# R_scott

Popular questions and responses by R_scott-
## Chemistry

volume is directly proportional to the absolute (Kelvin) temperature and inversely proportional to the pressure v = 20 L * [(new temp.) / (old temp.)] * [(old press.) / (new press.)]

*posted on July 1, 2020* -
## Physics

...teach the group?? the range is ... R = [v^2 * sin(2Θ)] / g ... v is the launch velocity ... 200 m/s ... Θ is the launch angle ... 30º

*posted on July 1, 2020* -
## Mathematics

each team will play four games...one with each of the four other teams there are ten games in total ... five teams each playing four games ... 5 * 4 = 20 ... but ...A playing B is the same as B playing A ... so ... 20 / 2 = 10

*posted on June 30, 2020* -
## Mathematics.

volume is, the area of the cross-section, multiplied by the length v = [π * 3.5 cm)^2] * 8 cm

*posted on June 29, 2020* -
## math

the two dice are independent events ... the probability of both occurring ... is the product (multiply) of the individual probabilities p = (6 / 26) * (3 / 12) remember to reduce fractions where possible

*posted on June 29, 2020* -
## physics

momentum is conserved .125 kg * 25.0 m/s = (.125 kg + .101 kg) * v solve for the horizontal velocity (v) of the arrow/apple the flight time of the arrow/apple is the time it takes to fall 1.85 m 1.85 = 1/2 g t^2 ... solve for the flight time (t) the

*posted on June 29, 2020* -
## Math

if the bases are the same , you can add the exponents (2/9)^3 × (2/9)^(-6) = (2/9)^(3-6) = (2/9)^(-3) (2/9)^(-3) = (2/9)^(2m - 1)

*posted on June 29, 2020* -
## Physics

Δh = [1/2 * (-9.81 m/s^2) * (2.00 s)^2] - (15.0 m/s * 2.00 m)

*posted on June 26, 2020* -
## Physics

11.26 m = 1/2 * g * (3.17 s)^2

*posted on June 26, 2020* -
## Physics

h = [1/2 * (-9.81 m/s^2) * (0.250 s)^2] + (.250 s * 5.00 m/s) + 40.0 m

*posted on June 26, 2020* -
## Physics

the accelerations are the same the velocities are different

*posted on June 26, 2020* -
## math

the sides are unchanged

*posted on June 26, 2020* -
## math

if two cups is one pint , how many pints is five cups?

*posted on June 25, 2020* -
## Physics

20 * 377 * (200 - t) = [(50 * 4190) + (60 * 377)] * (t - 30)

*posted on June 25, 2020* -
## geometry

the radius of the base is ... 18 cm * (300º / 360º)

*posted on June 25, 2020* -
## math

8 oz = 1 C 2 C = 1 pt 2 pt = 1 qt 4 qt = 1 gal

*posted on June 25, 2020* -
## mathematics

the parabola ... y = x^2 the line ... y = 2 x + 3

*posted on June 25, 2020* -
## math

56 kg * 9.8 m/s^2 * 1.0 m / 1.4 s = ? Watts

*posted on June 25, 2020* -
## geometry

yup

*posted on June 25, 2020* -
## Probability

$65k is 1.2 s.d. above the mean use a z-score table to find the % (probability) this represents

*posted on June 24, 2020* -
## math

(s + 6) * 2 = 26

*posted on June 24, 2020* -
## science

balancing ... 2 HCI + Na2CO3 = 2 NaCI + H20 + CO2

*posted on June 24, 2020* -
## Physics

mass of the block = volume * density force (weight) = m * g pressure = force / area ... newton per m^2 is a Pascal max pressure when resting on smallest side ... 1.2 m x 1.0 m min pressure when resting on largest side ... 1.2 m x 1.5 m

*posted on June 24, 2020* -
## Physics

power = work / time = m g h / t = 75 kg * 9.8 m/s^2 * 12 * .20 m / 10 s = ? W

*posted on June 24, 2020* -
## Physics

the platform height is one significant figure all of the responses are at least two significant figures

*posted on June 23, 2020* -
## Math

taking natural log ... x ln(10) = ln(2) + 1

*posted on June 22, 2020* -
## Mathematics

sin(B) / sin(A) = b / a C = 180º - A - B c = b * sin(C) / sin(B)

*posted on June 21, 2020* -
## geometry

joining the midpoints means that the smaller triangle is half the height ... and half the base length of the larger triangle use the triangle area formula to find the relationship k * [1/2 * (b/2) * (h/2)] = 1/2 * b * h ... solve for k

*posted on June 18, 2020* -
## Math

5.4% is lost to leakage ... so (100% - 5.4%) remains in the tank 1500 L * (100% - 5.4%) = ?

