# R_scott

Newest questions and responses by R_scott-
## Maths

change km/hr to m/s find how long for the train to pass a given point ... t length of bridge = (12 - t) * speed of train

*posted on January 16, 2019* -
## Maths

close, but ... 14 cm is the RADIUS of the cylinder, ... while 4 mm is the DIAMETER of the wire 14^2 * 10 = (0.4 / 2)^2 * x

*posted on January 16, 2019* -
## Algebra repost

oobleck ... and if x happens to be negative...?

*posted on January 16, 2019* -
## Algebra repost

n > 4

*posted on January 16, 2019* -
## Science

you are correct a temperature differential is necessary for heat transfer

*posted on January 16, 2019* -
## math

12 compoundings (two per year) 4.5% per compounding A = 18000 (1 + .045)^12

*posted on January 16, 2019* -
## math

3.4E9 in scientific notation

*posted on January 15, 2019* -
## Physics

p v = n r t you can see from the gas equation that pressure and volume are inversely related like the graph of x y = constant

*posted on January 14, 2019* -
## algebra

solve the given equation for h rearranging and simplifying ... 0 = h^2 + 2 h - 99 factor or use the quadratic formula

*posted on January 14, 2019* -
## math

principal * interest rate * years

*posted on January 14, 2019* -
## Math

1" / 280' = x" / 756'

*posted on January 14, 2019* -
## chemistry

it is a constant ... like specific heat ... look it up

*posted on January 14, 2019* -
## chemistry

heat the ice to 0ºC ... specific heat of ice? melt the ice to water at 0ºC ... heat of fusion of ice?

*posted on January 14, 2019* -
## physics

you're correct Newton's equal and opposite reactive force

*posted on January 14, 2019* -
## Physics

b) impulse is the change in momentum ... final minus initial ... look at your deltav value ... velocity is a vector ... magnitude AND direction this should also "fix" c)

*posted on January 13, 2019* -
## math

12 n = n^2 + 36 0 = n^2 - 12 n + 36 = (n - 6)^2 n - 6 = 0

*posted on January 12, 2019* -
## Physics

a = f / m divide the initial velocity by the acceleration to find the stopping time

*posted on January 11, 2019* -
## Physical Science

both silk and rubber attract electrons from glass rubber attracts electrons from silk , so it has the strongest attraction

*posted on January 11, 2019* -
## Maths

each of the four aces is combined with four of the other 48 cards 4 * 48C4

*posted on January 11, 2019* -
## Math

nine total points below average , so nine total above Don scored four points above average ... Cara outscored him by one point ... 29

*posted on January 11, 2019* -
## Physics

a. v^2 = 2 g h = 2 * 32 * 560 b. average speed is half of the initial (zero at the top) ... time = distance / speed

*posted on January 11, 2019* -
## math

t + b = 65 3 t + 2 b = 153 solve the system

*posted on January 11, 2019* -
## Math

subtract the equations (to eliminate y) solve for x , then substitute back to find y

*posted on January 11, 2019* -
## chemistry

your technique should work ... not sure about the last "lowest quotient" step C ... 140.22 * .5139 / 12.011 = 5.999 H ... 140.22 * .0864 / 1.0079 = 12.02 N ... 140.22 * .3997 / 14.007 = 4.001 looks like C.

*posted on January 11, 2019* -
## Physics

impulse is the change in momentum the velocity (parallel to the wall) is constant along its flight path the change in velocity (and momentum) is as you say ... normal to the wall ... the incoming and outgoing speeds are both ... 15 m/s * sin(45º)

*posted on January 11, 2019* -
## Math

amount = 8000 * e^(.05 * t)

*posted on January 11, 2019* -
## Physics

a person should land in the pool (as opposed to passing over it) ... their velocity is such that it allows the fall from 1.2 m before they clear the 3.0 m length find the time to free-fall 1.2 m ... divide the time into 3.0 m to find the max safe velocity

*posted on January 10, 2019* -
## Probability

there are 26 red cards, and two black kings 28 possibilities in a 52 card deck

*posted on January 10, 2019* -
## Math

volume = base area * height

*posted on January 10, 2019* -
## Science

find the time for the stone to reach the ground ... 0 = -4.9 t^2 + 5 t + 50 multiply the time by the balloon's velocity , and add 50 m

*posted on January 10, 2019* -
## algebra

why do you need help ... you got the correct response

*posted on January 9, 2019* -
## algebra

I'm afraid that Henry2 has gone astray y = 2/5 x- 17 7/10 ... y = .4 x - 17.7 y = -5/2 x + 20 ... y = -2.5 x + 20 subtracting equations ... 0 = 2.9 x - 37.7 ... solve for x

*posted on January 9, 2019* -
## Chemistry

the atomic mass of potassium is ≈ 39.1 g find the fraction of a mole in the cereal

*posted on January 8, 2019* -
## algebra

the leading term has the greatest exponent ... 5 in this case ... you should use the "caret" symbol (^) for exponentiation 5 is odd, so the behavior at the positive and negative ends of the graph are opposite a large negative x value causes the function to

*posted on January 8, 2019* -
## Algebra

the (2M+5) takes the place of X in the function f(2M+5) = -3(2M+5) + 1

*posted on January 8, 2019* -
## Maths

4 Cos²B + 2 CosB - 1 = 0 use the quadratic formula to find the values of CosB

*posted on January 8, 2019* -
## Maths

it takes 24 man-days to dig the ditch if it takes 3 days, how many men are digging?

