# Posts by scott

Total # Posts: 3,358

**science**

sound

**science**

a 3rd class lever

**Pre calc**

cot = 1 / tan = cos / sin sec = 1 / cos distributing ... (cot * tan) - (cot * sec) 1 - (1 / sin) = 1 - csc

**Physics**

sure, when you hit the brakes on a car, the acceleration is negative relative to the direction of travel

**Physics**

momentum is conserved and with an elastic collision, energy is conserved capital letters - larger ball small letters - smaller ball MV1 + mv1 = MV2 + mv2 ... (.3 * 2.5) + (.2 * 1.2) = .3 V2 + .2v2 1/2 MV1^2 + 1/2 mv1^2 = 1/2 MV2^2 + 1/2 mv2^2 ... (.15 * 6.25) + (.144) = .15 V2...

**basic chem**

2 * [(f - e) / P]

**simple algebra**

subtracting K ... H - K = log(A/C) 10^(H-K) = A/C ... C [10^(H-K)] = A

**Math**

?a = 4n + 12

**Math/Physics**

1/2 m V^2 = 1/2 m v^2 + m g h cancel the m's , solve for V ... or v in your equation algebra time

**Math**

yes

**math**

21000 + .0568

**AP Physics question**

gravity and the curved track are supplying the centripetal force if the required force is less than gravity (too slow in the loop), the coaster will not stay on the track

**math**

distance / time

**Math**

56000 * 80000 / 20000^2

**Math**

the line joining the midpoints is half the length of the triangle base the two triangles are similar, with the sides of the smaller triangle being half the size of the larger the areas are related by the square of the side relation

**Algebra 1**

d(x) = 22385 (1 - 0.14)^x

**math**

264 m/min * 60 min/hr = 15.8 km/hr 4.4 m/s * 3600 s/hr = 15.8 km/hr final conversion went awry

**Math**

by inspection , the sum is over 5 , and the denominator is 72

**Trig**

the bearing is 13º west of south 20 knots for 6 hr is 120 nautical miles south = 120 cos(13º) west = 120 sin(13º)

**math**

the measurements of the objects' weights are dependent on the actual (true) weights of the objects the true weights are independent variables I'm curious as to which "samples" the question refers to

**Physics**

it takes about ?2 sec for the acorn to reach the ground the direction the acorn is thrown, relative to the squirrel's position is a big factor ... the question is a little vague

**Algebra**

3. new vertex is (-3,2) ... y = (x - -3)^2 + 2 2. f(4) = |3(4) + 4| - 2 1. looks okay for vertical line test ... domain ... xmin to xmax ... range ... ymin to ymax

**Math**

alt+242 gives "?"

**Physics**

google "projectile range equation"

**Math**

1/2 = 6/12 1/3 = 4/12 1/4 = 3/12 the longest side is not longer than the sum of the two shorter sides , so a triangle can be made

**Math Combinatories**

166C9 * 103C5 * 34C2 * 4C1 * 1C1 does your calculator have an nCr function? google "nCr calculator"

**math**

the longest side cannot be longer than the sum of the two shorter sides

**Science Question PLEASE ANSWER QUICK! :D**

ozone filters the ultraviolet portion of sunlight UV is energetic enough to damage DNA

**Science**

mass / volume grams per cm^3

**Math**

half (50%) would be 120 a tenth of that (5%) would be 12 108 is 12 less than 120 ... 5% less than 50%

**Math**

you have a calculator, yes?

**Math**

check #7 ... it's less than 50%

**Science**

f = m a ... a = f / m

**Singapore math**

7 * (1200 - r) = 7200 - r

**math**

a gallon is 4 quarts

**Science**

an inclined plane reduces the force needed by increasing the distance (along the incline)

**Math**

L = heads of lettuce r = carrots u = cucumbers L + r + u = 890 ... r = 6L ... u = L + 10 substituting ... L + 6L + L + 10 = 890 solve for L , substitute back for r and u plug in the individual weights to find the total weight

**Mohan**

the insect's weight is distributed over several legs, so that the surface tension of the water is sufficient to support the insect

**Biology**

the man and woman are both hybrid brown with a blue recessive do a Punnett Square with Bb and Bb

**Math**

(5n + 3) * 4 = 72 solve for n

**math**

630 - 7n = 3n

**maths**

the work takes 120 man-days 10 men and 5 boys is like 12.5 men 120 / 12.5 = ?

