# R_scott

Newest questions and responses by R_scott-
## Science

google ... how-do-you-calculate-freezing-point-depression

*posted on March 22, 2019* -
## math/pre-calc

tmax lies on the axis of symmetry of the parabola ... -b / 2a ... -100 / (2 * -4.9)

*posted on March 22, 2019* -
## Science

a few need rework ... gravity seems to be a theme here Tides are caused by A) gravity. B) heat. C) waves.

*posted on March 22, 2019* -
## Physics

final energy = initial energy + energy from gravity 1/2 m Vf^2 = 1/2 m 16.0^2 + (m * 9.8 * 27.5) Vf^2 = 256 + (2 * 9.8 * 27.5)

*posted on March 21, 2019* -
## Math

yd^3 = 27 ft^3 3 ft^3 / (4 * 27 ft^3) = ?

*posted on March 20, 2019* -
## Precalculus

9/365 * 2 * π * 93 million

*posted on March 20, 2019* -
## math

1 foot by 1 1/2 foot

*posted on March 20, 2019* -
## Math

find the rate of fall ... (change in altitude) / (change in time) ... this is the slope of the line ... y = m x + b plug in one of the time/altitude points to find the y-intercept (b)

*posted on March 20, 2019* -
## Quadratics

you have three equations and three unknowns ... the unknowns are ... a, Vo, and So 144 = 1/2 a (.5^2) + Vo .5 + So 152 = 1/2 a (1^2) + Vo 1 + So 128 = 1/2 a (2.5^2) + Vo 2.5 + So solve the system for a, Vo, and So ... use the resulting equation to find max

*posted on March 20, 2019* -
## Math- Algebra

revenue = (500 - 20 x)(45000 + 5000 x) ... = 22500000 +1600000 x - 100000 x^2 xmax = -1600000 / (2 * -100000)

*posted on March 20, 2019* -
## Math

L + 2 W = 120 ... L = 120 - 2W area = L * W = (120 - 2W) * W = 120 W - 2 W^2 the maximum is on the axis of symmetry ... -b / 2a Wmax = -120 / (2 * -2) substitute back to find Lmax

*posted on March 20, 2019* -
## Physics

final speed = acceleration * time

*posted on March 20, 2019* -
## math

the radius is 10 cm (think about it) volume = π * radius^2 * height

*posted on March 20, 2019* -
## Algebra 2

from a z-score table the lower 20% is below ≈.842 σ

*posted on March 20, 2019* -
## Science (Physics)

reaction distance = speed * reaction time

*posted on March 20, 2019* -
## Math

v = 1/3 * area of base * height = 1/3 * π * r^2 * h the diameter is twice the radius

*posted on March 20, 2019* -
## Science

due to the Earth's axial tilt , constellations appear to move higher or lower in the sky, depending on the season

*posted on March 20, 2019* -
## Physics

heat = mass * specific heat * temperature change do the Al and Fe separately

*posted on March 20, 2019* -
## Science

average speed = 62.4 m / 4.20 s = (initial + final) / 2 change in speed = -5.60 m/s^2 * 4.20 s = initial - final solve the system for final

*posted on March 20, 2019* -
## maths

percent growth = [(change in height) / (starting height)] * 100%

*posted on March 20, 2019* -
## Math

a 4th order equation usually has 4 solutions b^4 + 2b^2 - 24 = 0 ... (b^2 + 6)(b^2 - 4) = 0 b^2 + 6 = 0 ... b = ± i √6 b^2 - 4 = 0 ... b = ± 2

*posted on March 20, 2019* -
## Chemistry

you're on the right track ... n is the total number of moles use the percentages to find the moles of each gas ... they have different heat contents

*posted on March 19, 2019* -
## math

2 * [(5 * 7) + (7 * 3) + (3 * 5)]

*posted on March 19, 2019* -
## Chemistry

the partial pressures are proportional to the mole fractions ... twice the moles, twice the partial pressure ... etc.

*posted on March 19, 2019* -
## Algebra 2

the maximum of the parabola lies on the axis of symmetry ... t = -b / 2a = -40 / -32 = 1.25 plug that into the height equation to find the max height

*posted on March 18, 2019* -
## math

umm ... you only got half of the surface area

*posted on March 18, 2019* -
## Trig

15% grade means that the tangent of the elevation angle is .15

*posted on March 18, 2019* -
## physics

work done by person ... 95.6 N * cos(35º) * .750 m work done by friction ... 75.5 N * .750 m the difference in the two work amounts is the kinetic energy of the box K.E. = 1/2 * mass * speed^2

*posted on March 18, 2019* -
## Physics

work = force * distance

*posted on March 18, 2019* -
## Newtonian Mechanics

1st part ... forces are m*g , distances are given 2nd part ... same forces ... distances are reduced by geometry ... distances equal to 1st part multiplied by sin(45º)