*posted on June 18, 2020* -
## Physics

a. the work is equal to the initial kinetic energy of the block ... K.E. = 1/2 m v^2 = 1/2 * 4.0 kg * (6.0 m/s)^2 = ? Joules b. work = force * distance ... distance = (answer a.) / 88 N = ? m

*posted on June 18, 2020* -
## Math

find f(x) for the values at the ends of the interval divide the difference in the f(x) values by the difference in the x values

*posted on June 18, 2020* -
## Physics

2E4 C/s * 1E-4 s = ? C ? C / 1.6E-19 C/e = ? e

*posted on June 18, 2020* -
## Math

use the quadratic formula to find the roots of the 1st equation then plug the numbers into the 2nd question

*posted on June 18, 2020* -
## Math

$20 * .06 * 2000

*posted on June 17, 2020* -
## Physics

1. yes ... 250 J is correct 2. kinetic energy = work ... 1/2 * m * v^2 = f * d ... find the work , then solve for the velocity ... 5 m/s seems correct ... maybe a significant figure issue? 3. similar to #2 ... work on the rocket is "net force" multiplied

*posted on June 17, 2020* -
## Calculus

(a) differentiating ... f'(x) = -0.2 x - 0.7 (b) to find dp/dx , plug x=3 into f'(x)

*posted on June 17, 2020* -
## mathematics

5% semiannually means 2.5% per compounding period balance = 500 * [1 + (2.5%)]^(6 * 2) b = 500 * (1.025)^12

*posted on June 16, 2020* -
## Mathematics

18 hr : 48 hr 18 / 48 = 3 / 8

*posted on June 16, 2020* -
## math

the coordinates are in alphabetical order ... x , y no +2 y-coordinate in the list

*posted on June 16, 2020* -
## mathematics

t / 1.8 cm = 84 / 350

*posted on June 16, 2020* -
## mathematics

x - 3 = k y^2 5 - 3 = 4 k ... k = 1/2 x - 3 = 1/2 * 6^2

*posted on June 16, 2020* -
## Physics

the center of mass of the rule is at the 25 cm mark 40 g * (15 cm - 2 cm) = M * (25 cm - 15 cm)

*posted on June 16, 2020* -
## Math

3rd and 4th days ... 18 km + 18 km = 36 km 36 km = 3/4 d after 1st day ... d = 48 km 48 km = 2/3 total d ... total d = 72 km G = 3 S G - 5 = 2 (S + 5) ... G = 2 S + 15

*posted on June 16, 2020* -
## Mathematics

tan(Θ) = 120 / 400

*posted on June 16, 2020* -
## mathematics

if r is a root (zero) , then x-r is a factor complex roots (containing i) occur in conjugate pairs ... if 2+2i is a root , then 2-2i is also P(x) = (x - 2 - 2i) (x - 2 + 2i) (x + 1) (x - 2) multiply the factors to find the 4th order function

*posted on June 15, 2020* -
## Chemistry

moles H2SO4 = 10 g / (molar mass H2SO4) moles H2O = 20 g / (molar mass H2O) mole fraction H2SO4 = moles H2SO4 / (moles H2SO4 + moles H2O)

*posted on June 15, 2020* -
## Trigonometry

distance between the exits is ... d1 = 81 km - 74 km road distance from balloon to x-81 ... d2 = 875.0 m / tan(11º) road distance to x-74 ... d3 = d1 - d2 angle of depression to x-74 ... tan(Θ) = 875.0 m / d3