**Chemistry**

p v = n R t ... n = (p v) / (R t) convert ºC to ºK make sure the R value has the correct units

**phyics**

the tennis ball and the machine have the same momentum, but in opposite directions ... Newton's 3rd law 68 * v = 0.057 * 38 TWO significant figures

**physics**

you want Newtons you have Newton?seconds, and seconds now what?

**mathematics**

if r is a root, then (x-r) is a factor (x-4)(x-7) = x^2 - 11x + 28 x^2 - 11x + 28 > 0 the parabola crosses the x-axis at 4 and 7 ... function values outside of the roots are greater than zero

**maths**

d is the difference between consecutive values in an AP ... there is only one value here ... 5 + d = 245 - d r is the ratio between consecutive values in a GP ... there would be two possible values ... 5 r = 245 / r

**Algebra**

set the equations equal to each other, and solve for x (looks like two points) plug the x values into either equation to find the y values of the intersection points

**maths**

the distance (d) is proportional to petrol 432 / 48 = d / 20

**Math**

100% is the whole thing 70% fewer means 30% of the whole thing if S is the number of subscribers (last year) ... then 774 is 30% of S .30 S = 774

**algebra math, 8th grade**

the hypotenuse is the LONGEST side

**As Physics**

an Ampere is a coulomb per sec 2 coulombs per sec ... 6.24E18 electrons per coulomb drift velocity is ... 1.0E-3 m/s so there are (2 * 6.24E18) free electrons in 1.0E-3 m of wire

**AP Chemistry**

5.495 is correct ... but it is (x 10^-9)

**Geometry**

looks good

**Math Probability**

look at 1000 new employees 700 took lessons ... 28 made mistakes in 1st month 300 did not take lessons ... 27 made mistakes in 1st month [1000 - (28 + 27)] did not make a mistake [700 - 28] took lessons

**Math - Cubes**

sorry Steve, it IS a pyramid...with either A or B as the vertex the base is an equilateral triangle consisting of three of the diagonals of faces of the cube the top of the cube is an identical pyramid the complexity is the section between the bases of the pyramids since the ...

**math**

since there are no "fractional" people, there are two ways to look at this the number is less than 108 the number is less than or equal to 107

**Chemistry**

the volume is proportional to the ABSOLUTE temperature (ºK) 200 cm^3 / (27 + 273) = v / (-3 + 273)

**Maths**

LENGTH = length * scale factor AREA = area * (scale factor)^2 VOLUME = volume * (scale factor)^3

**Science**

I think the path the question is referring to is the evolution of the star over its lifetime ... like the main sequence that is determined by the star's mass

**Algebra Help**

1. plug -4 and 12 into both equations to confirm the solution 2. graph the two equations...the solution is the intersection of the lines ... there are several graphing programs online ... or you could use graph paper, ruler, and pencil 3. solve the 2nd equation for x, in terms...

**algebra math, 8th grade**

what's the value of y on the x-axis? look for a point with that y value

**Math**

[(10/4 * 5) + (3/4 * 7/2)] / (10/4 + 3/4)

**math**

the square root of the area ratio

**math**

eliminate one of the variables by adjusting coefficients so you can cancel (eliminate) multiplying the 2nd equation by 3, gives the y-term a -3 coefficient ... 12x - 3y = 18 adding the 1st equation eliminates the y-terms find x , then substitute back to find y

**Science**

f = m a = 0.05 kg * 2000 m/s^2 = 100 N where did the 50 come from?

**algebra**

XY is all the letters raised to the 52nd power, multiplied together XY = [(-24389)^(1/156)]^52 = (-24389)^(1/3)

**physics**

v^2 / r ? 9.25g r ? v^2 / 9.25g

**Please Help asap: Math**

A and D are similar, but greater than or EQUAL to means a closed dot

**geometry**

figure??