*posted on January 8, 2019* -
## Chemistry

hydrocarbons generally combust to carbon dioxide and water

*posted on January 8, 2019* -
## science

the forces acting on the crate are gravity and buoyancy what's the net result?

*posted on January 8, 2019* -
## math

none the lines are parallel and never intersect

*posted on January 8, 2019* -
## science

same idea as the boy kicking the ball

*posted on January 8, 2019* -
## science

the boy exerts a force on the ball the ball exerts an equal (and opposite) force on the boy

*posted on January 8, 2019* -
## algebra

working in decimals is easier subtract the equations to eliminate y solve for the x value, then substitute back to find y

*posted on January 8, 2019* -
## Chem

which has more eggs...a dozen chicken eggs or a dozen goose eggs?

*posted on January 7, 2019* -
## science

mass = force / acceleration

*posted on January 7, 2019* -
## statistics

use a z-score table to find the lengths represented by bottom 20% and the top 15% of the population the top is ≈ 1.04 s.d. above the mean the bottom is ≈ 0.84 s.d. below the mean

*posted on January 7, 2019* -
## Physics

the "balancing" 3rd force is the force 180º opposite the vector addition of the given forces

*posted on January 7, 2019* -
## Algebra

multiplying by 20 ... 20y = -8x + 5 8x + 20y - 5 = 0

*posted on January 7, 2019* -
## Math

8 = 2^3 (2^3)^x = (2^x)^3 = 10^3

*posted on January 5, 2019* -
## math

A) displacement is the distance (and direction) from the starting point to the finishing point ... it is a vector quantity B) the average speed is the actual distance that he ran, divided by the time it took ... it is a scalar quantity C) the average

*posted on January 2, 2019* -
## Math

A. using a planar section through the Earth from pole to pole ... construct a right triangle using the center of the Earth, the equatorial plane, and the line of 46ºN ... the hypotenuse is the radius of the Earth from the center to 46ºN ... the side

*posted on January 2, 2019* -
## Physics

the water in the flask loses heat to the ice ... (mass of water) * (specific heat of water) * (temperature change) the ice melts , and the resulting water is heated to the final flask temperature ... (mass of ice) * (latent heat of fusion of ice) ... plus

*posted on December 23, 2018* -
## science

there are five "stages" heat ice to 0º melt ice heat water to 100º boil water heat steam you will need the specific heats of ice, water, and steam

*posted on December 22, 2018* -
## Science

yes they are usually called "recessive" genes

*posted on December 21, 2018* -
## Chemistry

look up CALCIUM's electron structure

*posted on December 21, 2018* -
## Calculus

as x becomes very large , the -8 and -6 become inconsequential the function approaches 2

*posted on December 21, 2018* -
## math

the side length of the inner triangle is ... 9 - √3 the ratio of the areas is the square of the ratio of the side lengths

*posted on December 19, 2018* -
## math

"within" is taken to mean "not touching a side" the center of the coin must land inside of a "nested" inner triangle whose edges are parallel to the 9 cm triangle and .5 cm inside the ratio of the areas of the inner and outer triangles is the probability

*posted on December 19, 2018* -
## Physics

which one can't you feel?

*posted on December 17, 2018* -
## Physics

speed = wavelength * frequency

*posted on December 17, 2018* -
## Chemistry

P atoms ... 283.89 * .4364 / (P atomic mass) O works the same way

*posted on December 17, 2018* -
## Physics

total ε is ... 3 * 2.20 v total r is ... 3.27Ω + (3 * 0.0100Ω) find circuit current calculate load potential

*posted on December 13, 2018* -
## Physics

twice the voltage drop means twice the resistance

*posted on December 13, 2018* -
## Earth Science

mass number = protons + neutrons atomic number = protons

*posted on December 13, 2018* -
## science help

correct they are the ones that participate in chemical bonding

*posted on December 13, 2018* -
## science

total points is greater than or equal to 420 ... 82 have already been scored ... p = points still needed p + 82 ≥ 420

*posted on December 13, 2018* -
## Algebra 1

w + w + (2 w + 3) + (2 w + 3) = 48

*posted on December 13, 2018* -
## Algebra

multiply 1st eqn by 7 add to 2nd eqn to eliminate x solve for y , then substitute back to find x

*posted on December 12, 2018* -
## Ap chemistry

0.625 = 10 (1/2)^(t / 3) log(0.625 / 10) = (t / 3) log(1/2) or ... 10 , 5 , 5/2 , 5/4 , 5/8

*posted on December 12, 2018* -
## sport

athletes from almost every country in the world participate there are many different sports (events)

*posted on December 12, 2018* -
## math

what graph?

