Tuesday

September 27, 2016
Total # Posts: 1,262

**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

*June 3, 2016*

**math**

104² - 40² = x²

*June 3, 2016*

**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)

*June 3, 2016*

**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

*June 3, 2016*

**physics**

one

*June 3, 2016*

**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)

*June 2, 2016*

**chemistry**

.6 is correct ... due to H⁺ activity

*June 2, 2016*

**math**

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

*June 1, 2016*

**Physics**

answered yesterday

*June 1, 2016*

**Chemistry**

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

*June 1, 2016*

**Chemistry**

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

*May 31, 2016*

**math**

30 / 50 = 3 / 5

*May 31, 2016*

**Physics**

d = 1/2 a t²

*May 31, 2016*

**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

*May 31, 2016*

**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

*May 31, 2016*

**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)

*May 31, 2016*

**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

*May 30, 2016*

**SCIENCE**

the 2nd one

*May 28, 2016*

**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

*May 28, 2016*

**College algebra**

100 + 5 x = 103 + 4 x

*May 26, 2016*

**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

*May 26, 2016*

**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

*May 25, 2016*

**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

*May 25, 2016*

**physics**

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

*May 25, 2016*

**Calc-Math**

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

*May 24, 2016*

**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

*May 24, 2016*

**Math**

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

*May 24, 2016*

**math**

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

*May 24, 2016*

**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

*May 24, 2016*

**Math**

C. The answer is C, -7.

*May 24, 2016*

**Math**

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

*May 24, 2016*

**Gen Chem**

Thank you DrBob222!

*May 20, 2016*

**Gen Chem**

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

*May 20, 2016*

**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?

*May 20, 2016*

**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

*May 20, 2016*

**Grade 12 Calculus and Vectors**

Thank you very much Steve.

*May 17, 2016*

**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 ...

*May 17, 2016*

**Pre-Calculus**

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

*May 17, 2016*

**Math**

no C.

*May 14, 2016*

**math**

5C3 = 10

*May 14, 2016*

**math**

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

*May 14, 2016*

**Math**

.25 t = 1 t = 1 / .25

*May 14, 2016*

**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

*May 14, 2016*

**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

*May 14, 2016*

**Maths -Logarithm**

3^3 = 27 log(x) = 27 log(3) x = 10^[log(x)]

*May 14, 2016*

**geometry**

hard to tell without the diagram

*May 14, 2016*

**algebra**

(a) 37% / 60% (b) 37% / 52%

*May 7, 2016*

**Physics**

momentum is conserved m bt * v bt = (m bt + m bk) * v bkbt h = ½ g t² ... 1.3 = 4.9 t² ... t = .52 s v bkbt = d / t = 2.2 m / .52 s ... v bkbt = 4.2 m/s 7 * v bt = 131 * 4.2

*May 7, 2016*

**probability help!!**

all wait times have an equal probability so the probability of being in any one of three five-minute intervals is ⅓ (a) is the 1st interval (b) is the last interval

*May 7, 2016*

**Math**

the slant height is the height of the triangles that make up the sides of the pyramid the base of the triangles is the base side length pentagonal means five triangular sides with a height of 18 and a base of 9 find the areas and add them up (or find one and multiply by 5)

*May 6, 2016*

**math**

a = 6350 [1 + (.14 / 2)]^[12 / (1/2)]

*April 19, 2016*

**physics**

the acceleration is ... 2 m/s / 14 s = .14 m/s² as the car goes up a slope, the gravitational acceleration on the car is proportional to the sine of the angle of the slope sin(Θ) = .14 m/s² / 9.8 m/s² = .014 Θ = 0.8º

*April 19, 2016*

**Math**

Given function 3x/x^2-x-12 sub in -1 for x. I get the value x=0.3. Is that right?

*April 16, 2016*

**ph science**

work = 64 N * cos(35º) * 45 m

*April 16, 2016*

**Physics **

A 0.11-kg balloon is filled with helium (density = 0.179 kg/m3). If the balloon is a sphere with a radius of 5.4 m, what is the maximum weight it can lift?

*March 28, 2016*

**Algebra**

A man paid $7.80 for 5 The grams of peanuts and 3 kg of walnuts. Walnuts are $.20 a kilogram more than peanuts how much did she pay per kilogram for each

*March 21, 2016*

**home school**

In which of the following are 1/2,5/6, and 5/8 arranged in ascending order?

*March 13, 2016*

**Math Question**

Write the fraction below as a decimal. 7 --- = 100

*March 8, 2016*

**phy 231**

at the equilibrium position, there is no energy stored in the spring, it's all in the kinetic energy of the block KE = 1/2 m v²

*March 8, 2016*

**Physics**

vertical ... 2[5 sin(θ)] / g = t ... h = 5/2 sin(θ) * t/2 horizontal ... d = 5 cos(θ) t 2h = d 5/2 sin(θ) t = 5 cos(θ) t dividing by cos(θ) t and multiplying by 2/5 tan(θ) = 2 substitute back to find t

*March 7, 2016*

**Physics**

time up equals time down flight time = 2 * 30 m/s / 10 m/s²

*March 7, 2016*

**Physics**

there are 3600 s in an hr 180 km/h = 50 m/s the average velocity during the stop is ... (50 + 0) / 2 the stopping distance is ... 25 m/s * 20 s

*March 7, 2016*

**Physics**

gravity decelerates the ball time to peak is ... 30 / 9.8 the velocity at peak is zero, so the average velocity is ... (30 + 0) / 2 peak height is average velocity, multiplied by time

*March 7, 2016*

**Physics**

it's a 3-4-5 triangle 600-800-?

