# Posts by Scott

Total # Posts: 3,148

Trigonometry
Pythagoras ... x^2 + 35^2 = 37^2

Trigonometry
the diagonals bisect each other use the law of cosines to find the sides

science
the molar mass of HCl is ... 36.46 g

Mathematics
pyramid ... v = 1/3 (base area)(height) ... v = 1/3 * (2s)^2 * s = 4/3 s^3 prism ... v = l w h = 2s * 2s * s = 4 s^3

chemistry
the speed of sound in air is temperature dependent 337.5 m/s 10ºC

physics
the "beats" are the frequency differences a) 440 Hz ± (12/2) Hz b) 435 Hz ± (33/3) Hz which frequency is in both possibilities?

Math
6 min is correct ... but it is after 5:00 - not before

Math (Algebra)
if you subtract the equations (to eliminate y), you still end up with ... 0 = x^2 - x - 2 ... but you have used elimination even with elimination, you have to substitute back at some point to find all the variables

Math (Algebra)
x^2 = x + 2 x^2 - x - 2 = 0 (x - 2)(x + 1) = 0 x - 2 = 0 ... x = 2 x + 1 = 0 ... x = -1 the line intersects the parabola in two places plug the x-values into the equations to find the corresponding y-values

physics
time up equals time down ... Tu = Td half of the flight time (Tu) is spent climbing to the max ... h = 1/2 g (Tu)^2 the vertical velocity equals ... g Tu initial velocity is the vector sum of the vertical and horizontal ... V^2 = (Vh)^2 + (Vv)^2

Physics
Ff = ? m g cos(30º)

Honors Algebra
450 = 100 e^(kt) 4.5 = e^(6k) ln(4.5) = 6 k k = [ln(4.5)] / 6

physics
use the average speed on an interval, multiplied by the time of the interval add the three intervals

Physics
the two players experience equal but opposite impulses from the collision M1 * A1 = M2 * A2

MATH
half of the letters are vowels so, one half times one half

Math Check! #3
8C4 = 70

Math Check!
yes

physics
looks good

Physics
the force component of the box's weight along the ramp is ... m g sin(30º) the frictional force is ... ? m g cos(30º)

math
1st ... 1/4 * 7/16 2nd ... 1/4 * 7/15

Math
it's binary ... correct or incorrect P(correct) = 1/4 ... P(incorrect) = 3/4 (c + i)^50 .25^50 + 50 .25^49 .75^1 + 1225 .25^48 .75^2 ... + 1225 .25^2 .75^48 + 50 .25 .75^49 + .75^50 this is the expected outcomes for a simulation you could roll a 4-sided die (tetrahedron) ...

Statistic
I would agree

physics
30 km/s in a car!?!? that's about 3 times escape velocity

Math
10 - .13 < w < 10 + .13

Physics
a mole of gas occupies 22.4 L at 0ºC and 1 atm moles = (4.5/22.4)(273/350)(22/101) molecules = moles * Avogadro's number

Algebra
3 (b - c) = b + c 3b - 3c = b + c ... 2b = 4c

Geometry
the slant part of the cone (lateral area) is a sector of a circle the radius of the circle is the slant height of the cone ... Hs^2 = 62^2 + 12^2 the partial-circumference of the sector is the circumference of the base of the cone ... 24 ? LA = ? * Hs * 12 = 2381 base area...

math
the x-coordinate is constant, but the y-coordinate changes what does the slope equation (m = ?) tell you?

