Thursday

April 17, 2014

April 17, 2014

Total # Posts: 541

**Chemistry**

What mass of NaOH is required to create 500 mL of a .4 M solution of Sodium Hydroxide(aq)?

**SCIENCE HELP PLEASE**

NO we always see the same side of the moon because its rotational period is the same as its orbital period (about 28 days) if the moon rotated every 24 hrs (like Earth), then you would see different parts of the moon during its orbit

**math**

Three times as many childeren as adults attended a concert on Saturday. An adult ticket is $7 and a child's ticket is $3. The theater collected $6000. How many people bought tickets?

**Math**

the .88 is okay, but the exponent is not actually, there is supposed to be one digit to the left of the decimal point 8.8x10^-3 the exponents are subtracted when dividing (1.23/1.4)x10^(-10 - -8) = .88x10^-2 ___ = 8.8x10^-3

**Physics**

the net acceleration is ___ g sin(16.9º) - (4.1×103 N / 3.5 × 103 kg) divide the speed at the bottom by the acceleration to get the time for the trip the average speed is (0 + 4.2) / 2 speed times time is distance (the length of the driveway)

**physics**

the spring compresses until the spring force equals the applied force 14 N = x * 5.0×10^2 N/m

**physics**

w = 1/2 k x^2 where x is the distance stretched

**physics**

the component of gravitational acceleration parallel to the slope is ___ g sin(30º) the force on the skier is ___ m g sin(30º)

**phyics**

with the plane starting from rest and a uniform acceleration, the average velocity is 20 m/s so the time of acceleration is 184/20 or 9.2 s the acceleration is (40 m/s) / 9.2 s

**physics**

the bank angle provides the necessary centripetal force m * v^2 / r = m * g * sin(θ) * cos(θ) convert v to m/s, then solve for r

**Math**

there are three pairs of matching sides two are L x W ___ 2 * 7 * 3 two are L x H ___ 2 * 7 * 9 two are W x H ___ 2 * 3 * 9 find the areas, add them together multiply by the paper cost

**Physics**

the momentum of the system stays constant ___ 94 * .49 forward throw (94 - .27)x + (.27 * 15) = 94 * .49 backward throw (94 - .27)x - (.27 * 15) = 94 * .49

**college math**

.00001 - .0001 10^-5 - 10^-4 -9x10^-5 ___ -.00009

**ap chemistry**

a Coulomb ≈ 6.24x10^18 electrons find the number of moles in 96.5 kC (by multiplying) this equals the moles of Ag produced mass = moles * molar mass

**physics**

your calculated v will be in m/s the question asks for rpm 60 s in a min and circumference = 2πr (60 v) / (2 π r)

**PHYSICS**

f = m a tension = (3.8 * 2.1) + (3.8 * g)

**Physics**

the work is equal to the change in the (kinetic) energy of the truck w = (1/2 m 25^2) - (1/2 m 13^2) w = 1/2 * 8000 * (25^2 - 13^2)

**math**

(15 + 14 + 13 + 12 + 11 + ...) minus (12 + 11 + 10 + ...)

**physics**

no

**Physics**

t is the time for Tina to catch David 1/2 a t^2 = v t 1.45 t^2 = 24 t 1.45 t^2 - 24 t = 0 t = 24/1.45 distance = 24 * 24/1.45 speed = accel * t = 2.9 * 24/1.45

**physics**

the velocity changes by 9 m/s (27 - 18) this takes approx. 2.6 s (9 / 3.5) the average velocity is 22.5 m/s ___ (27 + 18) / 2 the distance traveled is velocity multiplied by time

**science**

power = work / time p = (1000 * m * g * h) / (30.0 min * 60 s/min) p = (1000 * 196)j / 1800 s (watts)

**science**

p.e. = m * g * h 10.3 kj = 5.20 kg * 9.8 m/s^2 * h 10.3 k / (5.2 * 9.8) = h (in meters)

**Phyics**

the rocket attains a velocity of 75.5 * 1.58 or 119.3 m/s since it started from zero, the average velocity for the 1st part of the flight is 119.3/2 or 59.65 m/s it runs out of fuel at a height of 1.58 * 59.65 or 94.24 m in the 2nd part of the flight, the rocket is decelerated...

