# Posts by scott

Total # Posts: 2,489

**math**

if 2 in equals 75 ft, then 8 in equals 4 times 75 do the same conversion for 3 in area of the park is length times width

**precal 2**

2000 ft down the mountain is the 6º angle so his distance to the mountain is ... d = 2000 ft / tan(6º) the mountain above 2000 ft is ... h = d * tan(20º) = 2000 * tan(20º) / tan(6º)

**Math**

for two unknowns (m and n) you need two unique equations for a solution since there is only one complete equation ... the 2nd equation must be similar it seems that the 9 may be a typo ... probably a 6 instead 6m + 3n = 3 (2m + n) = 21

**math**

(80 - 67) / 8

**math**

12000 [1 + (.03 / 4)]^(7 * 4)

**Physics**

the c-o-m is between the c-o-m of the stick and the c-o-m of the stone the centers of mass for the stick and the stone are in their physical centers using some distance (d) from the center of the stick toward the center of the stone ... 2.5 * d = 10 * (40 - 18/2 - d) find d...

**Math**

the LCM for 15 and 20 is 60 every 60 minutes

**physics**

potential energy --> kinetic energy --> heat energy energy = m g h (in Joules) energy / specific heat = temp change A) and B) look like the same thing ... energy

**Algebra**

he drives 220 mi on 5 gal ... 44 mi/gal ... slope is the car's MPG miles on remaining fuel is the range of the car ... range is DEPENDENT on gallons of fuel gallons on x-axis ... range on y-axis no fuel means no range ... both intercepts are zero (the origin)

**algebra**

n/2 - 16

**Physics**

x-component ... 3.50 m * cos(145º) y-component ... 3.50 m * sin(145º)

**slope-intercept equation**

5y = 2x - 10 ... y = 2/5 x - 2 negative-reciprocal slope, same y-intercept y = -5/2 x - 2

**math**

72 / 60 = 1.2 = ? %

**math**

80 * 1.12 = ?

**Chemistry**

atomic mass ... 106.4 moles per ml ... 12.0 / 106 ...OOPS... 6.02E23 * (12.0 / 106) * 5.89E-23

**Chemistry**

atomic mass ... 106.4 moles per ml ... 106 / 12 6.02E23 * (12.0 / 106) * 5.89E-23

**math**

so ... replacement or not?

**math**

re Damon's answer after the 1st card is drawn, that suit has fewer cards than the other three suits ... the probability is not 1/4 it is 12/51 but his logic works

**math**

number of same suit pairs ... 4 * 13C2 number of pairs ... 52C2 probability ... 4 * 13C2 / 52C2

**science**

momentum is conserved 10 * 1.5 = (90 + 10) * v

**physics**

4.18 * (50.0/13.0) * [(90.0 - 87.0)/(90.0 - 30.0)]

**Math**

1 / (d + 1) = (d + 1) / (5d + 1) 5d + 1 = (d + 1)^2 ... d^2 - 3d = 0 ... d = 3 An = 3n - 2

**Chem**

each mole of zinc produces a mole of hydrogen gas a mole of gas occupies 22.4 L at STP

**physics**

it's half the distance, so it should be twice the weight

**College Physics**

1/2 k x^2 = 1/2 m v^2 ... k x^2 = 4.0 * 0.70^2 = 1.96 k x = 12 dividing equations ... x = 1.96 / 12 substitute back to find k

**Little star**

m g h = 1/2 m v^2 ... h = v^2 / (2 g) = 200 / g 1/2 g t^2 = 200 / g ... t = 20 / g t is half of the time of flight

**MATH**

4 cm x 4 cm x 7.5 cm

**math**

204 / (9/4)

**math**

this is binomial ... collect or not collect 15C11 * .6^11 * .4^4

**math**

A = B / 4 B - 6 - 12 = A + 12 ... B = A + 30 solve the system

**math**

D1 + D2 + D3 = 1274 D1 + 70 = D2 D2 + 84 = D3 solve the system

**physics**

avg vel is 5 m/s (Va) during .2 s passage, accel (A) is ... .2 * g find vel at top of window .. Vt = Va - (A / 2) find fall time (Tf) to top of window ... Vt / g drop distance is ... 1*2 * g * Tf^2

**physics**

v^2 / r = 5 g v = ?(5 * 9.8 * 450)

**Math**

4 w + 2 k = 78 w + k = 35 solve the system for coWs and chicKens

**math**

find two perpendicular lines from the three points by finding the slopes between the three pairs ... that is one corner ... you are looking for the opposite corner ... use the slopes from the ends of the sides to find the missing point this should be very simple by using graph...

