Tuesday
February 21, 2017

Posts by Scott

Total # Posts: 1,812

pre calc
100% - 30% = (1/2)^(2 / h) log(.7) = (2 / h) log(1/2) h = 2 log(1/2) / log(.7) (after a week) = (1/2)^(7 / h)
November 22, 2016

Algebra
it stops at the top, so the average velocity is ... (103 + 0) / 2 gravitational acceleration is 32 ft/s^2 , downward so the time to reach the peak is ... 103 ft/s / 32 ft/s^2 r * t = d
November 22, 2016

Physics
momentum is conserved, so the truck's loss is the car's gain 7500 kg-m/s / 750 kg = ?
November 22, 2016

physics
radio waves travel at the speed of light (c) ... 3E8 m/s the distance from Venus to Earth depends on where each planet is in its orbit around the Sun
November 22, 2016

technical drawing
85 m is 85000 mm 85000 mm / 10000 = ?
November 22, 2016

science
x + y = 10 3.1 x + 2.5 y = 25 solves easily by inspection (observation)
November 21, 2016

physics
6000 Nm/s = 6 kw
November 21, 2016

Physics
the object displaces 1/5 of its weight in water, so it is 5 times the density of water the weight change in the other liquid is 2/3 of the change in water, so the other liquid is 2/3 the density of water
November 21, 2016

Chemistry
the Ar will effectively be "squeezed" into 80% of its previous volume this will increase the tank pressure to 125% of the original the pp of Ar is 80% of the total the pp of nitrogen is 20%
November 20, 2016

Physics
F accelerates the three boxes equally since C is half of the total system mass, F equals twice the force on C
November 20, 2016

physics
the initial vertical velocity is ... 50 m/s * sin(37º) the (vertical) freefall equation is . h = 1/2 g t^2 + [50 sin(37º)] t + 55 plug in zero for h (ball on ground) and solve for t (use quadratic formula) the horizontal velocity is ... 50 m/s * cos(37º) ... ...
November 20, 2016

math
the intercepts are points with x and y coordinates for x-intercepts, the y coordinates are zero...but they still exist
November 20, 2016

Physics
avg vel = (14 + 0) / 2 = 7 rev/s stop time = 1/7 s distance = 1/2 a t^2 ... 1 = 1/2 * a * (1/7)^2
November 20, 2016

Maths
6 pts total per event 24 pts total awarded...so 4 events Betty has three 1st's and a 2nd Cathy has a 2nd and three 3rd's
November 20, 2016

physics
momentum (as usual) is conserved .05 * v = (5 + .05) * 10
November 17, 2016

applied physics
g = -980 cm/s^2 the object reaches its peak at 2 s average velocity is 980 cm/s ... so peak height is 1960 cm time up equals time down
November 16, 2016

Physics
KE = 1/2 m vB^2 6 KE = 1/2 * m/2 * vA^2 12 = (vA / vB)^2
November 16, 2016

Physics
twice the force, twice the stretch
November 16, 2016

Math
what design?
November 16, 2016

Algebra
the general equation is ... x = a(y - k)^2 + h the vertex is at the origin, so h and k are both zero a = 1 / 4p ... where p is the distance from the vertex to the focus b) the center depth is the value of x at the edges of the dish (where y equals ±7)
November 16, 2016

Physics
the acceleration (j) of the jet and gravitational acceleration (g) are two sides of the triangle j / g = tan(25º) ... j = 9.8 m/s^2 * tan(25º) multiplying j by 11 s will give the takeoff speed
November 16, 2016

Psychics
d = 1/2 a t^2 88.3 = 1/2 * 23.6 * t^2
November 16, 2016

Math
your "weird" answer is correct
November 15, 2016

Math
An = [10 * 3^(n-1)] + 1
November 15, 2016

Technology
the moments about the fulcrum must be equal for balance moment = mass * distance from fulcrum
November 15, 2016

university physics
momentum is conserved with the pellet/block find the velocity of the pellet/block the KE of the p/b is the work that compresses the spring 1/2 m v^2 = 1/2 k x^2
November 15, 2016

Differential calculus
the general vertex form is ... y = a(x - h)^2 + k ... (h,k) is the vertex a = 1 / 4p ... p is the distance from the directrix to the vertex
November 14, 2016

Trig
use Pythagoras (a^2 + b^2 = c^2) to find the angle functions then use the trig identity to find the tangent
November 14, 2016

Advanced physics
the period of the swing (pendulum) is related to its length the speed is not a factor
November 13, 2016

Algebra
a = 2 b 3(a + b) = 90
November 13, 2016

Chemistry
an interesting question will probably make for a lively class discussion a couple of pertinent facts ... normal exhaled air is about 15% O2 ... humans can "survive" in air down to about 6% O2
November 13, 2016

