Tuesday

February 21, 2017
Total # Posts: 1,812

**PHYSIC 220**

(a)i = [19.6 * cos(153º - 90º)] - [16.7 * cos(136º - 90º)] j = [19.6 * sin(153º - 90º)] - [16.7 * sin(136º - 90º)] k = 2.40 - 0 (b) d = √(i^2 + j^2 + k^2)

*February 12, 2016*

**Geometry**

(100% + 25%) / 100% = 5/4

*February 11, 2016*

**Physics**

watts = volts * amps = amps^2 * Ω 600 W = 6 V * 100 A = 100^2 * Ω A)energy = 1/2 * farads * (volts)^2 B)use C and R (Ω) to find the time constant of the circuit the capacitor is 95% discharged after 3 time constants

*February 11, 2016*

**algebra**

Use the rational zeros theorem to find all the real zeros of the polynomial function. Use the zeros to factor f over the real numbers. f(x)= x^4+6x^3-11x^2-24x+28 Molon

*February 10, 2016*

**Chem**

it looks red because it reflects the red wavelengths and absorbs the others

*February 5, 2016*

**Physics**

uniform acceleration means that the average speed is the numerical average of the initial speed and the final speed average speed ... (30 + 60) / 2 = 45 60 s in a min ... 60 min in an hr distance = 45 * 60 * 60 * 2 (meters)

*February 5, 2016*

**chemistry**

divide the total moles by the total L moles ... (.125 * .43) + (.017 * 1.8) Liters ... .125 + .017

*February 5, 2016*

**math**

24 * 3/8 = ?

*February 3, 2016*

**Math**

9.15 / 6.10 = 1.5

*February 3, 2016*

**math**

1 1/2 is six quarters 6 * 3 = ?

*February 3, 2016*

**Chemistry**

525 mL of .5 M solution contains (.525 * .5) moles of solute since you get 2 Cl-ions from each CaCl₂ you will need...(.525 * .5 * .5) moles of CaCl₂, dissolved in 525 mL of solution molar mass of CaCl₂ is 111 g (.5 * .5 * .525 * 111) g of CaCl₂

*February 2, 2016*

**Math**

6t + 1x + 3f = 35 + 10 = 45...(A) t + x + f = 13...(B) t = x...t - x = 0...(C) (A) - 3 (B)...3t - 2x = 6 subtracting 2(C)...t = 6 substitute back to find x and f

*February 1, 2016*

**science**

let [NO₂] equal 2x (2x)^2 = 0.0466 * (1.0 - x) 4 x^2 + 0.0466 x - 0.0466 = 0 you can use the quadratic formula to find x but answer 5 is the only one that makes sense

*February 1, 2016*

**math**

graph y = x^2 and y = x^3 (use fooplot_dot_com) the intersections are the solutions

*February 1, 2016*

**physics**

clarifying Rp = 12.5 * g Rq = 9.5 * g

*February 1, 2016*

**physics**

p and q are 4.0 m apart moments around q 4 p = (10 * 5) + (4 * 2) - (8 * 1) p = 12.5 Rp = 12.5 g moments around p 4 q = (8 * 5) * (4 * 2) - (10 * 1) q = 9.5 Rq = 9.5 g

*February 1, 2016*

**math**

there is no solution they have the same experience step value; but the starting salaries are different a Q teacher with equivalent experience will always have a $2000 higher salary than an R teacher

*February 1, 2016*

**Math**

step 6 x = y = 1 so division by x-y is division by zero a BIG no-no

*February 1, 2016*

**math (grade6)**

if Connor sold p fewer than Cassie then Cassie sold p more than Connor Connor sold 50 so Cassie sold 50+p

*February 1, 2016*

**Physics**

at one time constant (τ) the current is approx. 63% of max

*January 31, 2016*

**science**

not much info...

*January 31, 2016*

**math**

x² = 26² - 24² this is actually a Pythagorean triple...5-12-13 in this case...10-24-26

*January 28, 2016*

**Math**

4 x ≤ 17.50 - 4.50 4 x ≤ 13 x ≤ 3.25

*January 28, 2016*

**Math- Algebra**

8 n ≤ 60 dividing by 8... n ≤ 7.5

*January 28, 2016*

**Math**

14 gal and 25 mpg means you can drive 350 mi on a full tank...14 * 25 36 mi per day for 10 days is 360 mi so you have to gas up on the 10th day you can drive for 9 days before refueling

*January 28, 2016*

**Math**

8 * (30 + 4) = 240 + 32 = 272

*January 28, 2016*

**math**

9 char for the 1st position 9 for the 2nd 8 for the 3rd 7 for the 4th 26 for the 5th 9 * 9 * 8 * 7 * 26

*January 28, 2016*

**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*