Math
the outside diameter is 8 ft more than the inside ? times 8 ft is about 25 ft 802 is WAY high

precal
it takes a second for the coin to reach max height, 16 ft above the balcony d = 1/2 a t^2 346 - 90 = 1/2 g t^2 solve for t, add in the 1st second

Math
50 cm * ? * 25

Physics
the deceleration is ... (13.0 -10.9) m/s / 2.20 s ... slightly less than 1 m/s^2 so it takes about 13 s to stop ... during which the average speed is ... (13.0 + 0) m/s / 2

Science
f = m a ... w = m g ... m = w / g

Physics
1/2 m v^2 = m g h h = v^2 / (2 g)

algebra
the question asks about "carriers" (like the RL parent) what percent is like the RL parent?

math
2 equations and 2 unknowns, just solve the system by substitution or elimination

math
looks good

algebra
the distance is the hypotenuse of the right triangle ... use Pythagoras

Algebra
the max A lies on the axis of symmetry Wmax = -b / 2a = -200 / (2 * -2) = 50

calculus
the quadratic solutions are relative max/min points on the graph (you obviously want the max) test the solutions in the original equation x < 4 because of the 8 in side

maths
the reflection is along a line through the center of the circle, perpendicular to the given line slope of perpendicular is ... -1 equation of perpendicular ... y-3 = -1 (x-2) ... y = -x + 5 intersection with reflecting line ... (1,4) center of reflected circle ... (0,5) center...

Math
subtract 8 ... -m/5 > 2 multiply 5 ... -m > 10 divide -1 ... m < -10

Gr 12 Data
a) 2^5 c) 2^3 ... arrangements of 3 middle coins d) 2^2 ... arrangements of 2 end coins e) yes , a coin toss is a coin toss

science
the masses are inversely proportional to the heights ... higher height means lower mass Hb Mb = Hj Mj

geometry
the general equation is ... (x - h)^2 + (y - k)^2 = r^2 r is the radius , (h,k) is the center

Statistics
25 people bought 35 cones so 10 people bought both 5 only van - 10 both - 10 only choc

geometry
(x - h)^2 + (y - k)^2 = r^2 the equation defines a circle of radius, r; centered at (h,k)

math
? rs = 20 b ... 1.1 ? rs = 22 b ? rs = 22 (b - .25) + .20 = 22 b - 5.3 .1 ? rs = 5.3 ? = 53

Maths
adding 5 ... | x | > 11 x < -11 , x > 11

Math
looks like #5

Math
how many are what age?

math
it's a 5-12-13 Pythagorean triple

Math
remember the hierarchy of operations ... PEMDAS adding 5 ... c/4 = 9 multiplying by 4 ... c = 36

word problem
Ar + Au + D + B = 267 Ar = Au - 8 D = 2 Au B = 5 Au + 5 substitute in the 1st equation to find Au ... then substitute back to find the others

Math
looks good

Physics 20
p1 exerts the same force on p2 that p2 exerts on p1 f = m a ... m1 a1 = m2 a2

Science
rethink #2

algebra
subtracting 5 shifts the 1st function 5 units down to give the 2nd function

binomial distribution
(s + f)^5 s^5 + 5 s^4 f + 10 s^3 f^2 + ... 10 s^2 f^3 + 5 s f^4 + f^5 s = p(success) = .687 f = p(failure) = 1 - p(success) = .313

Math
the terms are getting larger ... diverging

graphing help?
there is a website called fooplot you should use it

Bio chem
How many mL of 0.80 molar NaOH must be added to 20 ml of 0.40 of molar propionic acid, in order to produce a solution with a pH of 4.89? (PKa of propionic acid is 4.89.)

consumer math
2000 (1 + .08)^6

math
85000 + [(39637 - 35416) / .45]

Physics
boat components ... W ... 25 cos(35º) = 20 ... N ... 25 sin(35º) = 14 add the boat components to the current (14 N + 18 S) + 20 W = 20 ... the tan of the angle is ... S/W ... arctan(4/20) = 11º ... [W11ºS]

Math
the trip times are not the same, so the average speed is not 9 mph sorry, Ms. Sue

Math
d = r t ... t = d / r 27/60 = (d / 10) + (d / 8) 54/120 = (12 d / 120) + (15 d / 120) d is the distance to the lake

Math
get all the equations into slope-intercept form (y = mx + b) 1. the slopes are the same but the intercepts are different ... the lines are parallel ... they never intersect so no solution 2. the slopes are the same and so are the intercepts ... the lines lie on top of each ...