Physics
the work (energy) is equal to the KE of the object f d = 1/2 m v^2 123 * 45.6 = 1/2 * 10.0 * v^2
November 13, 2016

Maths
12 ... 4/10
November 13, 2016

Math (Derivative)
a) y = 6 x^-1 ... dy/dt = -6 x^-2 dx/dt ... dy/dt = (-6 / 64) * 12 b) missing y a typo?
November 13, 2016

Math
p(p + 1) = 3192 p^2 + p - 3192 = 0
November 13, 2016

Science
yes certainly if 180º apart
November 12, 2016

Physics
work (energy) to stop the wagon ... w = 42 * g * .18 * 16 w equals the initial KE of the wagon ... 1/2 * 42 * v^2 = w the speed of the boy is the same as the initial speed of the wagon
November 12, 2016

Chemistry
you are correct
November 12, 2016

Maths
eight "3" cards gives 24 ... 7 shy of 31 replace four "3" cards with three "5" cards and a "4" card
November 11, 2016

Physics
d = 1/2 a t^2 t = ?(2 * d * a)
November 11, 2016

Physics
the period (of the pendulum) is dependent on the length the speed of the "bob" is not a factor
November 11, 2016

math- Trigonometry
looks good...TALL lighthouse
November 11, 2016

Chemistry
.325 L * .05 M/L * 55.8 g/M
November 11, 2016

Math
time is inversely proportional to the number of machines and directly proportional to the number of raviolis t = 15 min * 15/75 * 6000/500
November 11, 2016

science
would call this a "trick" question circular path means radial (centripetal) acceleration there is no tangential component
November 11, 2016

Math
d = 6 233 - 53 = 180 ... so, 31 terms s = (233 + 53) * 31 / 2
November 10, 2016

Physics
1 kcal = 4184 joules m g h = 300 * 4184 h = (300 * 4184) / (1000 * g)
November 10, 2016

Physics
the gravitational potential energy becomes kinetic energy m g h = 1/2 m v^2 v = ?(2 g h)
November 10, 2016

Physics
20º is 1/18 of a circle (20/360) the length of the arc is ... 1/18 * 2 * ? * 1 m
November 10, 2016

Physics
momentum is conserved the smaller mass is 1/3 of the larger ... so it must have 3 times the speed
November 10, 2016

Math
check the related questions
November 10, 2016

Physics
f = m a ... a = f / m a = (33 - 12) / (6 + 15)
November 10, 2016

physics
time up equals time down h = 1/2 g t^2 = 1/2 * 32 ft/s^2v * (2 s)^2
November 10, 2016

math
the x-coordinate doesn't change the sign of the y-coordinate is reversed drawing a picture can help
November 9, 2016

Math
complex roots (zeros with i) occur in conjugate pairs f(x) = (x-6+3i)(x-6-3i)(x^5)
November 9, 2016

math
i = 7400 * [1 - (1 + .06/4)^(4*4)]
November 9, 2016

algebra
try again on the 1st one the slope formula does work
November 9, 2016

physics
the frictional force is ... 5 * 9.8 * .4
November 9, 2016

Physics: Centre of Mass
(4 * 4) + (8 * 5) > 7 * 5 ... so the CM is > 0 [4*(4-x)]+[5*(8-x)]-[7*(5+x)] = 0
November 8, 2016

Math
Tom has a 40 km head start ... 80 km/h * .5 h Cindy is catching up at 20 km/h ... 100 km/h - 80 km/h
November 8, 2016

Physics
the velocity is the vector sum of the horizontal and vertical components horizontal ... 88 m / 3.8 s vertical ... time up equals time down ... (3.8 s / 2) * 9.8 m/s^2 the max height is half the initial vertical component, multiplied by half the flight time
November 8, 2016

Math
distributing the 10 ... 40x + 30 - 9x
November 8, 2016

Math
undefined slope means the line is vertical the equation is of the form ... x = ?
November 7, 2016

Physics
a = v^2 / r r = v^2 / a = (54 m/s)^2 / 90 m/s^2
November 7, 2016

Physics
the object is moving at 20 m/s when the force is removed, the object will be decelerated to a stop (over some distance) by friction find the frictional force (m * g * .2) find the deceleration ... a = f / m find the stopping time ... t = v / a = 20 / a find the stopping ...
November 7, 2016

pre-calc.
100 = 10^2 10 = 10^1 logarithms are exponents -- powers of some base regardless of the base, the logarithm of 100 will always be twice the logarithm of 10
November 7, 2016

