Answers by visitors named: R

wavelength = speed / frequency = c / 5.5E14 = 3.0E8 / 5.5E14 meters

6 years ago

looks good

6 years ago

a) the balloon is at the top of the building at time zero ... h = 192 b) the time for max height is at the vertex of the parabola ... on the axis of symmetry ... x = -b / 2a ... t = -64 / (2 * -16) ... plug the value of t into the equation to find max hei...

6 years ago

f = G M m / r^2 if one of the masses is only 80% , then the force (weight) will be 80%

6 years ago

substitute 7x-9 for y ... 6x - 10 (7x - 9) = 730 ... 6x - 70x + 90 = 730 solve for x , then substitute back to find y

6 years ago

1/2 p = -1/16 ... so p = ? vertex is correct

6 years ago

yes

6 years ago

Gm is 1E9 m ... cm is 1E-2 m 4.35E11 cm = 4.35E9 m = 4.35 Gm

6 years ago

the horizontal component of the impact velocity is the thrown velocity the vertical component of the impact velocity is ... √(2 g h) √(2 g h) / (thrown velocity) = tan(45º)

6 years ago

when reflecting over the x-axis ... the x-coordinates stay the same ... the y-coordinates change sign

6 years ago

your choice looks good

6 years ago

wrong end of the visible spectrum

6 years ago

h = 1/2 g t^2 horizontal velocity is not a factor

6 years ago

same answer

6 years ago

the center of mass of the rule is 5 cm from the knife edge (towards B) the 10 g mass is 35 cm from the knife edge (towards A) the rule is balanced , so the moments are equal 5 cm * (mass of rule) = 35 cm * 10 g

6 years ago

f = m a the total mass of the system is Ma plus Mb the total force is gravity on Mb short cut ... B is 1/3 of the total mass , so the acceleration will be 1/3 of g

6 years ago

looks good

6 years ago

a supernova explosion is necessary to produce the heavy elements that are present in the solar system

6 years ago

f = m a ... one of NEWTON'S Laws

6 years ago

the last day is six days from the first day 1st day = f last day = f + 6(20) = f + 120 arithmetic series average = (1st + last) / 2 = (2 f + 120) / 2 = f + 60 for 7 days ... food = 7(f + 60) = 7 f + 420 = 1260 ... 7 f = 840 ... f = ?

6 years ago

g = greater , s = smaller g + s = 54 ... g = 54 - s 4 g = 5 s solve the system ... maybe substitution would be good

6 years ago

a) (velocity change) / acceleration = time ... (3.30 m/s / 12.5 m/s) / (-5.60 m/s^2) = t b) distance = average velocity * time ... d = [(12.5 m/s + 3.30 m/s) / 2] * t

6 years ago

V(x) = x (9 - 2x) (11 - 2x) plug in 1 for x and solve for V

6 years ago

log (common logarithm) means power of ten 8 x^3 = 10^4 (2 x)^3 = 10^4 ... 2 x = ∛10000

6 years ago

the slope of the given line is 2 ... y = m x + b , m is the slope perpendicular lines have negative-reciprocal slopes ... so the new line slope is -1/2 (2 - k) / (4 - -1) = -1/2 ... solve for k

6 years ago

everyone saw the rounding requirement...right? 10.7722

6 years ago

looks good

6 years ago

the potassium-argon dating cycle is more complex than carbon-14 from "hyperphysics" ... t = 1.804E9 ln[9.540(Ar/K) + 1]

6 years ago

x * .30 = 6 kg * .21

6 years ago

the K and Ar atoms in the question are assumed to be the radioactive isotope and its decay product the isotope (K-40) is only .0117% of natural K using total Ar and total K would give an age prior to the "Big Bang"

6 years ago

(j + k)^3 = j^3 + 3 j^2 k + 3 j k^2 + k^3 (3a+4x)^3 = (3a)^3 + 3[(3a)^2 (4x)] + 3 [(3a) (4x)^2] + (4x)^3

6 years ago

heat lost by iron equals heat gained by ice heat = 0.11 * 120 * 90 = ? look up "heat of fusion" for H2O ... divide into ?