*posted on June 15, 2020* -
## Math

sin^2(θ) = 3 / 4 ... sin(θ) = ±√3 / 2

*posted on June 15, 2020* -
## math

n-2 , n-1 , n , n+1 , n+2 , n+3 6 n + 3 = 519

*posted on June 14, 2020* -
## trigonometry

the downhill angle of the fence is 110º ... 90º + 20º using the law of sines ... sin(Θ) / 2.5 = sin(110º) / 6.3

*posted on June 14, 2020* -
## mathematics

oobleck is correct

*posted on June 14, 2020* -
## mathematics

tan(Θ) = 2.1 / 15.9

*posted on June 14, 2020* -
## Physics

heat = mass * specific heat * temperature change 25 * x * (100. - 27.5) = 85 * 4.19 j/g⋅ºC * (27.5 - 25.0)

*posted on June 14, 2020* -
## Algebra

guessing a pie with a piece missing the outside circular perimeter is 5/6 of the circumference ... 5/6 * π * 2 * 7 the inside perimeter of the mouth is 2 radii ... 2 * 7

*posted on June 13, 2020* -
## Chemistry

sample volume * molarity = moles .0284 L * 0.185 moles/L = ? moles

*posted on June 11, 2020* -
## Chemistry

to find the moles of glucose in 54.30 g , divide by the molar mass

*posted on June 11, 2020* -
## Math

2k + 8k + 10k = 180º ... k = 9º smallest angle is 2k

*posted on June 11, 2020* -
## Math

the general circle equation is ... (x - h)^2 + (y - k)^2 = r^2 (h,k) is the center of the circle , r is the radius the equations of the two points should NOT be equal ... and they should have the correct format

*posted on June 11, 2020* -
## Physics

work = force * distance 1210 = f * 20.0 ... f = 60.5 N 60.5 N = 75 N * cos(Θ)

*posted on June 11, 2020* -
## Physics

the work (energy) is the difference in kinetic energy at the two speeds work = 1/2 (62 kg + 12 kg) * [(12.7 m/s)^2 - (8.2 m/s)^2] ... Joules

*posted on June 11, 2020* -
## Math

gradient is also known as slope ... the change in y, divided by the change in x the general slope-intercept equation is ... y = m x + b ... m is the slope , and b is the y-intercept (where the line crosses the y-axis) solving the given equation for y ...

*posted on June 11, 2020* -
## mathematics

divide by e^(kt) ... y / [e^(kt)] = y0

*posted on June 8, 2020* -
## Physics

the ultraviolet end of the spectrum is higher energy than the infrared

*posted on June 8, 2020* -
## Physics

the weight (force) of a 3.15 kg mass is ... 3.15 * g find the spring constant (k) by dividing the force by the extension ... (3.15 * g) / (13.40 cm - 12.00 cm) stored energy is ... 1/2 * k * x^2 ... find x ... add it to 12 for Joules , the extension is in

*posted on June 8, 2020* -
## Science

distance and orbital velocity are inversely related the area of the orbital ellipse swept by a planet is a constant

*posted on June 7, 2020* -
## Mathematics

draw the diagram and use the law of sines

*posted on June 7, 2020* -
## Math

π * d * h ... is the lateral surface area

*posted on June 7, 2020* -
## algebra

q - 17

*posted on June 6, 2020* -
## Maths

7 * 5 = 35 ... man-days to dig hole half a hole takes 35/2 man-days (35/2) / 3 = 35/6 man-days for half a hole ... almost six days

*posted on June 5, 2020* -
## mathematics

40 * (1 - .20) * (1 + .05)

*posted on June 4, 2020* -
## mathematics

how many ways can you get 8? 6-2 ,5-3 , 4-4 , 3-5 , 2-6 there are 36 possible outcomes ... 6 sides * 6 sides

*posted on June 4, 2020* -
## science

electrostatic force is an inverse-square relation 6.0 / d^2 = 15 /(2.0 - d)^2 solve for d 15 d^2 = 24 - 24 d + 6 d^2 9 d^2 + 24 d - 24 = 0 ... 3 d^2 + 8 d - 8 = 0

*posted on June 4, 2020* -
## Physics

the ramp (frictionless) is a longer distance, but a lower effort (force) the work is the same

*posted on June 4, 2020* -
## Physics

the gravitational force is constant over this short distance the change in gravitational potential energy (work) is ... m * g * h ... the work is negative (against gravity) FYI ... technically, the answer sig fig is the smallest of the input data ... the

*posted on June 4, 2020* -
## Physics

how big is the loop?