*March 7, 2016*

**Math**

If a pie was cut into sixths and one cut into eighths how many pieces are there altogether?

*March 5, 2016*

**Statistics**

the upper 15% of weights are a little over one S.D. above the mean so, more than ... 764 + 33 using a z-score table ... 1.036 S.D so, more than ... 764 + (33 * 1.036)

*February 29, 2016*

**Chemistry**

-log[H⁺] = 5.42 ... [H⁺] = 10^-5.42 = 3.80E-6 Ka = [H⁺][A⁻] / [HA] ... = 3.80E-6 * 3.80E-6 / ... (.095 - 3.80E-6) ... = ?

*February 29, 2016*

**Science**

electricity

*February 29, 2016*

**Physics**

momentum = m v = .057 * 29 the units are kg·m/s

*February 25, 2016*

**Algebra**

completing the square (16 / 2)² = 64 (x + 8)²

*February 25, 2016*

**Chemistry 101**

400 T * 1.0 oz/T * $1625 / oz

*February 25, 2016*

**Math**

s^2 = (6/2)^2 + 5^2 pick another letter

*February 24, 2016*

**Geometry**

factor the numerator [n * (n + 1)] / 4 n cancel the n in the numerator and denominator (n + 1) / 4

*February 24, 2016*

**physics**

conservation of momentum (again) (2300 + 1290) * 4800 = (1290 * 5600) + (2300 * v)

*February 23, 2016*

**physics**

momentum is conserved (a) 98 * 3.2 = 235 * -v (b) 98 * 3.2 = (98 + 235) * v

*February 23, 2016*

**Algebra 2**

you have the hypotenuse and the side lengths use trig functions to find the two unknown angles (A and B) S-O-H-C-A-H-T-O-A

*February 23, 2016*

**MATHS**

7 P + 22 = 2 (5 P + 2) 7 P + 22 = 10 P + 4 18 = 3 P

*February 23, 2016*

**STATISTIC**

you are right

*February 23, 2016*

**Physics**

the car is overtaking the truck the relative speed is 30 mph ... the distance is closing ... that's why the Doppler frequency is higher apparent frequency = actual frequency * [(speed of sound) / (speed of sound - closing speed)]

*February 23, 2016*

**physics**

f = m a μ m g = m (d / t²) μ = (d / t²) / g = (1320 / 6²) / 32 the assumption is that all of the mass acts on the driving wheels

*February 22, 2016*

**math **

Solve for all real values of y: |3y+7|=|2y-1|.

*February 21, 2016*

**physics**

when it leaves the roof vertical velocity ... -7.00 sin(40º) horizontal velocity ... 7.00 cos(40º) the horizontal velocity is constant the vertical velocity is increased by gravity (acceleration) h = -1/2 g t² + v₀ t + h₀ ... t is the time of flight ...

*February 21, 2016*

**physics**

m g h = 1/2 m v² h = v² / (2 g)

*February 20, 2016*

**Physics**

the drop height is ... 1/2 g t² the times are ... 4 s ... and (4 - 2.34) s g is ... 9.81 m/s² fire up that calculator

*February 20, 2016*

**Trig**

a road is inclined at an angle of 45degrees. After driving 300 feet along this road, find the driver's increase in altitude.

*February 19, 2016*

**Ms. Sue, please help me on math!**

they are both correct

*February 18, 2016*

**Physics**

an Ampere is a Coulomb per second a Coulomb is the charge on 6.242 x 10¹⁸ electrons there are 3600 seconds in an hour .497 * 6.242E18 * 3.6E3 = answer

*February 18, 2016*

**Algebra**

they each do a fraction of the job the fractions add to one the whole job (2.2 / T) + (2.2 / J) = 1 substituting [2.2 / (J + 2)] + (2.2 / J) = 1 solve for J, add 2 to find T

*February 18, 2016*

**Chemistry**

yes, but they give you the wavelength e = h c / λ make sure your units are consistent

*February 18, 2016*

**Chemistry**

2 moles of Al to 3 moles Cl₂ use the molar masses to find the number of moles

*February 18, 2016*

**physics**

the decimal point on the mass units is incorrect Joules uses kilograms, not grams you used kg in the momentum, but not the K

*February 17, 2016*

**Physics**

in the vertical direction ... h = 1/2 g t^2 + 59 sin(32º) t in the horizontal direction ... d = 59 cos(32º) t use the axis of symmetry of the parabola to find the time for max height plug the time into the vertical equation to find the max height the initial energy ...

*February 17, 2016*

**physics**

momentum is conserved 71 * 2.5 = 59 * v the direction is negative x

*February 17, 2016*

**chemistry**

the molar mass of water is 18.0 g E = [25 * (100 - 25) * .00418] + ... [(25 / 18) * 40.6]

*February 17, 2016*

**science, chemistry**

100.0 mL * 12.0 M = v * 5.20 M

*February 17, 2016*

**Math**

7 * 1/12

*February 17, 2016*

**6th grade math median range mode**

if all the values occur equally, there is no mode

*February 17, 2016*

**Physics**

the acceleration is ... (5.31 - 1.25) / 1.05 the sine of the angle of inclination is equal to the actual acceleration divided by gravitational acceleration sin(Θ) = [(5.31 - 1.25) / 1.05] / g

*February 17, 2016*

**Algebra**

z + t + c = 1000 t = 2 z c = 15 t + 10 = 30 z + 10 z + 2z + 30z + 10 = 1000 solve for z, then substitute back to find c and t

*February 17, 2016*

**Chemisty**

a mole is Avogadro's number ... 6.02 x 10^23 so you need the mass of a third of a mole of F₂ the molar mass of F₂ is 38 g

*February 17, 2016*