Tuesday

February 28, 2017
Total # Posts: 1,868

**physics**

s.h. = 4186 4186 * 2 * 75 = 627900 rounding or sig fig?

*October 19, 2016*

**algebra**

3^3 * (a^2)^3 = 27 a^6

*October 19, 2016*

**physics**

momentum is conserved the speed is zero

*October 19, 2016*

**physics**

the mass is not a factor horizontal speed = Sh = S cos(54.5) the flight time to the basket is ... 10.4 m / Sh = 10.4 * cos(54.5) / S vertical speed = Sv = S sin(54.5) gravity slows the vertical speed to zero at the peak, halfway through the flight Sv / g = 1/2 * 10.4 / Sh S...

*October 19, 2016*

**math**

(1.05^7 - 1) * 100%

*October 19, 2016*

**math**

a. 4000 = A [1+(.104 / 365)^(11 * 365) b. 4000 = A e^(.104 * 11)

*October 19, 2016*

**physics**

a) after 1 s the vertical velocity is 2 m/s ... so the average velocity is 7 m/s for the 1st sec b) similar to a) ... the object reaches its peak after 1.2 s ... the average velocity is 6 m/s c) time up equals time down ... 1.2 + 1.2

*October 19, 2016*

**physics**

time up equals time down h = 1/2 g t^2 = 4.9 m/s^2 * (2 s)^2

*October 19, 2016*

**physics**

60 = 1/2 k x^2 x = √(120 / 460)

*October 18, 2016*

**physics**

1/2 k x^2 = 1/2 m v^2 k = m v^2 / 4.5^2 convert 60 km/hr to m/s and calculate

*October 18, 2016*

**Arithmetic progression**

10 is not correct ... the 10th term is 23 the difference between terms is 2 27 is (5 + 22) ... the 1st term plus 11 differences ... 27 is the 12th term

*October 18, 2016*

**math**

57 (60 - 3) are M, E, or ME ... E + M + ME = 57 ... E + M = 48 M + ME = 2 (E + ME) ... M + 9 = 2E + 18 ... M = 2E + 9 substituting ... E + 2E + 9 = 48 ... E = 13 (i) M + ME (ii) E + ME (iii) M (iv) E

*October 18, 2016*

**Physics**

he has a constant velocity (zero acceleration) so the net force on him is zero the frictional force must equal his weight

*October 18, 2016*

**algebra**

(4y + 1i)(4y - 1i)

*October 18, 2016*

**Physics**

if his last turn is to the south he will be 70 m S and 12 m W of his starting position use Pythagoras to find the displacement

*October 18, 2016*

**GENERAL PHYSICS**

100 * 2π / 60 / 2 sec

*October 18, 2016*

**math**

36 / 47 = x / 120

*October 18, 2016*

**Chemistry**

mole = 6.02E23 particles 5.43E24 / 6.02E23

*October 18, 2016*

**math help**

1/2 * b * h = 10 b = h + 1 substituting ... h^2 + h - 20 = 0 (h + 5)(h - 4) = 0 h - 4 = 0

*October 18, 2016*

**Physics**

A) 2 * 7 * 10 N to the left B) 2 * 1/2 * 10 * 7^2 J C) the PE from B is converted to KE ... v = √[2 * B / m]

*October 18, 2016*

**math**

a = 2 pt, b = 4 pt, c = 5 pt a + b + c = 28 2a + 4b + 5c = 100 a = 2c 2a + 2b + 2c = 56 ... substituting ... 3a + 2b = 56 4a + 8b + 10c = 200 ... substituting ... 9a + 8b = 200 subtract the equations (after multiplying) to eliminate b

*October 18, 2016*

**Physics**

a faster stop (because concrete is hard) means a greater impulse

*October 18, 2016*

**physics**

the ball's speed is being converted to gravitational potential energy 1/2 m 6.4^2 = ... m g (2.2 - 1.5) + 1/2 m v^2 6.4^2 = 1.4 g + v^2

*October 17, 2016*

**Math**

s + b + w = 42 s = 4b 3s + 2b + 1.5w = 102 substituting ... 5b + w = 42 ... 14b + 1.5w = 102