*posted on March 18, 2019* -
## Newtonian Mechanics

alternately use support 1 and support 2 as a fulcrum calculate the moments the mass of the beam acts in the center

*posted on March 18, 2019* -
## math

looks good

*posted on March 18, 2019* -
## Math

Volume = π r^2 h = 3.14 * 10^2 * 12 weight = V * 62.43

*posted on March 17, 2019* -
## Algebra

general circle equation ... (x - h)^2 + (y - k)^2 = r^2 circle centered at (h,k), with radius r

*posted on March 17, 2019* -
## Calculus

a trig substitution is used when calculating the integral as oobleck says, it's a standard trick

*posted on March 17, 2019* -
## math

yes

*posted on March 17, 2019* -
## math

the 2nd answer is correct ... use it to fix the 1st answer

*posted on March 17, 2019* -
## Math

s = smaller pump fill time ; b = bigger pump fill time s = b + 120 (144 / s) + (144 / b) = 1 [144 / (b + 120)] + (144 / b) = 1 144 b + 144 b + (144 * 120) = b (b + 120) 0 = b^2 - 168 b - 17280 convert answer to hours

*posted on March 17, 2019* -
## geometry

if the sum of the two smaller sides is ≤ the largest side ... a triangle cannot be made (won't close up)

*posted on March 16, 2019* -
## science

acceleration is changing speed, which falls under kinetic energy

*posted on March 16, 2019* -
## math

looks good

*posted on March 15, 2019* -
## math

the two lines mean "absolute value" ... just the number , no sign

*posted on March 15, 2019* -
## math

you plug the point into the equation and see if the equation is true x = 7 , y = 1

*posted on March 15, 2019* -
## Math

for each revolution of the tire , the bicycle travels ... 2.5 π ft revs = 5280 / (2 π)

*posted on March 15, 2019* -
## Algebra

it's arithmetic , so the missing term is the average of the ones on either side

*posted on March 14, 2019* -
## Algebra

9 ft * .8^3

*posted on March 14, 2019* -
## physics

by throwing the wrench away from the spaceship , she will give herself momentum towards the ship to me , this seems more like the 3rd law ... action/reaction

*posted on March 14, 2019* -
## math

0.275 x = 55 solve for x

*posted on March 14, 2019* -
## Math

parallel means the lines have the same slope ... their m's are equal y = 4 x + b ... through (1,6) plug in the point , and solve for b ... y = 6 , and x = 1

*posted on March 14, 2019* -
## science

try googling "rabbits in Australia"

*posted on March 14, 2019* -
## Physics

π/4 is the launch angle for maximum range on a level surface the vertical component of the launch velocity would be ... U √2 / 2 kinetic energy at launch is potential energy at peak ... U^2 / 4 = g h solve for h

*posted on March 14, 2019* -
## chemistry

1. moles = mass / atomic mass = 6.3 / 27 2. atoms = moles * Avogadro's number = moles * 6.02E23

*posted on March 13, 2019* -
## Math

what happened to the y that was already in the 1st equation?

*posted on March 13, 2019* -
## Science

acceleration = (change in speed) / (change in time) 2nd one looks good

*posted on March 12, 2019* -
## Algebra

x * .18 + (10 - x) * .40 = 10 * .20

*posted on March 12, 2019* -
## Math

1. yes ... it is the result of multiplying the equation by -1 2. no ... the left side can come from multiplication by -1 BUT ... changing a single sign in the right side polynomial is not a legitimate operation

*posted on March 12, 2019* -
## Science

_o_m_l_ VERY generous hint

*posted on March 11, 2019* -
## math

you are correct (90 - 75) / 75 = 20%

*posted on March 11, 2019* -
## Science

most meteors are chunks of comets that enter the Earth's atmosphere

*posted on March 11, 2019* -
## science

power = energy / time watt = joule / second

*posted on March 11, 2019* -
## science

speed = frequency * wavelength keep your units consistent ... m / km

*posted on March 11, 2019* -
## math

step 2 is incorrect subtracting 10 ... 2m^2 - 7m - 23 = 0

*posted on March 10, 2019* -
## chem

energy = specific heat * temperature change make sure all your units are compatible ... joules , grams , ºC , specific heat

*posted on March 10, 2019* -
## Stats

the z-score is the distance from the mean, measured in standard deviations points distance = z-score * σ

*posted on March 10, 2019* -
## Math

An becomes f(n) ... distributing the 6 ... 6n + 12 f(n) = 6 n + 12

*posted on March 9, 2019* -
## Math

n ≥ 2 looks like you're starting at 18, and adding 6 to each consecutive term An = 6 (n + 2)

*posted on March 9, 2019* -
## math

plug in the values 1, 2, 3, and 4 for n , and calculate the resulting terms

*posted on March 9, 2019* -
## Math

A = n B + k 15 = 2 n + k 45 = 8 n + k subtracting equations ... 30 = 6 n solve for n , then substitute back to find k

*posted on March 9, 2019* -
## Math

looks good

*posted on March 9, 2019* -
## mATH

draw a sketch and use the Pythagorean theorem BIG HINT ... it's a 3-4-5 triangle

*posted on March 8, 2019* -
## Math

how many fish did she catch? how many were trout? ... what fraction?