*posted on June 4, 2020* -
## Mathematics

(105º / 360º) * 2 * 6 cm * 22/7

*posted on June 4, 2020* -
## Math

the 7 rounds up to 10 ... 1010

*posted on June 3, 2020* -
## Chemistry

3970 g / 7.86 g/mL = ? mL 100 mL = 1 dL

*posted on June 3, 2020* -
## algebra

angle + complement = 90º

*posted on June 3, 2020* -
## physics

5.00E2 N * cos(29º) * 20 m = ? Joules

*posted on June 3, 2020* -
## Physics

the centripetal force (tension in the string) ... keeps the ball moving in a circle the force necessary is ... m v^2 / r = .167 * 4.9^2 / .98 ... Newtons ... this is the tension at the sides of the circle at the top and bottom of the circle ... the weight

*posted on June 3, 2020* -
## physics

m * g * h / t = 32 kW ... m * g * h / 32 kW = t ... seconds

*posted on June 3, 2020* -
## Maths

let x = 3^n x^2 + 1 - (4 x + 4 + 9) = 0 ... x^2 - 4 x - 12 = 0 (x - 6) (x + 2) = 0 ... x = 6 , x = -2 3^n = 6 ... 3^n = -2 is an impossible solution n log(3) = log(6)

*posted on June 3, 2020* -
## physics

time = distance / rate 8 km / v = 9 km / (v + 2) multiplying by [v ( + 2)] ... 8 v + 16 = 9 v speeds are ... 16 kph and 18 kph convert to m/s ... multiply by 1000 m/km and divide by 3600 s/hr

*posted on June 3, 2020* -
## Mathematics

6 * 5/8 = ?

*posted on June 3, 2020* -
## Physics

see Bill at 6:58 yesterday

*posted on June 3, 2020* -
## Physics

your mass is ... 588 / g the force (391 N) accelerates your mass for 0.576 s find the acceleration ... f = m a ... a = f / m find the distance during acceleration ... d = 1/2 a t^2 find your final velocity ... v = a t time to shore = acceleration time +

*posted on June 2, 2020* -
## Algebra

s equals zero on the ground 0 = −16t2 + 2120 16t2 = 2120 ... t^2 = 132.5 ... this is the SQUARE of the time take the square root to find the fall time

*posted on June 2, 2020* -
## Algebra

the max is on the axis of symmetry of the parabola x = -b / 2 a = -10 / (2 * -5) = 1 1 second up, one second down ... 2 sec flight time plug one into the original equation to find max height

*posted on June 2, 2020* -
## math

D time = distance / rate = 20 km / 10 kph = 2 hr M has covered ... 20 km - 4 km = 16 km ... in 2 hr ... 16 km / 2 hr = 8 kph M has 4 km to go ... 4 km / 8 kph = 1/2 hr

*posted on June 1, 2020* -
## Physical Science

m * g * Δh = 80 kg * 9.8 m/s^2 * (700 m - 400 m) = ? Joules

*posted on June 1, 2020* -
## PreCalculus

these identities are helpful cos(u) = 1 / sec(u) cos(u/2) = ± √{[1 + cos(u)] / 2} cos(u/2) = ± √({1 + [1 / sec(u)]} / 2)

*posted on June 1, 2020* -
## Mathematics

h + t + u = 6 h = 2 u t = h + u ... 2 t = 6 ... t = 3 h + u = 3 ... 3 u = 3 ... u = 1 h + 3 + 1 = 6 ... h = 2

*posted on May 30, 2020* -
## Algebra

p^4 + 4 p^3 q + 6 p^2 q^2 + 4 p q^3 + q^4

*posted on May 29, 2020* -
## physics

hz = cycles / seconds

*posted on May 29, 2020* -
## physics

looks good

*posted on May 29, 2020* -
## science

bingo

*posted on May 29, 2020* -
## science

how are plant cells different from animal cells?

*posted on May 29, 2020* -
## Algebra

4000 * e^(rt) 4000 * e^.328

*posted on May 29, 2020*