75%, then the coefficient of friction is .25 the normal force is...m * g * cos(30º) so the minimum force is [m * g * sin(30º)] + [m * g * cos(30º) * .25]

*January 19, 2016*

**math**

let t equal the fill time the pipes each fill a fraction of the pool the fractions sum to one (the whole pool) one fraction is t/8 the other is t/12 t/8 + t/12 = 1 24 is the LCD 3t + 2t = 24

*January 19, 2016*

**Chemistry**

it takes 4.179 J of heat to change the temperature of 1 g of water by one ºC 209 / (10.0 * 4.179) = temp. change looks like about a 5ºC increase

*January 19, 2016*

**Chemistry**

1 L of .1 M contains .1 moles volume = .1 mole / 12.1 mol/L .1 / .0121 mol/ml = ?

*January 19, 2016*

**Chemistry 101**

there are 2.54 cm in an inch a cm^3 is the same as a mL volume = π * .5^2 * 2.5 * 2.54^3 ...the result is in cm^3 multiply the volume by the density (.26)...that is the mass in g round the result to TWO sig fig ...that is the limiting number in the density value

*January 19, 2016*

**Chemistry 101**

there are 2.54 cm in an inch volume = π * 3.25^2 * 12 * 2.54 * 100 ...the result is in cm^3 ...it also equals the mass in g there are (approx) 453.6 g in a pound ...divide to find the mass in pounds

*January 19, 2016*

**Chemistry 101**

there are 2.54 cm in a inch ...12 inches in a foot ...5280 feet in a mile multiply to find the cm in a mile ...divide by 100 to find the meters convert 9.37 x 10^7 mi to meters ...by multiplying divide the result by 3 x 10^8 the answer is in sec ...THREE significant figures...

*January 19, 2016*

**Math**

there are 10 marbles, with 3 pink so the probability of pink is 3/10 for 2 pink draws (with replacement) ...probability = .3 * .3

*January 19, 2016*

**math**

3 differences (7 to 10) is 9 so d = 9 / 3 = 3 the 7th term is 6 differences from the 1st term ...1st + (3 * 6) = 7th ...1st + 18 = 19 so the 1st three terms are ...1, 4, 7

*January 19, 2016*

**physics**

momentum is conserved Mb * V1b = (Mb * V2b) + (Mp * Vp)

*January 18, 2016*

**Physics**

does your instructor teach significant figures?

*January 18, 2016*

**physics**

google electromagnetic spectrum energy

*January 18, 2016*

**trigonometry**

by Pythagoras 10^2 + x^2 = (20 + x)^2 x^2 + 100 = x^2 + 40x + 400 -300 = 40 x there appears to be something wrong with the numbers in the problem

*January 18, 2016*

**math help please**

did you check your 1st posting?

*January 18, 2016*

**math help please**

check your mail

*January 18, 2016*

**Math ASAP**

6. C 7. A distribute first then combine like terms

*January 18, 2016*

**Physics**

the tangent of the elevation angle is the bullet drop (1.13 m) divided by the target distance (120 m)

*January 18, 2016*

**Math ASAP**

4. 2x = -2 7. correct

*January 18, 2016*

**help on math**

30% farther is 260 ft (200 * 1.30) up 25.5 and down 40.5 is a net down of 15 260 + 15 = ?

*January 18, 2016*

**Math**

double the first EQUATION , then subtract THE 2ND EQUATION to get y 2x + 4y - 2x - 3y = 22 - 50 y = -28 substitute into the 1st equation to find x

*January 18, 2016*

**Algebra**

90 + .7 m < 60 + .8 m 30 < .1 m 300 < m

*January 18, 2016*

**High school mathmetics**

using 10 sales (he may have more or less) [(500 * 4) + (600 * 6)] / 10 = 560

*January 18, 2016*

**Pre Calc**

the radius is √[3^2 + (-1)^2] = √10 sec(Θ) = √10 / 3

*January 18, 2016*

**Math**

one orbit in 3 hr 360º in 3 hr = 120º / hr 2º / min

*January 18, 2016*

**Physics**

an Ampere is a coulomb per second you're off by a factor of 60

*January 18, 2016*

**math help**

every 4 months is 3 times a year for 2 cars, 6 oil changes 6 * 4.5 = 27 qt of oil (27 / 5) * 14.99 = ? looks more like B but if the oil has to be purchased in 5 qt increments then 27/5 means 6 containers (answer C) but (again) there is oil left over that can be used next year ...