*posted on March 8, 2019* -
## Algebra

square the binomial and compare the results to find k (2x-3)^2 = 4x^2 - 12x + 9 (2x-3)^2 + k = 4x^2 - 12x + 13 check your calculations

*posted on March 8, 2019* -
## Science

read the "protist" article on wikipedia

*posted on March 7, 2019* -
## Algebra

there's only one rational number in the list ... you didn't pick it

*posted on March 7, 2019* -
## Physics

f = G * M1 * M2 / d^2 the masses are listed in Newtons, a force unit ... maybe a typo? the gravitational force equation uses mass ... is this happening on Earth? ... is g need for conversion?

*posted on March 6, 2019* -
## Physics

1st part ... d = 12 m/s * 30.0 s 2nd part ... ave speed = {12 m/s + [12 m/s + (1.5 m/s^2 * 8.00 s)]} / 2 ... d = ave speed * 8.00 s 3rd part ... top speed = 12 m/s + (1.5 m/s^2 * 8.00 s) ... d = top speed * 12.0 s add the displacements for the total

*posted on March 6, 2019* -
## math

start with easy and go to harder, if you have to assume a linear function ... y = m x + b when x is 0 , y is -1 ... so b is -1 when x is -2 , y is 9 ... 9 = -2 m - 1 ... 10 = -2 m ... m = -5 when x is 2 , y is -11 ... -11 = 2 m - 1 ... -10 = 2 m ... m = -5

*posted on March 6, 2019* -
## math

no input? arithmetic means add or subtract ... geometric is multiply or divide how do you get from one number to the next? what would be the next three numbers

*posted on March 6, 2019* -
## math

yes ... I do believe "clueless" substitute the values 1, 2, 3, and 4 for "n" in the given expression

*posted on March 6, 2019* -
## Science

from google ... abiotic ... "physical rather than biological; not derived from living organisms" if copper interferes with photosynthesis (a plant thing) , why B? maybe one person's rude , is another's tough love

*posted on March 6, 2019* -
## math

try plugging in one thru four for n

*posted on March 6, 2019* -
## Geometry

no givens...

*posted on March 6, 2019* -
## Math- please help

is there a relationship sign (like =, ≥, ≤, or something) missing?

*posted on March 6, 2019* -
## science

no diagram the 30º angle makes the most sense with the ceiling so the horizontal string force is ... m g sin(Θ) ... this is equal to the force of the electric field on the ball force = field strength * ball charge

*posted on March 6, 2019* -
## Science

where are they?

*posted on March 5, 2019* -
## math

no correction needed

*posted on March 5, 2019* -
## math

yes

*posted on March 5, 2019* -
## Math 6th grade

the + is between the number and two multiplication takes precedence (it happens first) over addition

*posted on March 5, 2019* -
## math

Damon ... look at the time stamps ... the answers are appearing almost simultaneously ... good group effort reality has to out shout stupidity

*posted on March 5, 2019* -
## math

the two spins are independent events P(vowel) = 1/3 P(K) = 1/6 multiply the probabilities

*posted on March 5, 2019* -
## math

P(red) = 8/43 P(blue) = 12/43 multiply the two probabilities (independent events)

*posted on March 5, 2019* -
## math

odds are different than probability ... favorable : unfavorable the probability of green is ... 6/11 the odds of green is ... 6:5

*posted on March 5, 2019* -
## Chemistry

looks good you might want to be aware of significant figures

*posted on March 5, 2019* -
## math

yes half of the numbers are even (divisible by 2)

*posted on March 5, 2019* -
## Algebra

there are eight cards in the hat , three of them with an I , five with another letter 3 I's , 5 not .. the odds of an I are 3:5

*posted on March 5, 2019* -
## Math

there are 6 ways to get doubles on the dice ... any of the six numbers on both dice ... 1-1, 2-2, 3-3, 4-4, 5-5, 6-6 there are 36 possible outcomes from rolling the dice ... any of the six numbers on one die, with any of the six numbers on the other die

*posted on March 5, 2019* -
## science

heat gained by water = heat lost by metal amount of heat = mass * specific heat * temperature change

*posted on March 5, 2019* -
## Math

it sounds like doubles on the dice...not any specific number her chances of winning are the same with both one number out of six on the wheel ... or 6 chances out of 36 with the dice

*posted on March 5, 2019* -
## Math

red (w/discount) ... $18 per gallon blue (w/discount) ... $20 per gallon (3 n * 18) + (2 n * 20) ≤ 500 54 n + 40 n ≤ 500 ... 94 n ≤ 500 ... n ≤ 5 15/47 3 n = 15 gal red ... 2 n = 10 gal blue

*posted on March 4, 2019*