**Math**

google, huh ... wow

**Math**

there is a calculator built into windows C...if you're still wondering

**Math**

3500 = x [1 + (.057 / 12)]^(12 * 5)

**math**

x is the number of gallons of 12% you should be worried...

**math**

(x * .12) + [(20 - x) * .07] = 20 * .10

**Algebraic inequalities**

x * .05 = 4[(1500 - x) * .025]

**Algebra 2**

good strategy [2^2 *(2^2)^x] / 2 = 2^10 (2^2)^(x + 1) = 2^11

**Maths**

draw two radii ... one to the end of the chord ... the other bisecting the chord the bisector is perpendicular to the chord this forms a right triangle use Pythagoras to find the distance

**Science**

the moments about the fulcrum are equal 100 * 2 = 0.5 * w m = w / g

**Physics**

Neptune's gravity provides the centripetal force the orbital altitude is not significant compared with Neptune's radius m v^2 / r = G M m / r^2 v^2 = G M / r ... = 6.67E-11 * 1.02E26 / (2.48E7)^2 result (v) is in m/s

**Algebra**

it's decay; because the base, being raised to a power, is less than one the percentage is the difference between the base and one .876 - 1 = -.124 = -12.4%

**Math**

the parentheses means that the 2 is distributed to both fractions (2 * 5/3) + (2 + 3/4) - 4/3 10/3 + 6/4 - 4/3 = 6/3 + 6/4 = 2 + 3/2

**Math**

so the tens digit is the ones digit cubed any number greater than 2 has a two digit cube 000, 111, 482

**Alegbra**

2nd test ... (15 * 75) + (25 b) = 40 * 80 1st test ... (15 * 80) + (25 * 70) = 40 m

**Alegbra**

need to know the number of boys and girls

**Math**

each of n teams plays n-1 teams twice ... but A playing B is the same game as B playing A n * (n-1) * 2 * 1/2 = 72 ... n^2 - n = 72 n^2 - n - 72 = 0 ... (n - 9)(n + 8) = 0

**Statistics**

a z-score table will give the number of s.d. above the mean for the 20% figure the z-score is .84 so 1200 mm is .84 s.d. above the mean 1200 - (.84 * 172) = ?

**geometry (check answer)**

slope of the 1st ... (0 - 4) / (2 - 0) = -2 slope of 2nd ... (2 - 3) / (-4 - -2) = 1/2 slopes are negative reciprocals lines are perpendicular

**Math**

there is something about the shape of the parentheses/brackets that excludes one end of an interval sorry...rusty on this part

**Pre-Cal**

g(x) = x - 7 ... when x = 7 , g(x) = 0 f/g is undefined the 1st choice is correct ... there should be notation that 7 is NOT included

**Pre-Cal**

all real numbers EXCEPT 7 ... division by zero is a NO-NO

**algerba math**

multiplying by 3 it's a 3 power series ... 3^2, 3^3, 3^4, ...

**math**

absolute = gauge + ambient ambient is usually atmospheric ... 14.7 psi

**Math**

subtracting the equations ... 0 = 5/2 x - 5 solve for x

**mechanicle engineering**

momentum is conserved 50000 * 30 = (50000 + 10000) * v ...1500000 = 60000 v ... v = 25 initial KE ... 1/2 * 50000 * 30^2 final KE ... 1/2 * 60000 * 25^2

**Math**

2011th term has had 2010 threes added to the 1st term, -4

**Chemistry**

in addition to being solid, ice floats the added buoyancy helps to support a person's weight

**Science - Climate change**

yes, water has a higher heat capacity (specific heat) than land also, solar energy (radiation) can penetrate deeper into the water the warmer air (over the land) is less dense and is displaced upward by the cooler air flowing in from over the water...sea breeze

**geometry**

it has to be long enough so that combined with the 4 m side, it can reach the end of the 9 m side to form the triangle it has to be short enough so that the 9 m and 4 m sides can close up the triangle (9 - 4) < s < (9 + 4)

**math**

that will work