*October 16, 2016*

**Math**

2 ft^3 = 2 * 12 * 12 * 12 in^3 24 * 144 / 231

*October 16, 2016*

**phy 101**

momentum is conserved so they "trade" velocities

*October 16, 2016*

**Math**

64, 32, 16, 8, 4, 2, 1, 1/2

*October 16, 2016*

**Physics**

a. weight = mass * g b. normal force equals weight ... but in opposite direction c. Newton's 2nd law ... f = m a ... in this case ... a = f / m d. correct

*October 16, 2016*

**Chemistry**

molar mass of acetone ... 58.08 g moles of acetone ... 1.920 / 58.08 molar enthalpy is energy per mole

*October 15, 2016*

**Physical science**

(A) m g h = 15 m g (B) m g h = 1/2 m v^2 ... v = √(2 g h) = √(30 g)

*October 15, 2016*

**Math**

it takes 12 min (the LCM of the numbers) divide by their rates to find the number of laps

*October 15, 2016*

**Math 1105**

yes

*October 14, 2016*

**Physics**

there is no force in the horizontal direction (gravity is vertical), so the horizontal velocity remains constant

*October 14, 2016*

**math**

the longest side must be less than the sum of the two shorter side the difference between the longest and shortest sides must be less than the middle side L + A = 11 L < (A + 4) ... L < (11 - L + 4) ... 2 L < 15 ... L < 7.5 L = 7, A = 4

*October 14, 2016*

**Physics**

A) 18 m/s * 6 s B) 1/2 g t^2

*October 14, 2016*

**Math**

1:12::8:x

*October 13, 2016*

**chem**

(a) 0.5 * (20.00 / 25.0) * (250.0 / 25.0) (b) multiply the answer from (a) by the molar mass of HCl

*October 13, 2016*

**algebra**

a + b = 273 / 3 mph = 91 mph a - b = 7 mph adding equations (eliminating b) ... 2 a = 98 mph

*October 12, 2016*

**Physics**

the horizontal velocity is ... 31 m/s * cos(60º) the vertical velocity is ... 31 m/s * sin(60º) + ... 3.4 s * -9.8 m/s^2 add the two component vectors ... a^2 + b^2 = c^2

*October 12, 2016*

**problem solving**

s = m - 8 m - 6 = 3(s - 6) = 3 s - 18 m - 8 = 3 s - 20 susbstituting ... s = 3 s - 20 ... 20 = 2 s

*October 12, 2016*

**Physics**

height = 1/2 g t^2 + Vo t + Ho 0 = -4.90 * .750^2 + Vo * .750 + 4.80

*October 12, 2016*

**Physics**

the difference in total energy (kinetic plus potential) at the base and the top; is the energy input from the engine the ascent time is the average speed, (top + bottom) / 2; divided by the 4.40 km distance energy / time equals power your answer has 5 sig figs. but all the ...

*October 12, 2016*

**Physics**

energy = m g h = 73.0 * 9.81 * 420 time = 60 * 15 + 10 power = energy / time

*October 12, 2016*

**physics**

his weight plus the centripetal force must equal 1170 N 83.0 [g + (v^2 / r)] = 1170 v^2 / 18.0 = (1170 / 83.0) - 9.81

*October 10, 2016*

**physics**

pulling at an angle reduces the frictional force (by reducing the normal force) so the frictional force is ... .42 * {(85 * g) - [F sin(38º)]} the block is in equilibrium when the frictional force equals the horizontal component of the pulling force ... F cos(38º) ...

*October 10, 2016*

**Math**

(n / 3) - 7 = 0 n / 3 = 7 n = 7 * 3

*October 10, 2016*

**College Algebra**

y = a b^x 8 = a b^0 ... a = 8 2.4 = 8 b^1 ... .3 = b y = 8 * .3^x

*October 10, 2016*

**MATH**

division by zero is a no-no ... even 0/0 so the 2nd and 4th are undefined

*October 10, 2016*

**Algebra**

Q = 5 * 2^(S + 4)

*October 10, 2016*

**College Algebra**

5 * 1.083^13

*October 10, 2016*

**physics again**

the water velocity increase is due to the change in gravitational potential energy 1/2 m 3.00^2 - 1/2 m 2.07^2 = m g h 3.00^2 - 2.07^2 = 2 g h the kinetic energy of the jump is converted to gravitational potential energy 6.26^2 = 2 g h the max waterfall is the sum of the two ...