*January 18, 2016*

**8th grade math and algebra class**

y is usually graphed as a function of x bags on the x-axis total cost on the y-axis you should get a line with the slope changing at intervals you may need different scales on the two axes

*January 18, 2016*

**Physics**

m g = 2 * 1/2 k x^2 m g = k x^2 m g / x^2 = k

*January 17, 2016*

**Physics**

Vbullet = Vblock-bullet * (Mblock-bullet) / Mbullet 1/2 Mbb Vbb^2 = Mbb g * .658 * 6.66 Vbb = √(2 g * .658 * 6.66)

*January 17, 2016*

**Math/ algebra**

you found the answer...1/16 6.25%

*January 17, 2016*

**Maths**

just find the perfect squares on either side of the given root A) √4 , √9 --- 2, 3 B) √25 , √36 --- 5, 6 the rest work the same way

*January 17, 2016*

**chem**

Zn + 2 HCl ---> ZnCl₂ + H₂ so .1 moles of HCl reacts with .05 moles of Zn molar mass of Zn is 65.38 g .05 * 65.38 = ?

*January 17, 2016*

**Chemistry**

the temperature change of the air is 10.0ºk (C)...not 283.15

*January 13, 2016*

**Physics**

the change in energy from the bottom of the circle to the top is... (m g h) h = 90 cm the centripetal force at the top is only gravitational... m g velocity at top ... m v^2 / r = m g ___ v = √(r g) ... r is 45 cm the KE at the bottom equals the KE ___ at the top, PLUS (...

*January 13, 2016*

**Math**

adding 7 __ 4e^(-.03x)=20 dividing by 4 __ e^(-.03x)=5 taking natural log __ -.03 x = ln(5) dividing by -.03 __ x = ln(5) / -.03

*January 13, 2016*

**Algebra**

the 1st two answers are EQUATIONS of lines parallel lines have the same slope so just change the +7 to something else you are right about the perpendicular slope__so change the -2 to 1/2 the x-intercept means that y equals zero__so plug in zero for y and find x the form will ...

*January 13, 2016*

**Math/Physics**

1st measure __ h / tan(19º) = d 2nd measure __ h / tan(28.3º) = d - 910 substitute for d and solve for h

*January 13, 2016*

**Math**

If I put $20,000 into a CD in 1990, with a recurring 8.125% interest rate, how much would that amount to in 2015?

*January 11, 2016*

**english**

Which sentence is correct? a.Each guitar must be in their own case. b.Each guitar must be in its own case.****** c.Each guitar must be in his or her own case. ******-answer

*December 11, 2015*

**english**

is it C. why wouldn't it be B

*December 9, 2015*

**english**

Which sentence is punctuated correctly? a.“Thunder is good,” said Mark Twain, “But it is lightning that does the work.” b.“Thunder is good, said Mark Twain, but it is lightning that does the work.” c.“Thunder is good,” said Mark Twain...

*December 9, 2015*

**Chemistry**

nope mr estrada, i didnt, thats why i asked you

*December 9, 2015*

**Chemistry**

Did u think about it?

*December 9, 2015*

**Math **

Arianna is taking care of her uncle's dog during the week. He left 3 cans of food for 5 days. How much good should she give each day assuming the dog eats exactly the same amount each day

*December 6, 2015*

**algebra**

two mechanics worked on a car the first mechanic worked for 15 hours and the second mechanic worked for 5 hours together they charged a total of 1525 what was the rate charged per hour by each mechanic if the sum of the two rates was 175 per hour

*November 3, 2015*

**Math**

If you would walk around the earths Equator with an average speed of 5 miles per hour, how many days would you need to walk to come back to your starting point?

*October 21, 2015*

**math**

how to explain to my son write doubles fact you can use to find the sum.Write the sum 2+3=

*October 19, 2015*

**Math**

Mara finished 1/5 of her assignment on Saturday and 3/8 of her assignment on Sunday. What fraction of her assignment did she complete on Saturday and Sunday? --Thank you!--

*September 30, 2015*

**Algebra**

The boat travels 60 miles to an island and the same 60 miles coming back. Changes in the wind and tide made the average speed on the return trip 3 mph slower than the speed on the way out. If the total time of the trip took 9 hours, find the speed going to the island and the ...

*August 1, 2015*

**math**

express a single logarithm 1/3 log(b, x+3) log(b, y-4) log(b, x)

*June 23, 2015*

**math**

$8669.93

*June 23, 2015*

**physics**

A body is projected at an angle of 30degree to the horizontal with a velocity of 150metre per seconds.Calculate the time it takes to reach the greatest height,take g=10metre per seconds square and neglect air resistance.

*June 18, 2015*

**math**

A can of oil is 8 inches high and 8 inches in diameter. What is the approximate volume of the can?

*June 6, 2015*

**Physics**

A person whose mass is m = 96.0 kg steps on a mechanical bathroom scale placed on an inclined plane that makes the angle α = 15.3° with the horizontal. What is the reading on the scale?

*May 28, 2015*

**Statistics**

The manager of a company wants to investigate job satisfaction among its employees. One morning after a meeting, she talks to all 25 employees who attended. Does this sampling plan result in a random sample? What type of sample is it? Explain.

*May 13, 2015*