Pre-Calc
the values for sine and cosine are limited to the range ±1
November 7, 2016

physics
h = 1/2 g t^2 40 = 1/2 * 9.8 * t^2
November 6, 2016

Physics
gravity follows an inverse square relation two radii above the surface is three times the distance from the center (of mass) to the surface so the force would be ... g / (3^2)
November 6, 2016

physics
Pi * Vi / Ti = Pf * Vf / Tf the T is absolute (Kelvin) temperature
November 6, 2016

physics
you're adding two vectors 2^2 + 4^2 = s^2
November 6, 2016

Physics
need the drawing for a solution or, at least, more data
November 4, 2016

Physics
(b) f = m a ... a = f / m = 900 / 1800 a = .5 m/s^2 so it takes 40 s to stop ... 20 / .5 ave velocity is ... (20 + 0) / 2 distance = v * t
November 4, 2016

Algebra
.12 x + .10(7500 - x) = 890 .02x + 750 = 890
November 3, 2016

Science Psysics
the gravitational potential energy at the top of the ramp becomes kinetic energy at the bottom of the ramp (minus the work done by friction) m g h - f d = 1/2 m v^2 [6 * 9.8 * 3.5 sin(31º)] - (17 * 35.) = 1/2 * 6 * v^2
November 2, 2016

Algebra 2
x^2 - 8x + 14 = 0 use the quadratic formula to find x x = {8±?[64-(4 * 1 * -14)]} / (2 * 1)
November 2, 2016

Algebra 2
use the quadratic formula to find the value(s) of x
November 2, 2016

physics
momentum is conserved (1200 * 14) + (2000 * 25) = ... (1200 + 2000) * v
November 2, 2016

Chemistry
8 half-lives 625 * (1/2)^8
November 2, 2016

Chemistry
3 half-lives m * (1/2)^3 = 6
November 2, 2016

Chemistry
2 days (48 hr) is 8 half-lives 10.0 * (1/2)^8
November 2, 2016

Chemistry
5 / 20 = 1/4 = (1/2)^2 2 half-lives
November 2, 2016

Algebra 2
3 half-lives 345 * 1/2 * 1/2 * 1/2
November 2, 2016

Need help with math
people who own both (b) will be counted in both groups (laptop owners and desktop owners) when you count all of the households, the "both" group is only counted once 130 + 30 + 50 + b = 250
November 1, 2016

Mathematics
the area is side times altitude 30 * 15 = 25 * x
November 1, 2016

Math
8 oz per cup
October 31, 2016

Science
switching the electrical polarity also switches the magnetic polarity
October 31, 2016

Science 7
switching the wires changes the magnetic polarity of the coil
October 31, 2016

algebra 2
3000 = 2000 [1 + (.038 / 2)]^(2t) ... t is the number of years 1.5 = 1.019^(2t) log(1.5) = 2t * log(1.019)
October 31, 2016

Physics
the gravitational potential energy becomes work driving the pipe m g h = f d 450 * g * 1.5 = f * .45
October 30, 2016

Math
y^2 + 5y - 6 = y^2 - 5y + 6 + 8 5y + 5y = 6 + 8 + 6
October 30, 2016

Math
(x + 2)^2 - x^2 = 44 x^2 + 4x + 4 - x^2 = 44 4x + 4 = 44
October 30, 2016

Math
28x - 7y = -119 ... add to 1st eqn
October 30, 2016

math
draw a Venn diagram of three intersecting circles enclosed in a box label the circles S, F, and G S/F/G -- 2 ... these are in all the two way intersections S/F -- 10 + (2) S/G -- 4 + (2) F/G -- 6 + (2) S -- 19 + (2) + (10) + (4) F -- 13 + (2) + (10) + (6) G -- 10 + (2) + (4...
October 30, 2016

Math
A = 3M A - 3 = 4 (M - 3) = 4M - 12 3M = 4M - 9
October 30, 2016

Math
18 r^5 = 2/27 9 r^5 = 1/27 r^5 = 3^-3 / 3^2 = 3^-5
October 30, 2016

Math Grade 9
square rooting implies that the yard is square ... from the result of your answer, this is not the case the "perimeter" in this problem, is only three sides A = L * W = 50 P = L + 2W a good investigation might consist of a table comparing L, W, and P ... remember, ...
October 30, 2016

Algebra
p + r = 18 35p + 49r = 728 solve the system by substitution or elimination
October 30, 2016

math
10 is a factor ... ?????0 The hundred thousands and ten thousands digit are the same and are odd ... must be less than 3, and odd ... 11???0 The sum of the hundreds and the thousands digits is 10 ... neither one can be zero The tens digit is a cube number and is one more than ...
October 29, 2016

Physics
the blocks accelerate at ... 60/18 = 10/3 m/s^2 the force necessary for b ... 15 * 10/3
October 27, 2016

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