**physics**

the velocity in the x-direction is constant the penguin is accelerated in the y-direction by the wind a = f / m = .45 / 5.7 v = a * t the x-velocity and y-velocity add as vectors to give the net velocity (vx)^2 + (vy)^2 = v^2

**physics**

push off from your backpack as hard and fast as you can, towards the shore you and your backpack will gain equal amounts of momentum you will slide to solid ground and your backpack will end up on the opposite shore

**Physics**

the net work done on the car, by the driver, is ZERO the force is applied internally to the moving reference frame of the car this would be like sitting in a wagon and trying to move it by pushing on the inside -- no net work

**Physics**

the work stretching the spring equals the change in the gravitational potential energy 1/2 * k * x^2 = m * g * x 37 x^2 = 3.3 * 980 * x = 3234 x x^2 - (3234/37)x = 0 x = 3234/37

**physics**

gravity provides a downward acceleration of 9.8 m/s^2 so the bungee cord is providing an upward acceleration of 1.4 m/s^2 (9.8 - 8.4) the force is upward with a magnitude of 65 kg * 1.4 m/s^2

**Phyics**

velocity = acceleration * time her acceleration is zero for the rest of the race, so her velocity stays constant

**Biology**

Describe how enzymes affect chemical reactions and explain why this makes enzymes important to living things. I need help this will be on my test I am studying for.

**math**

how many ways can a 3 person subcommittee be selected from a committee of 7 people

**math**

using simple interest on a loan at 8.4% for one year making monthly payments. Find the APR on a $5000 loan.

**Math**

Heather has divided $8000 between two investments, one paying 8% and the other paying 6%. If the return on her investment is $550 how much does she have in the larger investment?

**Math (probability)**

Real Estate ads suggest that 50% of homes for sale have garages, 24% have swimming pools, and 11% have both. If a home for sale has a garage, what's the probability that it has a pool too? Write as a decimal.

**Math**

What is the cubic feet of a concrete slab 20ft x 30ft x 6" thick.

**Math(reiny)**

On the earlier questin would the speed be faster not slower?

**Math**

Over a fixed distance speed r varies inversely as time t. If the speed of a car is 30 mph when the time is 6 seconds what would the speed be of the car if the time was 4 seconds

**physics**

m * g * h 80.4 * g * 2630 * sin(19.4º)

**science**

a substance going into solution has no effect on the weight the weight of the solution is the weight of the solvent plus the weight of the solute

**chemistry**

.1M * (45.5 / 50)

**physics**

the two particles experience the same force (the tension in the string) since A has twice the mass of B, its acceleration will be half of B's so A's final velocity will be half of B's (1/2 * 2kg * v^2) + (1/2 * 1kg * (2v)^2) = 12J 2 v^2 + 4 v^2 = 24 v^2 = 4 ___ v =...

**Algebra 2**

the probability of NOT getting a particular glass on any visit is 4/5 or .8 the probability of NOT getting a particular glass on 15 visits is .8^15 the probability of getting a particular glass in 15 visits is 1 - .8^15 the probability of getting all 5 glasses in 15 visits is ...

**physical science**

the tension in the string provides the force for the centripetal acceleration of the stone f = m * v^2 / r = 1 * 5^2 / .5 the force is in Newtons

**physics**

If a metal wire carries a current of 79 . 0 mA, how long does it take for 7.90 × 10 20 electrons to pass a given cross-sectional area anywhere along the wire? The fundamental charge is 1 . 602 × 10 − 19 C. Answer in units of s

**Chemistry**

n and inQ are doubled EAo and E have no change Q is squared

**math**

How much paper is used for a label on a can of frosting. The height of the jar is 5 inches and the radius is 1.5 inches I did SA=2TTrh+2TTr^2 SA=2TT1.5(5)+2TT1.5^2 SA=15TT + 2TT2.25 SA=15TT=4.5TT SA=19.5TT SA=61.261 SA=61.3in^2 61.3in squared of paper was used for the label Di...

**physics**

Consider a pendulum of length 4.720 m. The acceleration of gravity is 9 . 832 m / s 2 . a) What is its period at the North Pole? Answer in units of s 009 (part 2 of 6) 10.0 points b) What is its frequency? Answer in units of Hz

**Math**

Aubrey spent 2/7 of her money and gave 1/4 of the remaining money to her hungry parents. she had $120 left. How much did she have left?