6 years ago

L = 2 W L * W = 12 substituting ... 2 W * W = 12 ... W^2 = 6 solve for W , substitute back to find L

6 years ago

3 r^3 = 192 ... r^3 = 64 A = 3 r B = 3 r^2 find r and solve

6 years ago

(s + 4) (s - 2) = 55 ... s^2 - 2s - 63 = 0 solve for s (factoring or quadratic formula) s^2 is the area you seek

6 years ago

h = -1/2 g t^2 + [98.0 sin(87.0º)] the max is on the axis of symmetry ... t = -b / 2a = -[98.0 sin(87.0º)] / -g solve for t ... plug into h equation to find max height

6 years ago

I agree with you ... p ≥ 1 ... the direction changes if you multiply or divide by a negative quantity alt-242 and alt-243 are ≥ and ≤

6 years ago

gravitational force is ... m g 0.50 v^2 = m g = 90 * 9.8

6 years ago

b = h + 5 b + 2 = 2 (h + 5 + 2) solve the system ... substitution seems like a good approach

6 years ago

oops... 2nd equation should be ... b + 2 = 2 (h + 2)

6 years ago

google "north american air masses"

6 years ago

(x + 5)^2 - (3 y)^2 ... factor the difference of squares

6 years ago

work = force * distance

6 years ago

1/2 m v^2 = m g h - friction work 50 v^2 = (100 * 10 * 50) - (100 * 150)

6 years ago

the error could be related to significant figures ... just because the calculator shows them, doesn't mean they are there all of the data in the problem is 2 sig fig ... except for the mass of the ball, which is one sig fig assuming the ball is exactly 10...

6 years ago

quarterly ... {[1 + (0.12 / 4)]^4} - 1 = ? simple ... 0.1355 which is greater

6 years ago

vacuum and radiation spacecraft must be air tight and shielded

6 years ago

whether it is slid up or lifted up , the work is equal to the change in gravitational potential energy ... m g h

6 years ago

if one mole produces seven , how many produce five?

6 years ago

normal force = m g centripetal force = m v^2 / r μ static = centripetal / normal = v^2 / (g r)

6 years ago

google "range equation"

6 years ago

find the net force (up - down) f = m a ... a = f/ m

6 years ago

see "range of a projectile" on wikipedia

6 years ago

PCl5 ⇄ PCl3 + Cl2 0.030 = [PCl3] [Cl2] / [PCl5] = x * x / (0.040 - x) x^2 + 0.030 x - 0.0012 = 0 solve for x

6 years ago

a+2b=13 ... multiplying by 2 ... 2 a + 4 b = 26 2a-3b=5 subtracting equations (to eliminate a) ... 7 b = 21 solve for b , then substitute back to find a

6 years ago

the number of protons is the atomic number of an element ... its number in the periodic table atoms are neutral ... so the number of electrons is the same as protons elements (atoms) have isotopes ... same number of protons , but different number of neutr...

6 years ago

circumference is .... π * diameter one circumference per revolution 12 inches in a foot

6 years ago

you want the LCM of 15, 18, and 25 multiply the prime factors ... 2 * 3 * 3 * 5 * 5

6 years ago

change in y / change in x

6 years ago

rules of exponents inverting the fraction changes the sign of the exponent fractional exponent is a root ...x^1/2 = √x (16/81)^-3/2 = (81/16)^3/2 = (√81 / √16)^3

6 years ago

.74 * 315 = ?

