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Posts by Scott

Total # Posts: 2,321

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

Geometry
1 + 2 + 3 is a straight angle (180º) 3 is a right angle (90º) 1 + 2 = 90 = x + x - 6 = 2 x - 6

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...

Math
1 + 2 + 3 is a straight angle (180º) 3 is a right angle (90º) 1 + 2 = 90 = x + x - 6 = 2 x - 6

MATHS
(120 / 2) √2 + 150

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)

Please Help
the smallest value for (X-5)² is zero so the range is any real number greater than or equal to 7

Algebra
they close the distance at 32 mph (128/4) x + x/3 = 4x / 3 = 32 mph

Math
they are separating at the rate of 125 mph s + s + 15 = 125 ... 2 s = 110

college algebra
no male non-smokers 17 smokers ... 5 female, 12 male 13 non-smokers, all female

math
3³ + 3 - (3/3)

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...

science
two quarts is four pints (4 * 30%) + (3 * 20%) = (4 + 3) * x

science
her mass is the same -- 24 kg her weight is 1/6 of her weight on earth

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

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

Physics
F = charge * velocity * field strength F = 2.76E-13 N

Physics
the normal force is equal to the gravitational force ... m g

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...

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

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

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

Chemistry
12.5 mM HCl and 7.5 mM KOH after netralization ... 5.0 mM HCl in 75.0 mL of solution ... .067 M HCl pH = -log[H⁺] = -log[.067]

Math
the amount of flour needed is directly proportional to the number of cakes...more cakes, more flour the constant of proportionality (k) is the flour per cake 4⅗ * k = 2/3 dividing both sides by 4⅔ k = 10/69 lb/cake seems more like a cupcake...

Science
yes

Physics
work is ... force times distance you have both ... 125 N , 45 m

Calculus
a b = 2 ... a = 2 / b s = a + b = 2/b + b ds = db (-2/b² + 1) ds/db = -2/b² + 1 = 0 b = √2 s = 2√2

Physics
your analysis looks okay your problem might be too many significant figures in your result

Biostatics
15.9% of the fish have lengths more than 1 standard deviation below the mean

Math
diagram?

Physics
the force constants add in parallel 16 N/m

Physics
1)as the elevator accelerates upward, the student's weight increases f = m a ... w = m a = m (g + e) 2)the elevator decellerates to a stop, so the student's weight is less than normal...same equations as #1 3)the greater the CHANGE in weight, the greater the ...

Physics
constant force means constant acceleration the graph is a flat line (zero slope)

Algebra
f(x) = 4 x - x²

mat
3 n + 4 = 15 / n 3 n² + 4 n - 15 = 0 (3 n - 5) (n + 3) = 0 n = 5/3 ... or ... n = -3

Science
1000 mL * .25 M = x mL * .75 M

Science
sulfuric is a binary acid [.56 / (2 * .25)] * .030 M

Physics
GPE = m * g * h = .6 * 9.81 * .3 J KE = GPE v = √(2 g h) m/s

Chemistry
D.

Science ~ Astronomy
not a ... we don't have the technology yet ... same for c b) ... computer modeling

Statistics
m - m ... 1/3 * 1/3 = 1/9 m - f ... 1/3 * 2/3 = 2/9 f - m ... 2/3 * 1/3 = 2/9 f - f ... 2/3 * 2/3 = 4/9 (i) 1/9 + 4/9 = 5/9 (ii) 2/9 + 2/9 = 4/9

physics
30 m/s / 1.5 m/s²

science
divide the mass of the zinc by its molar mass (65.4 g) to find the number of moles each mole of zinc will produce a mole of hydrogen gas (diatomic) multiply the moles by the molar mass of H₂ (2.02 g)

chemistry
44 g is one mole of propane so four moles of water are produced the molar mass of water is 18 g

math,algebra
L + C = 150 ... 75 L + 75 C = 150 * 75 40 L + 75 C = 7400 subtract the equations to eliminate C and solve for L

Science
find its mass (weigh it) then do like Archimedes and submerge the object to find its volume divide the mass by the volume

MATH
the radius, distance, and half the chord form a 5-12-13 triangle

MATH
the radius, half the chord, and the distance form a 3-4-5 triangle

chemistry
the sodium is the limiting reactant .6 moles

Math
[(76 - x) / 4]² + (x / 4)² = 205 76² - 152 x + x² + x² = 205 * 16 use the quadratic formula to find x either x or 76-x is shorter

math
s² < 6 s ... s < 6 any square with a side length less than 6

Chemistry
the estimated mass is to high (positive error) the amount is 10/240 ... A

chemistry
close ... D the decimal point makes the trailing zero significant

Math
when you connect the midpoints, the triangle formed is half the perimeter of the original triangle

gen chem
looking at the formula, there are two hydrogens for every carbon so ... 4.06x10^21 atoms of hydrogen there are 6 carbon atoms in each glucose molecule, so the number of molecules is ... 2.03x10^21 / 6

Math - Year 10 - Simult. Equations
o + t = 21 1 o + 2 t = 30 subtracting equations t = 9

