Monday

July 25, 2016
Total # Posts: 1,096

**Chemistry**

(360 / 180) moles / .200 L = 10 M
*July 2, 2016*

**Physics**

it appears to be a format problem 1/60 = 1.67E-2 rev/s
*July 1, 2016*

**Physics**

it takes 60 s for one revolution so it must be 1/60 r/s
*July 1, 2016*

**physics**

1.6 lb / .62 lb/ft
*July 1, 2016*

**physics**

1. the distance is ... 15 km + 10 km 2. the displacement is a vector from their starting point to their finishing point use Pythagoras and trig to find the distance and direction
*July 1, 2016*

**Chemistry**

sulphuric acid is diprotic (2 H⁺) so the normality is twice the molarity
*July 1, 2016*

**chemistry**

one part 50% HCl to four parts H₂O
*July 1, 2016*

**math**

what question?
*July 1, 2016*

**Math(HELP PLEASE )**

given table?
*July 1, 2016*

**math**

the (2,½) is correct not the same as (2 , 2/1) there is only one solution
*July 1, 2016*

**physics**

0 = ½ g t² + v₀ t + h 0 = -4.9 * 6² + 24 * 6 + h
*June 30, 2016*

**Physics**

V = √(2 g h) momentum is conserved ... .2 * V = (.2 + .4) v
*June 29, 2016*

**Calculus**

v = x (16 - 2x)² solve for the volume take the 1st derivative (dv/dx), and set equal to zero solve for x test the two solutions
*June 29, 2016*

**Math2**

the distance below the mean of Bob's pumpkin (z-score) is ... (938.23 - 1029.51) / 674.29 use a z-score table to find if the value lies in the upper 55.17% of entries looks like he just missed...
*June 29, 2016*

**Math( Assignment Due Today)**

h / Da = tan(35º) Da / 42 m = tan(30º) h = 42 m * tan(35º) * tan(30º)
*June 29, 2016*

**Physics**

gravity is providing the centripetal force (keeping the satellite on a circular path) a = v² / r you have a and r, just make the units consistent (a to km OR r to m)
*June 29, 2016*

**Physics**

a = (30 - 20) km/h / 1.5 s t = (36 - 30) km/h / a
*June 29, 2016*

**Physics**

answered
*June 29, 2016*

**math**

(1 - .04) * 1000 = (.25 + .05) * t
*June 28, 2016*

**Physics**

the radius of the Earth is ... 6371 km g (at the surface) is ... 9.81 m/s² (a) using the inverse-square relation ... a / g = (7000/6371)² (b) the velocity of the satellite is ... v² / r = a ... v = √(a²/r) ... keep the units consistent by converting a...
*June 28, 2016*

**Chemistry**

there is one mole of NaCl and two moles of H₂O
*June 28, 2016*

**Admaths**

constant distance from a point is a circle, centered at the point x = k is a vertical line, tangent to the circle so the radius of the circle is k-1 (x - 1)² + (y - 2)² = (k - 1)²
*June 28, 2016*

**math**

the store buys the items for some cost (c), and then marks up the selling price to 140% of c (cost plus profit) the 10% price reduction means that the sale price is 126% of c (140 - 14) the cost (c) doesn't change, so the profit is reduced to 26% (126 - 100)
*June 28, 2016*

**math**

14 N is half of 28 N, so it must be placed twice as far from the fulcrum for equilibrium 8 * 28 = d * 14
*June 27, 2016*

**mathemarics**

A. (17,12) B. d = √(20² + 16²)
*June 27, 2016*

**geometry**

2.) (3,-½)
*June 27, 2016*

**geometry**

8 units apart in the x-direction 3 units apart in the y-direction d = √(8² + 3²)
*June 27, 2016*

**Math**

it takes 600 man-hr to reap the field 600 / (8 * 15)
*June 26, 2016*

**chemistry**

how many pairs of electrons can be put into these orbitals? s -- 1 p -- 3 d -- 5 a degenerate orbital can hold a pair of electrons
*June 26, 2016*

**math**

v(x) = x (8 - 2x)(5 - 2x)
*June 26, 2016*

**Probability**

there are 24C2 ways of selecting two movies there are 9C2 ways of selecting two Barney movies the probability is ... 9C2 / 24C2
*June 25, 2016*

**Physics**

ave. velocity = (20 + 0) / 2 = 10 m/s .04 m / 10 m/s = .004 s
*June 25, 2016*

**math**

1.2 b + .9 b = 2.1 b 2.1 b / 2 b = 1.05 1.05 - 1 = .05 = 5% profit
*June 25, 2016*

**math**

f , s , t .6 t , .5 t , t .6 t / .5 t = 1.2 = 120%
*June 25, 2016*

**Algebra**

m = 37 h - 1500
*June 25, 2016*

**Physics**

one charge is attracting and the other is repelling the 3rd charge must be farther from the larger charge and not between the two charges remember inverse square law 7.25 / (d + 20)² = 2.00 / d² 7.25 d² = 2 d² + 80 d + 800 5.25 d² - 80 d - 800 = 0 use ...
*June 24, 2016*