**Algebra**

I need to factor out the greatest common monomial factor: 1) 20x^2y^2 - 4xy 2) 18s^2t^5 - 2s^3t 3) -2g^4 +14g^2 + 6g

**Algebra**

I need to solve these equations : 1) 5w^2 - 5w = 0 2) 2x^2 + 15x = 0 3) -32y^2 - 24y = 0 4) 6h^2 = 3h 5) -42z = 14z 6) -12p^2 = -30p

**Algebra**

How do I factor out the greatest common monomial factor? 1) 9m^7 - 3m^2 2) 12a^5 + 8a 3) I need to describe and correct the error in facotring out the greatest common monomial factor of 18x^8 - 9x^4 - 6x^3 18x^8 - 9x^4 - 6x^3 = 3x(6x^7 - 3x^3 - 2x^2) is INCORRECT

**geometry**

4. In order to properly design a heating system for a greenhouse, the volume of air in the building needs to be determined. Find the volume of air in the greenhouse below. The length of the building is 40 feet long, the width is 20 feet long, and it is 8 feet from the ground t...

**physics**

A steam engine’s boiler completely converts 151 kg of water to steam. This process in- volves the transfer of 4.8786 J J as heat. If steam escaping through a safety valve does 1.66 × 108 J of work expanding against the outside atmosphere, what is the net change in t...

**physics**

A person takes in a breath of 27C air and holds it until it warms to 36.5C. The air has an initial volume of 0.39 L and a mass of 0.00077 kg. Determine the work done by the air on the lungs if the pressure remains constant at 1 atm. Answer in units of J

**Math/Physics**

What is an expression for the standing wave that is produced by adding the two waves (2.5 cm)sin[(3.0 m-1)x - (27 s-1 )t] and (2.5 cm)sin[(3.0 m-1)x + (27 s-1)t]

**Physics**

Air is vibrating in a tube (closed at both ends) at its fundamental frequency of 160 Hz. If the tube is filled with helium instead, what is its fundamental frequency? Use 1020 m/s for the speed of sound in helium.

**Physics**

If the seventh and fourth standing wave frequencies of a string differ by 144 Hz, what is the fundamental frequency of the string?

**Physics**

Write an expression for the standing wave produced by adding the two waves (2.5 cm)sin[(3.0 m-1)x - (27 s-1 )t] and (2.5 cm)sin[(3.0 m-1)x + (27 s-1)t].

**Physics**

Two identical tuning forks have frequencies of 512 Hz. If one is held by a listener while the other approaches at a speed of 7.2 m/s, what does the listener hear?

**Physics**

the horizontal velocity of the ball is ___ Vh = 176 cos(35º) the vertical velocity of the ball is ___ Vv = 176 sin(35º) it takes the ball 565 / Vh seconds to reach the back wall the time to the peak of the ball's trajectory is ___ Vv / g the difference between th...

**Math**

x / (2x + 10) = 5 / 12 "cross" multiplying ___ 12x = 10x + 50

**Physics**

vacuum doesn't pull, pressure pushes b.

**Physics**

500 N/m^2 b.

**Physics**

2 s up and 2 s down the velocity took 2 s to drop to zero (at the peak of the flight) so it must have started at 20 m/s

**Chemistry**

calculate the pH of a 0.2moldm-3 solution of ammonia at 298K given that Kb for ammonia is 1.8x10-5

**Math**

It is not a school question. It is a real life question. So let's assume the interest averaged 4 % compounded daily over the 27 years.

**Math**

$2700 left in an account paying 4% interest would be worth how much today?

**Economics**

$2700 left in a variable rate interest bearing account in 1986 is worth how much today ?

**Math**

If I left $2700 in a variable rate interest account in 1986, how much is it worth today ?

**physics**

A block starts at rest and slides down a fric- tionless track. The acceleration of gravity is 9.81 m/s2 . It leaves the track horizontally, striking the ground (as shown in the figure above). b b b b b b b b b b b b 502 g h 2.2 m 4.4 m 9.81 m/s2 a) At what height h above the g...

**Physics**

Two banked curves on a highway have the same radius. Curve A is banked at 13 degrees and highway B is banked at 19 degrees. A car can travel around curve A without relying on friction at a speed of 18 m/s. At what speed can this car travel around curve B without relying on fri...

**physics**

A flight attendant pulls her 74.2 N flight bag a distance of 324 m along a level airport floor at a constant velocity. The force she exerts is 37.9 N at an angle of 55.2 above the horizon- tal. a) Find the work she does on the flight bag. Answer in units of J 024 (part 2 ...

**physics**

A 42.1 kg diver steps off a diving board and drops straight down into the water. The water provides an average net force of resistance of 1559 N to the diver’s fall. If the diver comes to rest 4.1 m below the water’s surface, what is the total distance be- tween the ...

**physics**

Calculate the speed of an 7.6×104 kg airliner with a kinetic energy of 1.2 × 109 J. Answer in units of m/s

**Physics**

During a baseball game, a batter hits a pop up to a fielder 65m away. The acceleration of gravity is 9.8m/s^2. If the ball remains in the air for 5.7s, how high does it rise? Answer in units of m.