*October 9, 2016*

**physics**

the average speed over the interval is (3.00 m/s + 5.60 m/s) / 2 = 4.30 m/s 2/3 of its length is 1.00 m so the time of the interval is ... 1.00 m / 4.30 m/s the change in speed is ... 5.30 m/s - 3.00 m/s acceleration is ... speed change / time

*October 9, 2016*

**Physics**

dx = (14 t - 32) dt x = 7 t^2 - 32 t + c 25 = 7 (3^2) - 32 (3) + c 25 = 63 - 96 + c ... 58 = c x = 7 t^2 - 32 t + 58

*October 9, 2016*

**physics**

gravity is the centripetal force keeping the satellite in orbit g = m a = 76 kg * .63 m/s^2

*October 9, 2016*

**physics (super hard)**

the centripetal force at the top of the circle equals gravity v^2 / r = g v = √(g r)

*October 9, 2016*

**math**

a. v = 1/3 * pi * r^2 * h b. the base radius is 4 and the height is 3, so the slant height is 5 (3-4-5 triangle) the 5 is the radius of the circle of which the area of the cone is a segment ... the area of the circle is...25 pi the area of the cone is...4/5 * 25 pi

*October 9, 2016*

**math**

7 is the most likely outcome using distinguishable dice, there are 36 possible outcomes ... each of the six faces on a die can pair with the six faces on the other die ... 6 * 6 = 36 twelve of those outcomes result in a sum of 7 ... one third of the rolls

*October 9, 2016*

**Physics**

k = f / e k1 e1 = k2 e2 e2 / e1 = k1 / k2

*October 9, 2016*

**chemistry**

call the 2nd gas B 3 g of B is half as many moles as 2 g of A B / A = 3 / 1

*October 9, 2016*

**Jar Marbles**

a) one of the five red marbles has the number 3 on it, so the probability is 1/5 b) two marbles have the number 1 on them, one red and one blue ... so the probability is 1/2

*October 9, 2016*

**Maths**

u = 2t - 6 10u + t = 10t + u + 9 substituting ... 20t - 60 + t = 10t + 2t - 6 + 9 solve for t, then substitute back to find u

*October 8, 2016*

**physics**

gravitational force follows an inverse-square relationship inverse of 1/8 is 8 ... 8 squared is 64

*October 8, 2016*

**math**

The Holy Father sent a courier from Rome to Venice, commanding him that he should reach Venice in 7 days. The most illustrious Signoria of Venice also sent another courier to Rome, who should reach Rome in 9 days. And from Rome to Venice is 250 miles. It happened that by the ...

*October 7, 2016*

**Physics**

the average velocity during braking ... (13.1 + 0) / 2 divide the stopping distance by the average velocity to find the time

*October 4, 2016*

**Math**

take out a common factor

*October 4, 2016*

**Algebra**

common factor 5x (x + 2)

*October 4, 2016*

**Chemistry**

the reaction equation is written in MOLES 2 moles NO plus 1 mole O2 yields ... 2 moles NO2 so 5 moles of O2 uses 10 moles of NO find the molar (formula) weight of NO, and multiply by 10

*October 4, 2016*

**Physics**

the delay time is down and back ... twice the depth

*October 4, 2016*

**Physics**

how about 4 by 2.9 ...

*October 4, 2016*

**Physics**

time = √(2 * distance / acceleration) initial velocity = 2 (distance / time)

*October 4, 2016*

**Chemistry**

there are about 55.3 moles of water in a liter the mean (average) concentration of chloride ions will be twice the arithmetic average of the MgCl2 concentrations (two Cl- for each MgCl2) I would be tempted to disregard the 175 value as a "flier"...but that's up ...