**Chemistry**

the molar mass of NaCl is ... 58.44 g the molar mass of KI is ... 166.00 g
*June 24, 2016*

**Probability**

it's a binomial expansion (r + t)¹⁰ ... you want the 8th term 10C7 [(40/75)³ (35/75)⁷]
*June 24, 2016*

**Science**

wavelength = velocity / frequency λ = 3.0E10 cm/s / 6.0E18 hz
*June 24, 2016*

**Physics**

the s.a. of a sphere is ... 4 π r² or ... π d² km² = 1E6 m²
*June 23, 2016*

**math**

6497 , 5579 , 5993
*June 23, 2016*

**Math**

1.11 x = 5173
*June 23, 2016*

**Physics**

(a) f = m a = .02/32 * 1E5 = 63 lb (b) yes ... Newton's 3rd Law ... equal and opposite reaction (c) .007 s * 1E5 ft/s² = 700 ft/s sounds like an air rifle
*June 22, 2016*

**Physics**

the longest wavelength (lowest energy) would be from the 2nd excited state to the 3rd excited state
*June 22, 2016*

**Physics**

the plane must fly northeasterly so that its north velocity component equals the south velocity component of the wind 250 sin(Θ) = 50 sin(45º)
*June 22, 2016*

**Math**

the height of the satellite and the line through the stations form the right angle of a right triangle there are two hypotenuses (hypoteni?), one from each of the stations to the satellite curious as to how you found A) without the height h / a = tan(87º) h / (a + 35) = ...
*June 22, 2016*

**Physics**

v² / r = g sin(2Θ) / 2
*June 22, 2016*

**Physics**

u - u/20 = 19u/20 = .95u .95² = .9025 the bullet loses about 10% of its energy (kinetic), as work passing through the plank it should stop in the 11th plank
*June 22, 2016*

**Algebra**

salary = 1800 + (sales * .042) 4824 = 1800 + .042 s 3024 = .042 s
*June 21, 2016*

**Physical Science**

(6.38E6)² / .89 = (6.38E6 + h)²
*June 21, 2016*

**Physical Science**

h = ½ g t² ... .3 = ½ * 9.8 * t² t = √(.6 / 9.8) distance = 3.1 * t
*June 21, 2016*

**Mathematics**

almost ... 12/4 = 3 ... not 8 (not an exponent)
*June 21, 2016*

**statistics**

this is a binary expansion (h + t)⁴ the term you want is...6 h² t² 6 * (2/3)² * (1/3)² = 24/81 = 8/27
*June 21, 2016*

**Physical Science**

F = G * (m₁ m₂) / r² F = 6.7E-11 * 4.8E24 / (6.4E6)² N
*June 21, 2016*

**Math1(Please Help Me)**

A.) about 99% of a normally distributed population lies within 2½ standard deviations of the mean 159 cm ± (2½ * 5 cm) 65.9 kg ± (2½ * 12.7 kg) B.) the weight seems more variable because the s.d. is a larger fraction of the mean C.) 7 cm ...
*June 21, 2016*

**physics**

d = r * t (80 * t/2) + (40 * t/2) = 60 120 t = 120 ... t = 1 r = d / t = 60 km / 1 hr = 60 km/hr
*June 21, 2016*

**Math1**

A.) the data is clustered around a central value (mean), with fewer data points towards the edges B.) from statistical software ... mean = 195.5 , s.d. = 18.33 231 lbs is 1.94 s.d. above the mean [(231 - 195.5) / 18.33] this represents 2.6% of the population .026 * 218 = 5.67...
*June 20, 2016*

**Math**

2x² + 5x - 52 = 0 (2x + 13) (x - 4) = 0 x = 4
*June 20, 2016*

**Chemistry**

you need 7 moles of HCl for a complete reaction 7 moles / .85 M/L =
*June 20, 2016*

**algebra**

x = 5 is correct
*June 20, 2016*

**Math (pre-celc 12)**

you are correct
*June 20, 2016*

**Please Help Me!**

A.) the data is clustered around a central value (mean), with fewer data points towards the edges B.) from statistical software ... mean = 195.5 , s.d. = 18.33 231 lbs is 1.94 s.d. above the mean [(231 - 195.5) / 18.33] this represents 2.6% of the population .026 * 218 = 5.67...
*June 20, 2016*

**math**

3.54E7 m / 3.00E8 m/s = 1.18E-1 s
*June 20, 2016*

**Math**

60º is 1/6 of the circle a = [π (7/2)²] / 6
*June 20, 2016*

**math**

angle?
*June 20, 2016*

**math**

answered
*June 20, 2016*

**math**

the area of an isosceles right triangle is one half the square of the hypotenuse a = 3² / 2
*June 20, 2016*

**Math**

w = 250 m / tan(50º)
*June 19, 2016*

**Maths**

adding 6 ... 2 < 2x < 18 dividing by 2 ... 1 < x < 9 integers greater than 1 and less than 9
*June 19, 2016*