**physics**

65 = .5 g t^2 130 = 9.8 t^2 the distance is 7.8*t

**physics**

.4 = .5 g t^2 .8 = 9.8 t^2 the x-velocity is 76/t

**physics**

A student moves a box of books down the hall by pulling on a rope attached to the box. The student pulls with a force of 173 N at an angle of 27.5 above the horizontal. The box has a mass of 27 kg, and μk between the box and the floor is 0.2. The acceleration of grav...

**physics**

Consider the 57 N weight held by two cables shown below. The left-hand cable is horizon- tal. 57 N 52 a) What is the tension in the cable slanted at an angle of 52? Answer in units of N

**physics**

A 2.67 kg block starts from rest at the top of a 27.6 incline and accelerates uniformly down the incline, moving 2.89 m in 2.45 s. The acceleration of gravity is 9.81 m/s2 . a) What is the magnitude of the accelera- tion of the block? Answer in units of m/s2

**physics**

A 31 kg box slides down a 33.0 ramp with an acceleration of 1.30 m/s2. The acceleration of gravity is 9.81 m/s2 . Find the coefficient of kinetic friction between the box and the ramp.

**math(please help)**

Al + As + B = 124 Al + B = 102 subtracting equations ___ As = 22 Al + As = 86 subtracting equations ___ Al = 64 subtracting equations ___ B = 38

**Physics**

the vertical component of the brick's velocity is 13.9 * sin(27.6º) 0 = (-.5 g 3^2) + [13.9 * sin(27.6) * 3] + (building height)

**Math**

d/dx [cos(x)]^2 = 2 cos(x) * [-sin(x)]

**Pre- AP Physics**

the gravitational force between two objects is the same for both objects

**Math**

a. w = f * d = 150 * 4 = 600 Nm b. 600 / .5 = 1200 Nm

**physics**

A 1.6 kg otter starts from rest at the top of a muddy incline 95.9 cm long and slides down to the bottom in 0.50 s. What net external force acts on the otter along the incline? Answer in units of N

**physics**

A shopper in a supermarket pushes a loaded 32 kg cart with a horizontal force of 10 N. The acceleration of gravity is 9.81 m/s2 . a) Disregarding friction, how far will the cart move in 3.3 s, starting from rest?

**physics**

A freight train has a mass of 3.1 × 107 kg. If the locomotive can exert a constant pull of 4.9 × 105 N, how long would it take to increase the speed of the train from rest to 71.9 km/h? Disregard friction.

**physics**

f = m * a ___ a = f / m a = .052 N / 474 kg v = a * t ___ t = v / a t = 880 m/s / (.052 N / 474 kg) t will be in sec__convert to days

**physics**

Salmon often jump waterfalls to reach their breeding grounds. Starting 1.77 m from a waterfall 0.253 m in height, at what minimum speed must a salmon jumping at an angle of 44.8 leave the water to continue upstream? The acceleration due to gravity is 9.81 m/s2 . Answer in...

**physics**

A basketball player 1.9 m tall wants to make a basket from a distance of 7.8 m. The hoop is at a height of 3.05 m.If he shoots the ball (from a height of 1.9 m) at a 23.5 angle, at what initial speed must he shoot the basketball so that it goes through the hoop without st...

**math**

if an airplane is traveling at 245 meters per second, how many kilometers per second does it travel?

**Geometry**

interior + exterior = 180º

**7th grade Science help**

1. a 2. b 3. d

**math**

divide 1st (multiply by inverse) (1/3 * 7/5) + (5/14 * 7/5) 7/15 + 1/2 = 14/30 + 15/30

**Pre-Calculus**

f(x) + g(x) = (x^2) + (3x + 9) = x^2 + 3x + 9 = h(x) you can break it into whatever pieces you like h(x) = (x + 5)(x + 3) = x^2 + 8x + 15 f(x) = x^2 + 9 ; g(x) = 8x + 6 h(x) = f(x) + g(x) a. f(x) = 3x - 1 ; g(x) = 3 - 2x __ (3x - 1) + (3 - 2x) = x + 2 = h(x) b. f(x) = 7x - 3 ;...

**physics**

it takes 5 s to stop the car __ 55 / 11 the average speed (Va) is __ (55 + 0) / 2 the stopping distance is __ Va * 5 twice as fast means that the stopping time is doubled, along with the average speed __ this means that the car travels 4 times as far

**math**

(3 1/2) / (2 1/3) (7/2) / (7/3) = 3/2 = 1 1/2

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