*October 4, 2016*

**Science Check my work PLS**

#8 ... a range of 5 in the 3rd digit is fairly precise the accuracy is substantially flawed

*October 4, 2016*

**Science**

a = f / m = 3 / 1

*October 4, 2016*

**physics**

the period is related to the mass and the spring constant the amplitude is inconsequential

*October 4, 2016*

**physics**

momentum is conserved the 2nd (larger) piece moves in the opposite direction at 1/3 the speed

*October 4, 2016*

**physics**

P = m g h / t = 100 * 10 * 6 / 120 answer is in Watts

*October 4, 2016*

**Calculus II**

If f(x) - x cos (x), how many intervals would be needed to approximate with the Trapezoidal Rule with an error of E<.01?

*October 3, 2016*

**Math 115**

a million is a thousand thousand (276.5 / 3150.4) thousand per mi^2

*October 2, 2016*

**Physics**

Tn = d / 40 Ts = d / 60 Save = 2d / (5d / 120)

*October 2, 2016*

**Physics**

.6 g = v^2 / r

*October 2, 2016*

**Calculus**

f(x) = x^2 has a critical point (and a MINIMUM) at x=0 f(x) = (x^3 + 3x^2 - 4x - 12) / (x+2) ... has a critical point (and a "hole" at x=-2)

*October 2, 2016*

**College math**

p(white) = 9/24 = 3/8 p(green) = 8/24 = 1/3 p(w then g) = 3/8 * 1/3

*October 1, 2016*

**Math (Condensing logarithmic expression)**

ln{5^2 * [x / (x^2 + 1)^2]^3}

*October 1, 2016*

**ACT math**

h + s = 10 ... s = 10 - h 12 h + 14 s = 128 substituting ... 12 h + 14(10 - h) = 128 ... 12 h + 140 - 14 h = 128 ... -2 h = -12

*October 1, 2016*

**Physics**

gravitational potential energy becomes kinetic energy m g h = 1/2 m v^2 v = √(2 g h) = √(2 * 9.81 * 15.0)

*October 1, 2016*

**Chemistry**

the sulfite ion has a -2 charge Pb(SO₃)₂ the hydrogen phosphate compound is missing a subscript 4 Pb(H₂PO₄)₄

*October 1, 2016*

**algebra 2**

3/5 (∛5)^2

*September 30, 2016*

**Physics**

compressing 0 cm to 6 cm is equivalent to compressing 0 cm to 3 cm, and continuing to compress 3 cm to 6 cm although the compression lengths are the same for the two parts, the 2nd part takes more work because the resistance of the spring increases with compression 0 to 6 uses...

*September 30, 2016*

**Calculus**

points with the same x or y coordinate represent vertical or horizontal chords of the circle the perpendicular bisectors of the chords are diameters, and they give one of the coordinates of the center you can use the distance formula to find the other coordinate of the center ...

*September 28, 2016*

**math**

you don't show any of the data, but it's very likely that the line doesn't go through the origin (0,0) there is probably some base rental charge (represented by the intercept)

*September 28, 2016*

**Chemistry**

E = m g h ... h = E / (m g) h = 628 kJ / (70 kg * 9.81 m/s^2) 1 Joule = 1 kg m/s^2

*September 28, 2016*

**Physics**

the ball is uniformly accelerated by gravity average velocity = ... (final vel. + initial vel.) / 2 6.5 m / 3.1 s = (V fin + 0) / 2

*September 28, 2016*

**Math (calculus 3)**

the given height equation is incorrect ... the t^2 coefficient is -16, not -8 solve away...

*September 28, 2016*

**MATH**

try again when the bases are the same, just add the exponents 3^2 x 3^2 = 9 x 9 = 81 = 3^4 ... not 9^4

*September 28, 2016*

**MATH**

try again when the bases are the same, just add the exponents

*September 28, 2016*

**help plzz asap**

the trains are closing at 110 mph ... (50 + 60) t = d / r = 330 mi / 110 mph

*September 28, 2016*

**Physics**

the .410 coefficient means that the max acceleration is .410 g

*September 28, 2016*

**Physics - EMERGENCY PLEASE HELP**

v^2 / r = 5 g r = v^2 / (5 g) r = (288 km/h)^2 / 49 m/s^2 r = (80 m/s)^2 / 49 m/s^2

*September 28, 2016*

**Math**

Oops forgot one step Ignore my first answer Step 1.)5*15=x Step 2.)x*5=Answer

*September 27, 2016*