**Science**

m * g * h ... answer is in Joules

**math**

21C3 / 26C3

**college physics**

free-fall time (t) ... 81.9 cm = 1/2 g t^2 horiz velocity = 36.5 cm / t vert velocity = g t the velocity is the resultant of the horiz and vert components

**college physics**

time in air (t) ... 56.3 m / 29.5 m/s height of bldng ... 1/2 g t^2

**Math**

(t / 3) + 3 = t / 2

**maths**

s = smaller , r = longer s + 17.5 = r r / 3 = 3 s / 4 ... 4 r = 9 s solve the system

**Math**

(y^2 + 8)^2 = 79 y^2 = -8 ± ?79 y = ± ?(-8 ± ?79)

**geometry**

the ground and the height of the helicopter form two sides of a right triangle a line from the copter to the accident forms the hypotenuse the angle between the vertical and the hypotenuse is ... (90º - 10.2º) for one accident ... and (90º - 8.7º) for the ...

**Maths**

w + d = 45 w - 5 = 6 (d - 5) solve the system for w and d the answer is (w - d)

**maths**

1.89 / 1.8

**science**

mass / volume

**Maths**

2 * 3,41 * 25 * 50

**physics**

one inch equals 2.54 cm a square yard is 36^2 square inches a square meter is 100^2 square cm $18.95 * 100^2 / (36 * 2.54)^2

**Geometry**

a rectangle is a parallelogram with supplementary opposite angles (and congruent adjacent angles) a square is a rectangle with equal sides

**physics**

average velocity is ... wo / 2 time to stop is ... rev / vel = 2 X / wo acc = vel / time = wo^2 / (2 X)

**Physics**

weight minus vertical pulling component ... Fn = 300 - 100 sin(35º) horizontal pulling component divided by normal force ... [100 cos(35º)] / Fn

**Pre-calculus**

two values ... going up and coming down 4 = 1 + 9 t - 5 t^2 ... 5 t^2 - 9 t + 3 = 0 use quadratic formula to find t

**Math**

2/8 * 16 = ?

**physics**

100^2 + 50^2 = v^2 ? is the angle East of North tan(?) = 50 / 100 = .5

**physical science**

mass * .227 * (15.0 - 10.0) = 543 answer is in grams

**Math**

10 u + t = 10 t + u + 45 9 u - 9 t = 45

**Number theory**

2^9 = 512 2^5 = 32 2^2 = 4 2^1 = 2 1000100110

**Maths**

the angles are supplementary (sum to 180º) 2x - 8 + 3x - 7 = 180

**Science**

K.E. = P.E. 1/2 m v^2 = 36 ... v^2 = 36

**Science**

a Newton per square meter is a Pascal 16 N / 16 cm^2 = 1 N / cm^2 = 10 kPa

**Physics, Calculus**

flying at 250 kph with a 50 kph cross wind 250 is the hypotenuse the third leg (speed along heading) is ... ?(250^2 - 50^2) the angle (?) between the ground bearing and the flight bearing ... sin(?) = 50 / 250 ... towards N

**Chemistry**

the initial acid molarity is ... [HA] = .112 * (22.32 / 25.00) = 0.100 [H+] = 10^(-2.87) = .00135 ... this is also [A-] Ka = [H+][A-] / [HA] = .00135^2 / (.100 - .00135) remember ... the initial molarity changes because of the dissociation

**Math**

if it were only 500 students; three pencils each is 1500 pencils looks like Amy calculated two pencils each

**math**

a line from the origin, through the center of the circle, intersects the circle at the nearest and farthest points the center of the circle is (6,2) find the equation of the line, then substitute into the circle equation to find the intersection points

**Math**

15000 = x [1 + (.03 / 2)]^(8 * 2)

**physic**

the 4200 should be Joules, NOT kJ

**Algebra**

multiply by [(x-2)(x+1)] ... common denominator [x(x+1)] + [(x-1)(x-2)] = (x-2)(x+1) multiply and collect like terms you'll be solving a quadratic equation

**Physics**

the average speed while stopping is ... (20 + 0) / 2 = 10 m/s t = d / r = 4 cm / 10 m/s = .004 s

**Physics**

f = m a ... 2000 = 800 * a ... a = 2.5 m/s^2 it takes 8 s to stop ... 20 m/s / 2.5 m/s^2 average velocity during stop ... (20 + 0) / 2 = 10 m/s ... sorry, pooch ...

