# 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