6 years ago

32 is the perimeter the area is the square of the side ... in this case , A^2

6 years ago

each elevation value is 95 more than the previous value ... it is changing 95 per hour y = (hour * 95) + 1123

6 years ago

30 ft is 10 yd 10 yd in 6 min ... 35 / 10 = t / 6

6 years ago

ooops ... 35 / t = 10 / 6 sorry about that ... looks just like Ms. Sue's

6 years ago

h = 1/2 g t^2 = 4.9 t^2 t + (h / 340) = 3.8 ... h = 340 (3.8 - t) = (340 * 3.8) - 340 t substituting ... 4.9 t^2 + 340 t - 1292 = 0 solve for t , substitute back to find h

6 years ago

1/9 = .111111111... this looks like 8/9

6 years ago

twice as many ms , so there were 9 last year that means 9 fewer hs this year

6 years ago

if gets poured ... will have not --- was poured ... has so, before pouring L + M = 35 ... M = 35 - L 4 (L - 7) = M + 7 ... 4 L = M + 35 substituting ... 4 L = 35 - L + 35 ... solve for L

6 years ago

okay ... exact will do for approximate sometimes when something is approximated , you hit it right on the nose

6 years ago

p^2 = (54 - 12)^2 + 34^2

6 years ago

(80 kg + 20 kg) * g * 6 m = work ... in Joules

6 years ago

wavelength =velocity / frequency velocity = c = 3.0E8 m/s

6 years ago

the force in the direction of motion is ... 125 cos(34º) N

6 years ago

they work just like equations BUT ... when multiplying or dividing by a negative quantity , ... the direction of the arrow reverses

6 years ago

A(30) = -1 + (30 - 1) 2

6 years ago

f(7) = (3 * 7) - 5

6 years ago

each term is 10 less than the previous term just follow the pattern

6 years ago

what help ... you chose the correct response

6 years ago

each term is -1 times the number of the term A(n) = -n

6 years ago

each term is 2 more than the previous term the 1st term is -5

6 years ago

sure, post your questions

6 years ago

x (x + 2) = 224 ... x^2 + 2 x - 224 = 0 solve for x

6 years ago

L = 2 W + 2 L * W = 12 substituting ... W (2 W + 2) = 12 ... W^2 + W - 6 = 0 solve for W , then substitute back to find L

6 years ago

160 = 112 t - 16 t^2 solve for t

6 years ago

the gravitational potential becomes kinetic energy 1/2 m v^2 = m g h ... v = √(2 g h)

6 years ago

the center of mass of the rule is at 50 cm using the 70 cm pivot ... (20 * w) + (10 * 0.1) = 15 * 0.4 solve for w

6 years ago

the rule is in equilibrium , so the moments are balanced (equal and opposite) around the pivot point the 20 is the distance from the pivot to the center of mass of the rule

6 years ago

7/5 * 1/4 = ?

6 years ago

f = ml 40% , t = ml 10% f + t = 200 ml .4 f + .1 t = .2 * 200 ml solve the system for f and t

6 years ago

the radius is ...√[(3 - -2)^2 + (1 - 4)^2] the distance to B is ... 8 - 4

6 years ago

there are 10^5 cm in a km one cm on the map represents two km on the ground

6 years ago

multiply by 100 (two decimal places) ... 41.666666... subtract ... 41.66666666666 - 0.41666666666 = 41.25 100 n - n = 99 n = 41.25 ... n = 41.25 / 99 = 4125 / 9900

6 years ago

gosh ... an error in an answer key ... who'd a thunk it you can either believe a nebulous source ... or your own eyes

6 years ago

the frequency is inversely proportional to the period 2.05 * 200 = p * 300

6 years ago

a. 8 rad/s * (1 rev / 2 π rad) * 60 s/min b. 8 rad/s * 20 cm/rad * 10 s

6 years ago

the circumference (distance around the wheel) is ... diameter * π the wheel rolls on the circumference ... so it travels one circumference for each revolution travel = diameter * π * revolutions 12 inches in a foot

6 years ago

what do you get when you divide 5 by 8 with your calculator? we used to have to do it by hand ... long division

6 years ago

P(A) or (B) or (both) = P(A) + P(B) - [P(A) * P(B)]

6 years ago

p v = n r t convert ºC to ºK and make sure your r value has the correct units ... liters, moles, ºK, atm

6 years ago

R_scott

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