# Posts by Scott

Total # Posts: 3,376

Physics
the basic range equation is d = v^2 * sin(2?) / g v = launch velocity ? = launch angle g = gravitational acceleration level surface (same height) no air resistance

Physics
the horizontal (x) component of the launch speed is ... 284 m/s * cos(43º) the horizontal component is not affected by gravity ... so just multiply by the flight time

Calculus
looks good

Physics 11
velocity is usually a function of the transmission medium probably doesn't change

Physics
m g h

Physics 11
c is the speed of light (like E = m c^2) 3x10^8 m/s

Physics 11
frequency = speed / wavelength f = c / 3.2 m = 93.7 MHz

Maths
4 consecutive heads, then a tail .52^4 * .48

Physics
the net force will be toward the center of the square, along the diagonal it's symmetric, so you only have to do one corner use the gravitational formula ... the diagonal is direct ... the adjacent corners pull at a 45º angle along the diagonal (vector)

Physics
friction

Physics
time = work / power

Physics
yes ... this is a simple "trick" question

Physics
for objects in free fall ... time up equals time down decelerating on the way up ... accelerating on the way down

Physics
m * g * h / t 150 * 9.8 * 2.5 / 3 = ? Watts

Math
1500 = 300 e^(k * 5) ln(5) = 5 k k = 32.2% / hr y(t) = 300 e^(.322 t)

trig
? is in quad III the tangent of the reference angle is ... 8/15

Chem
Ka = [H+][A-] / [HA] 2.34 / 1.86 = 1.26 M 2 x + (.649 - x) = 1.26 Ka = x^2 / (.649 - x) pKa = -log(Ka)

algebra
(50 * 1.2) + (x * .8) = 1 (50 + x) 60 + .8 x = 50 + x

physics
a = f / m ... d = 1/2 a t^2 the acceleration is inversely proportional to the mass the distance is directly proportional to the acceleration

Math
P(t) = 750g (1/2)^(t/250) log(200/750) = (t/250) log(1/2)

Math
3500000 = 450 * 3^w log(70000/9) = w * log(3)

math
a = .2 (a + b + c) 4a = b + c b = .5 (a + c) ... 2b = a + c ... a = 2b - c ... b + c = 8b - 4c ... 5c = 7b ... 5b + 240 = 7b ... b = 120 c = b + 48 = 168

Physics
9.25 t = 1/2 * 2.75 * t^2 1.375 t^2 - 9.25 t = 0 t (1.375 t - 9.25) = 0 t = 0 ... when the black one passes t = 9.25 / 1.375 ... brown catches up

physics
force is in Newtons (not Joules) the force with which the truck is pulling is accelerating the truck and the trailer...you're on the right track...just use both masses ... f = (truck + trailer) * a the force pulling the trailer is the tension between them ... tension = ...

Geometry
(72 - 2 - 2)^2 + (64 - 2 - 2)^2 = D^2

science
fcc has 4 atoms per unit cell 6.02E23 amu per gram (1.2 * 6.02E23) / (63.5 * 4)

Math
12C5 (5x)^5 (2y)^7 12C5 * 5^5 * 2^7 792 * 3125 * 128 = 316800000

Maths science English hindi s.st computer
four parallel 1? resistors have an effective resistance of 1/4 ?

Math
cos(?) = 9/41 = x/r use Pythagoras to find y ... x^2 + y^2 = r^2 sin(?) = y/r ... remember Q IV tan(?) = y/r

Math
the common difference is -4 an = 1 - 4n

Trigonometry
? is 105º clockwise from the x-axis this gives a 75º reference angle with the negative x-axis the x and y coordinates are both negative x = - cos(75º) y = - sin(75º)

maths
18 cm ? 2b + 16 cm ? 50 cm subtracting 16 ... 2 cm ? 2b ? 34 cm dividing by 2 ... 1 cm ? b ? 17 cm

algebra
yes

Maths
sin(?) = 12/200

Science
add all the numbers in the formula if there is no number, a one is understood

science
(54000 m / 3600 s) / 20 s

math
divide the distance on each leg by the speed to find the time for each leg ave. speed = total distance/total time

Math
wow...missing parentheses sure caused a dustup

Math, probability
a fair cube is expected to come up an equal number of times on each side 6 sides, 60 rolls ... each side is expected 10 times a) 10 ... expected outcome b) 30 ... expected outcome c) 30 ... expected outcome d) 0 ... only 6 sides

Algebra 2
f(x) = (x-2)(x-2i)(x+2i)(x-4+?6)

Algebra
3 x = -146 - 4(x + 2) 7 x = - 154

math help
t = 100 (1 + .10)^8

math
9 / (3/4)

maths
the freight train has a 64 km head start ... 32 kph * 2 h the passenger train closes the distance at 20 kph ... 52 kph - 32 kph 64 / 20 = ?