**math**

100 MJ/s e = m c^2 ... 1E8 = m * (3E8)^2 m = 1.1E-9 kg multiply by seconds in a day

**physics physics**

f = m a ... twice both ... 10 = (5.0 + 2.0) * a tension ... t = 2.0 * a ... a from 1st calculation

**Math**

869374521

**math grade one**

two tens ten twos four fives five fours

**Geometry**

adjacent angles of a rhombus are supplementary ... they add to 180º opposite angles are congruent

**Physics 11**

moving time = fixed time * dilation factor 0.50 = t * 0.474974 not sure why you had division, not multiplication

**Physics 11**

remember the twins paradox? one stays on Earth, the other goes on a high speed (close to c) trip the one on Earth grows old, but when the traveler returns, he is still young time passes slower in the high speed reference frame so the beats will be wider spaced for Tamara

**math**

a = 1st term A.P. ... d = common difference 10 a + 45 d = 85 ... 2 a + 9 d = 17 (3a + 3d) / (4a + 6d) = (4a + 6d) / (8a + 28d) two equations and two unknowns

**pre-calculus**

8y = -(x^2 + 6x - 7) = -(x^2 + 6x + 9) + 16 y = -1/8 (x + 3)^2 + 2 ... vertex form -1/8 ... opens downward vertex is (-3,2) ... midway between focus and directrix focus is (-3,0) axis of sym ... x = -3 directrix is ... y = 4

**Physics**

coefficient of friction needed

**Calculus**

?/2 is 90º on the unit circle ... tan = y/x at 90º, x = 0 dividing by zero gives the infinite limit depending on the direction of approach to ?/2, the sign of the limit can be +/-

**mathhelop**

let x = number of hotdogs sold let s = sell price of hotdog let c = fixed operating costs p = profit p = x s - c substitute to find s and c 100 = 90 s - c -30 = 25 s - c adding equations ... 130 = 65 s ... 2 = s 100 = 90 * 2 - c ... 80 = c p = 2 x - 80

**Math**

ones ... >7 and 4n ... 8 tens ... 8 - 3 ... 5 hundreds ... 5 - 1 ... 4 thousands ... 5 + 4 ... 9

**Physics**

or high...

**Physics 11**

looks good

**Physics**

h = -1/2 g t^2 - 10.0 t + 5.00 find the time (T) when h equals zero (impact) v = 10.0 + g T

**Math**

let X equal the length along the river so 50-X is the distance away from the river A = 50 X - X^2

**math algebra**

looks like x times 11 equals y y = 11 x + 0

**maths**

if the sum of the 6 scores is greater than 480, then the average is greater than 80 (87 + 75 + 79 + 68 + 84 + x) > 6 * 80 393 + x > 480

**algebra**

it's fairly obvious ... troubleshoot it ...

**algebra**

B. calculation error C. zero is correct ... the rocket has to come back down at some point

**MATH**

so adults were 1/3 and young people were 2/3 (9 * 350) + [7 (700 - c)] + 5 c = 7650

**algebra**

the problem gives the speeds in both parts ... 62 mph in the 2nd part ... and 25 mph less in the 1st part let t be the time of reduced speed ... 37 t + 62(9 - t) = 450 find the time, then multiply by speed to find the distance

**Algebra 2**

f(x) = cos(x/4) + 1

**Math**

4 d 7 f 2 sides 4! * 7! * 2

**Physics 11**

f = m a ... 20 + x = 4 * 3 ... x = -8 friction = m g ? ... 8 = 4 * g * ?

**Math**

7x + 84 = - x^2 + 40 x - 6 x^2 - 33 x + 90 = 0 (x - 30)(x - 3) = 0

**algebra**

in 15 min the small hose fills 1/4 of the pool, while the big hose fills the other 3/4 3/4 in 15 min means 20 min to fill

**Physics**

corner to corner is one length and one breadth ... distance = 40 + 30 the diagonal is the hypotenuse of a 3-4-5 triangle ... displacement = ?(30^2 + 40^2)

**Lisa**

the 330 and 320 form a right triangle the hypotenuse is the horizontal displacement the horizontal and vertical displacements also form a right triangle since the three directions are orthogonal ... 330^2 + 320^2 + 10^2 = d^2

**Math**

4 m = 24 5 m = 40 N = 40 - 24