**Physical Science 8th Grade**

1. in a surface wave (like water); the water goes up and down, but the wave travels across (parallel to) the surface 2. energy is transferred 3. sound 4. c 5. parallel to (sound)
*June 19, 2016*

**Maths**

w = 250 m / tan(50º)
*June 19, 2016*

**Physics**

power is power...mechanical or electric...measured in Watts watt = Joule/s = volts * amps watt·sec = Joule kilowatt·hr = 3.6 MJ energy = energy
*June 19, 2016*

**math**

(59 - 3) / 4 = 14 14 + 1 = 15 terms
*June 19, 2016*

**Math**

z1 = 50 kg c2 = 150 kg t1 = 4/3 t2 4/3 t2 + t2 = 140 kg ... 7/3 t2 = 140 ... t2 = 60 kg ... t1 = 80 kg c1 = 200 kg - 50 kg - 80 kg = 70 kg c1 + c2 = 220 kg
*June 19, 2016*

**Math**

implicit differentiation 2 x dx/dt - 2 y dy/dt = 0 substituting [2*(-3)*(-4)] - [2*2*(dy/dt)] = 0
*June 18, 2016*

**Physics**

13 = -½ g t² + 24 t + 2 solve for t...there will be two solutions (up and down) the velocity is...v = 24 - g t ...use the up (smaller) time
*June 18, 2016*

**physic mechanic**

momentum is conserved .15 * 3.8 = 4.75 * v
*June 18, 2016*

**physical science**

momentum is conserved .16 * 25 = (85 + .16) * v
*June 17, 2016*

**Science : Physics**

balanced means zero net force Newton's 2nd law ... f = m * a if the force equals zero, then the acceleration also equals zero
*June 17, 2016*

**Geometry**

1 + 2 + 3 is a straight angle (180º) 3 is a right angle (90º) 1 + 2 = 90 = x + x - 6 = 2 x - 6
*June 17, 2016*

**Science : Physics**

the work done in stopping is... f * d ... 60 * 26.3 = ? J the work equals the initial kinetic energy of the object... ½ m v² 60 * 26.3 = ½ * 15 * v² v = √(8 * 26.3) m/s be aware of significant figures...
*June 17, 2016*

**Math**

1 + 2 + 3 is a straight angle (180º) 3 is a right angle (90º) 1 + 2 = 90 = x + x - 6 = 2 x - 6
*June 17, 2016*

**MATHS**

(120 / 2) √2 + 150
*June 17, 2016*

**math**

a) use fooplot dot com b) 4 ft c) set h=0 , then solve for t d) set h=30 , then solve for t ... two solutions e) never f) axis of sym ... 50 / (2 * 16) g) use value from f) in h(t)
*June 16, 2016*

**Please Help**

the smallest value for (X-5)² is zero so the range is any real number greater than or equal to 7
*June 15, 2016*

**Algebra**

they close the distance at 32 mph (128/4) x + x/3 = 4x / 3 = 32 mph
*June 15, 2016*

**Math**

they are separating at the rate of 125 mph s + s + 15 = 125 ... 2 s = 110
*June 15, 2016*

**college algebra**

no male non-smokers 17 smokers ... 5 female, 12 male 13 non-smokers, all female
*June 15, 2016*

**math**

3³ + 3 - (3/3)
*June 15, 2016*

**Physics**

his energy (gravitational) is ... m g (h+d) = 45 * 9.8 * (7+d) the depth (d) he reaches is based on the work done by the water ... w = f d = 1500 d 1500 d = 45 * 9.8 * (7+d) f = m a ... a = f / m his deceleration is the net force (gravity minus water) divided by his mass a...
*June 15, 2016*

**science**

two quarts is four pints (4 * 30%) + (3 * 20%) = (4 + 3) * x
*June 15, 2016*

**science**

her mass is the same -- 24 kg her weight is 1/6 of her weight on earth
*June 15, 2016*

**maths**

a) v = ⅓ π r² h = 16 π b) the radius of the circle is 5 cm ... √[(8/2)² + 3²] = 5 Θ = 2 π * 8 / 10
*June 15, 2016*

**Maths**

the ladder, wall, and ground form a Pythagorean triple (like 3-4-5) this one is 5-12-13
*June 13, 2016*

**Physics**

F = charge * velocity * field strength F = 2.76E-13 N
*June 13, 2016*

**Physics**

the normal force is equal to the gravitational force ... m g
*June 13, 2016*

**Maths**

12 pens out of 40 are neither red nor green a randomly selected pen has a 12/40 or .3 probability of being in this group not sure where 3/4 comes from...
*June 13, 2016*

**Algebra**

a negative number, multiplied an odd number of times, is still negative no real number, multiplied an even number of times, can be still negative pos times pos is pos neg times neg is pos
*June 13, 2016*

**Physics I (Classical)**

for b) and c), determine the force (Q) using the acceleration components and the components of (P) ... you have the mass of the block f = m a ... by components
*June 13, 2016*

**Engineering science**

distance up equals distance down time up equals time down 3.5 s to peak g = 9.8 m/s² average velocity = (3.5 * 9.8) / 2 total distance = (ave vel) * 7
*June 12, 2016*