*posted on December 12, 2018* -
## Math or Algebra

(1.8 * 3.6) x (10E-2 * 10E4) multiply the number part ... sum the powers of 10

*posted on December 12, 2018* -
## Math

x is GREATER than -5 ... to the right of -5 on the number line

*posted on December 12, 2018* -
## Physics

the ambient pressure increases by one atmosphere for every 10 m of depth nitrogen (≈ 80% of the air) goes into solution in the blood at elevated pressures , and acts as an intoxicant ... air mixtures where the nitrogen is replaced by helium and/or argon

*posted on December 12, 2018* -
## chemistry

K.E. = 3/2 k t k = 1.38E-23

*posted on December 12, 2018* -
## Algebra 2

from 1st eqn ... y - 1 = 7x substitute for 7x in the 2nd equation

*posted on December 12, 2018* -
## Science

some of the individuals in the population may have traits that will allow them to cope with the changing climate a population can only change itself over time by producing new individuals with new traits...it's a slow process for trees

*posted on December 11, 2018* -
## Math

looks good

*posted on December 11, 2018* -
## pre-algebra

.24 * w = 3.6

*posted on December 11, 2018* -
## Math

I think you're correct ... I'm pretty sure

*posted on December 11, 2018* -
## Math

100 cm = 1 m ... (100 cm)^3 = (1 m)^3 1000 g = 1 kg

*posted on December 11, 2018* -
## Math

divide the cost by the minutes

*posted on December 11, 2018* -
## Science

P.E. = m g h if h is twice as large , then ...

*posted on December 11, 2018* -
## Science

the point where the diver's center of mass is the highest

*posted on December 11, 2018* -
## Physics

system momentum is conserved they have equal and opposite momenta before the collision

*posted on December 11, 2018* -
## science help

three of the questions are mood/opinion...

*posted on December 10, 2018* -
## physical science

density = mass / volume

*posted on December 10, 2018* -
## Algebra

you sure the 6 is not a G??

*posted on December 10, 2018* -
## Physics

the record has a smaller radius 1/2 * 2 * .17^2 * 50 rpm = 1/2 * ω * [(2 * .17^2) + (1.3 * .16^2)]

*posted on December 10, 2018* -
## math

8 * 30 = (8 + g) * 20

*posted on December 10, 2018* -
## Physics

the center of mass of the stick is at 50 cm , 20 cm from the balance point a. 15 cm * 200 g = 20 cm * m b. the normal force equals the weight of the stick and the 200 g mass ... n = g (m + 200 g)

*posted on December 10, 2018* -
## Math

double ... 2 = [1 + (.07 / 3)]^(3 y) ... ln(2) = 3 y ln[1 + (.07 / 3)] ... solve for y continuously ... 2 = e^(.07 y) ... ln(2) = .07 y

*posted on December 9, 2018* -
## math

0 ≥ 4 x^2 + 8 x - 5 0 ≥ (2 x + 5) (2 x - 1) for their product to be positive (>0), both factors must have the same sign both ≥ 0 ... x ≥ 1/2 both ≤ 0 ... x ≤ -5/2

*posted on December 9, 2018* -
## Physics

the wheel had an initial vertical velocity, and was then accelerated by gravity for 8.5 s final vel y = init vel y + (8.5 s * g) ave vel y = (final y + init y) / 2 ave vel y * 8.5s = height horiz dist = x vel * 8.5 s init K.E. + (m g h) = fin K.E. (init

*posted on December 9, 2018* -
## Physics

(1) + (3) = 14 N @ 270º (2) + (4) = 0 resolve 50 N @ 60º into 0º and 90º components combine with 14 N @ 270º the equilibrium force will have the same magnitude, but opposite direction

*posted on December 8, 2018* -
## Math

start with 2 and work your way up 540 / 2 = 270 270 / 2 = 135 135 / 3 = 45 45 / 3 = 15 15 / 3 = 5 2^2 * 3^3 * 5

*posted on December 8, 2018* -
## Physics

distance = average velocity * time d = [(0.0 m/s + 42 m/s) / 2] * 5.9 s

*posted on December 8, 2018* -
## Chemistry

Mg3N2(s) + 6H2O(l) → 3Mg(OH)2(s) + 2NH3(g) water is the limiting reactant ... 75.0 g / 18.0 g/mole = 4.17 moles expected NH3 ... 4.17 / 3 = 1.39 moles ... molar mass NH3 ... 17.0 g % yield ... 15.0 g / (1.39 mol * 17.0 g/mol)

*posted on December 8, 2018* -
## algebra

parallel means same slope only one fits ... not the one you chose

*posted on December 7, 2018* -
## Physics

6Ω total resistance , so 2A current potential difference = current * resistance

*posted on December 7, 2018*