Maths - Year 10 - Simult. Equations
50 f + 20 t = 310 f + t = 11 ... 20 f + 20 t = 220 subtracting equations (to eliminate t) 30 f = 90 ... f = 3 substitute back to find t

math
104² - 40² = x²

advanced science
net force is ... 1860 - 480 the acceleration is the net force divided by the mass significant figures appear to be a factor (Hint: there are two)

advanced science
the normal force is the force perpendicular to the load bearing surface...it is equal to the weight of the load on the surface in this case ... m * g the force is upward from the surface

physics
one

Physics - Doppler Effect
the frequency is lower, so the car is moving away from the listener 875/900 = (speed of sound) / ... (speed of sound + speed of car) they give you the temperature so that you can find the speed of sound (in air)

chemistry
.6 is correct ... due to H⁺ activity

math
law of cosines x² = 127² + 64² - [2 * 127 * 64 * cos(90º + 38º)]

Physics
answered yesterday

Chemistry
HCl totally dissociates, so the hydrogen ion concentration is .002 M pH = - log[H⁺] = - log(.002)

Chemistry
the volume increased by a factor of 2.5 the volume is directly proportional to the absolute (Kelvin) temperature ºK = ºC + 273

math
30 / 50 = 3 / 5

Physics
d = 1/2 a t²

physics
your distances from the speakers are different by a half wavelength (this is the reason for the sound "cancelling") 14 - 5 = 11 so the sound wavelength could be 22 ft

Physics
it takes ... 24 m/s / .65 m/s² to stop the average velocity is ... (24 + 0)/2 the stopping distance is the product of time and velocity

Physics
the component of the force that moves the crate (horizontal) is...the applied force, multiplied by the sine of the angle to the component 10N * sin(45º)

chem
the partial pressure is the total pressure, multiplied by the fraction of the gas involved in this case ...ppO = .32 * 132 atm ...ppN = (1 - .32) * 132 atm

SCIENCE
the 2nd one

PHYSICS
downward velocity at impact ... v = √(2 * 10 * 20) = 20 m/s upward velocity after impact ... v = √(2 * 10 * 15) = 10√3 m/s accel = Δv / t = (20 + 10√3) / .01 ...units are m/s²

College algebra
100 + 5 x = 103 + 4 x

Algebra
2.75 < 2.25 + (750 / p) < 3.75 .50 < 750 / p < 1.50 2 > p / 750 > 2/3 1500 > p > 500 none of the responses seem to be correct

age problems(please help)
S = 3s ... t = 5S = 15s t + 5 = 5(s + 5) = 5s + 25 3t + 15 = 15s + 75 substituting ... 3t + 15 = t + 75 solve for t

Physical Science
heat the ice to 0º melt the ice heat the water to 20º look up the heat of fusion for ice and the specific heats for ice and water

physics
the distance is closing, so the frequency is higher F = 50kHz * [1450 / (1450 m/s - 450 km/hr)]

Calc-Math
you need to use the product rule for xy x dy/dt + y dx/dt

Physics
its average speed while stopping is 30 mi/h there are 3600 sec in an hr , and 5280 ft in a mi d = 30 * 5280 * 6 / 3600 ... feet

Math
10 = 1/2 * g * t^2 20 / 9.8 = t^2

math
The area if a rectangle is x3y4. Which expression represents the length if the width is x2y

physics
C = Q / 100...100 C = Q capacitors add in parallel the charge is the same (redistributed) C + 10 = 100 C / 30 solve for C

Math
C. The answer is C, -7.

Math
It is impossible. 12, 14, or 16 may work, but I think you should give up on this equation...

Gen Chem
Thank you DrBob222!

Gen Chem
Knowing the MW of salicylic acid (138.12g/mol), design a procedure to make 100mL of a 0.0050M salicylic acid solution.

General Chemistry
That's why I was confused, it just states that the Fe(OH)3 has a solubility product of 10^-39. Any ideas?

Organic Chemistry
When I solve for Fe I get 1.75mL and for SYL I get 210mL. That can't be correct if we are trying to make 50mL. The equation is: Salicylic Acid + [Fe(H2o)6]^+3 ---> Iron-salicylate complex

Grade 12 Calculus and Vectors
Thank you very much Steve.

Grade 12 Calculus and Vectors
A homeowner wants to enclose a rectangular garden with fencing The garden will be adjacent to his neighbours lot. There will be fencing on all four sides. His neighbour will be paying for half of the shared fence. What should the dimensions of the garden be if the area is 432 ...

Pre-Calculus
Okay, what point is your origin? Normally it is (0,0) but not always...

Math
no C.

math
5C3 = 10

math
substituting -x + 13 = x² + 6 x + 7 0 = x² + 7 x - 6 none of the answers are correct

Math
.25 t = 1 t = 1 / .25

math
A - 25 = B + 25 ... A - 50 = B 7(B - 100) = 2(A + 100) ... 7 B - 700 = 2 A + 200 ... 7 B = 2 A + 900 substituting ... 7(A - 50) = 2 A + 900 ... 7 A - 350 = 2 A + 900 ... 5 A = 1250 ... A = 250

SCIENCE
pressure is force per unit area 100 N / 25 cm² = 4 N/cm² the SI pressure unit is the pascal 4 N/cm² = 40000 N/m² = 4 kPa

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