Physics
1/2 m v^2 = m g h v = ?(2 g h) = ?(2 * 9.8 * .45) m/s

Math
the 5th term is 4 differences from the 1st term

Physics 11
the change in velocity (delta v) is ... 9 m/s 5 m/s in one direction, then 4 m/s in the opposite direction

Physics 11
work against friction is ... 2520 N * 130 m change in gravitational potential is ... m g h = 1200 kg * g * 27 m the sum is the total energy energy divided by time (5 s) is the power

Physics 11
yes

math

Geometry
Pythagoras w^2 + 13^2 = 59^2

Physics 11
the ball is in free fall with no air resistance gravity is the only force on the ball net force is ... m g

MATH
your answer is P(red) the question is P(not red) the two probabilities sum to 1 ... something is either red or not

math
14^2 = 196 31^2 = 961

Algebra 2
2t + 3r + f = 39 t = r + f 3r - 1 = f subs ... t = r + 3r - 1 = 4r - 1 subs ... 8r - 2 + 3r + 3r - 1 = 39 find r, then substitute back

Math
d = original dimension d plus 50% is 1.5 d 1.5 d minus 20% is 1.2 d 1.2^2 = 1.44 final is 44% larger than original

Algebra
yes

physics
drop speed relative to rest ... s = 90 kph / tan(40º) drop speed relative to vehicle ... s = 90 kph / sin(40º)

Math
6C3 combination implies that order is not a factor

math
Q IV ... x is positive, y is negative (b,-a)

physics
work = m g h in real life, terminal velocity becomes a factor

physics
60 mph = 88 ft/s a) the average speed while stopping is 30 mph or 44 ft/s ... the stopping time is ... 200 ft / 44 ft/s divide the initial speed by the stopping time to find the acceleration b) same process as a) but with a different initial speed

Math
D = s + 1 s = b + 3 ... b = s - 3 D + s + b = 31 s + 1 + s + s - 3 = 31 find s, then substitute back

Math
the area is found by multiplying the base by the height

Physics
is the lift moving up or down it makes a difference

maths
sin(?) = 18 / 30

Algebra 2
[(a1 + a23)/2] * 23 = s23 [(10 + a23) / 2] * 23 = 2760

Math
c) the pedal is at 32 cm twice per revolution ... going down and going up 4th time would be 2nd time during 2nd cycle

physics
the change in momentum of the car is equal to the change in momentum of the truck

Math, identities and equalities
expand the cube of the binomial ... the x^3 terms will cancel ... consolidate like terms match the term coefficients with the left hand side solve the resulting equations for a, b, and c

Physics 11
the work calculation is the total work the components are not separable ... not enough information

Mathse
use vector addition on the two components ... a^2 + b^2 = c^2

Physics 11
the friction/work hint is a good one 90 * g * .6 * d = 720

OH for three... no such thing as an equilateral right triangle only one way each to make the other two

Physics
energy = work 2200 J = 1100 N * ? m

Math
looks good

Math
x^3 + 3x^2 + 2x = x^3 + 21 3x^2 + 2x - 21 = 0 (3x - 7)(x + 3) = 0 x + 3 = 0

logs
yes ... that would equal t

physics
the horizontal distance to the edge of the water is ... 10.0 m * tan(40º) the time to fall the 10 m is ... ?(2 * 10 / g) divide distance by time to find the speed

squaring a binomial ... use FOIL (2?5)^2 + 2 * 2?5 * 3?7 + (3?7)^2 20 + 12?35 + 63 = 83 + 12?35

Math
the 3rd side of a triangle must be long enough to connect the ends of the other two sides ... it must also be short enough that the other two sides can connect its ends difference of other two sides < ... 3rd side < sum of other two sides

Physics
a) 20 rad/s * 40 cm/rad b) [a)] * 6 s / 100 cm/m

Physics

Science
ave vel = 10.0 m / 5.0 s = 2.0 m/s final is zero, so initial is ... 4.0 m/s deceleration is ... 4.0 m/s / 5.0 s = 0.80 m / s^2

Math
the exponents form a converging geometric series multiplying (product) numbers with the same base (3 in this case) means adding the exponents 3^(1/3 + 1/9 + 1/27 + ...) there is a formula for the sum of an infinite geometric series ... look it up

algebra
subtracting 4 ... x^2 - x - 6 = 0 factoring ... (x + 2)(x - 3) = 0 individually ... set each factor equal to zero ... solve for x

Algebra
n is the number of the term plug in 1, 2, 3, and 4 for n to find the 1st four terms

Math
5x + 4y = 210 ... 4y = 210 - 5x A = 4 x y = x (210 - 5x) = 210x - 5x^2 max A on axis of symmetry ... x = -210 / (2 * -5) = 21

geometry
(a) if the smaller circle is inside the larger circle , the center-to-center distance is ... 7 cm (b) if the smaller circle is outside the larger circle , the center-to-center distance is ... 19 cm

Science
gps operates by using satellite signals

Physics
a. the acceleration is a function of gravity...it is essentially constant b. see a. gravitational acceleration (g) is 9.8 m/s^2 ... for every second you fall, you go 9.8 m/s faster for c. and d. , multiply the free-fall time by the acceleration (g)

math
9 * 5 = 45 man-days ... like man-hours, only longer 45 man-days / 6 men = ?

physics
V1 = speed at top of window V2 = speed at bottom of window h = height of window T = time of passage [(V1 + V2) / 2] * T = h V2 = V1 + g T [(V1 + V1 + g T) / 2] * T = h V1 T + (g T^2 / 2) = h V1 = (h / T) - (g T / 2)

Algebra2
the common difference is 6 -2 + (49 * 6) your answer looks good

math homework
the speed of the boats is not mentioned...it is a factor

math
h = -1/2 g t^2 + 40 t + .25 h = 0 , g = 9.8 m/s^2 solve for t ... quadratic formula works good ... you want the larger positive value

College Physics
m * g * .15 * 30 = 20000

Physics
forgot a small detail ... v0 is squared ... v0^2

Physics
R = horizontal range (m) v0 = initial velocity (m/s) g = acceleration due to gravity (9.80 m/s2) ? = angle of the initial velocity from the horizontal plane (radians or degrees) R = v0 * sin(2?) / g

Math
six 5's wide , and four 5's long 6 * 4 = ?