Math, Algebra
(2s + 5)(s - 6) = s^2 2s^2 - 7s - 30 = s^2 s^2 - 7s - 30 = 0 (s - 10)(s + 3) = 0

trig
Upper? plane ... N component ... 450 kph cos(45º) ... E component ... 450 kph sin(45º) wind ... N component ... 60 kph cos(30º) ... W component ... 60 kph sin(30º) add the components to find the resultant vector

math
it's four times as tall in the picture, so it's four times as tall in real life

Math
p + g = 20 4p + 2g = 70 solve the system using substitution or elimination

10 ft long and 4 ft wide is 40 ft^2

Algebra
4 w + 2 k = 62 w + k = 21 solve using substitution ... or elimination

physics
centripetal force is ... m v^2 / r a) (2 ? r) / 6.10 m/s b) m [g - (v^2 / r)] c) m [g + (v^2 / r)]

Physics (I have a test tomorrow)
the average speed of the car is 50 kph convert the speeds to m/s find the time to cover the 85 m find the change in kinetic energy ... KE = 1/2 m v^2 the work against resistance (friction) ... work = f d = 750 N * 85 m work and energy are the same thing add the work and the ...

Physics
the forces in c and d are normal (perpendicular) to the direction of motion of the car they do no work

physics problem
(2 * ? * 34 cm) / 39 m/s watch your units

Science
correct why the confusion?

Science
sounds like fermentation if there is oxygen, you get vinegar instead of wine

math
a- A = 12000 [1 + (.039/12)]^(6 * 12) b- subtract 12000 from a-

maths
no the ratio between the sides is not equal

math
A does 4/60 and B undoes 3/60 so 1/60 completed every 2 days after 112 days, 56/60 are done ... A completes the work on the 113th

algebra
6C3 ... 6! / (3! * 3!)

Math
it's a system of equations 5 V + 3 C + 2 M = 675 V = 2 C M = C + 75 substitute and solve

Math
x = 6 * 2^n

physics
cool the steam to 100ºC condense the steam cool the water to 0ºC freeze the water two specific heats heat of vaporization, and heat of fusion

Math
(300 / 500) * 250,000

Physics 1401
the center of mass of the stick is at the 50 cm mark ... 10 cm from the balance point the 6 g is 30 cm from the balance 10 * m = 30 * 6

Physic sucks 1401
the masses are linked by the string and have the same acceleration ... one upward and the other downward f = m a ... a = f / m (t - m1 g) / m1 = (m2 g - t) / m2 2t - 2g = 2g - t ... 3t = 4g ... t = 4/3 g the largest mass is 2 kg ... it gives about 20 N of force with the system...

Geometry Proofs
My teacher said she gave us everything.

Geometry Proofs
Trying to solve a proof. Triangle ABC. D is a point on side AC and E is a point on side BC. There is a line from Angle B to Point D and a line from Angle A to Point E. My Givens are AD = BE and BE>AE. I need to prove BC>AC. This is for my 7th grade geometry class. Thank ...

Chemistry
no some are not water soluble

math
look at 100,000 people 800 have it ... 56 will show negative ... 744 will show positive 99200 don't have it ... 2976 will show positive probability of accurate positive ... 744 / (744 + 2976)

math
(2 * 27.5) + 30/2

Math - combinatorics/ permutations
looks good

Chemistry
molarity is moles solute per liter of solution 0.05144 moles / .38 L = ? significant figures?

science
a + b = 29 a - b = 5 2a = 34 ... a = 17 ... b = 12 (17 + 3)^2 + (12 + 3)^2 = r^2

Physics
m g h + 1/2 m v^2 = 1/2 m V^2 (2 * 9.8 * 65) + 12^2 = V^2

Mathematics.
ER , 1/5 off , 4/5 normal , 80% normal ... normal = 64 / .80 MW , 15% off , 85% normal normal = 64.60 / .85

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