# Posts by Justin

Total # Posts: 962

**chemistry**

Are my answers correct? Identify each energy exchange as primarily heat or work and determine weather the sign of ΔE is positive or negative for the system. A. A rolling billiard ball collides with another billiard ball. The first ball (system) stops rolling after the ...

**chemistry**

Are my answers correct? Identify each energy exchange as primarily heat or work and determine weather the sign of ΔE is positive or negative for the system. A. A rolling billiard ball collides with another billiard ball. The first ball (system) stops rolling after the ...

**math**

.An angle is 10° more than the measure of its complement. Find the number of degrees in each angle.The angles measure _ degrees.

**math**

An alloy of copper is 10% copper and weighs 25 pounds. A second alloy is 18% copper. How much (to the nearest tenth lb.) of the second alloy must be added to the first alloy to get a 13% mixture.

**math**

Two angles are complementary. One contains 30° more than the other. Find both angles. The measures of the angles are _ degrees

**math**

If the angle of declination is known, a surveyor would use_______ to find the length x. The cosine of a 50° angle is_______ this represents the value created when length x is divided by 90 feet. If the angle of declination changed to 60°, the cosine would be 0.5; now ...

**math**

The Smiths want to buy a 9 ft. by 12 ft. carpet and center it in a 15 ft. by 20 ft. room. Can a 3 1/2 foot by 12 foot couch be placed against one of the long walls of the room without touching the carpet?

**Chemistry**

please help me balance these equations using the method of half reactions.. Na + HCL = NaCl + H2 Pb + PbO2 + H2SO4 = PbSO4 +H2O Thank you, even a little help is appreciated.

**Biology**

Exogenous treatment with the plant hormone, ABA or auxin, induces enhanced susceptibility against biotrophic pathogens. Design an experiment that can reveal whether these hormones use the same signalling pathway or independent pathways to induce susceptibility.

**English**

In "Paul's Case," members of the faculty don't like Paul's carnation because they think A. it doesn't match his other clothing. B. it suggests that he's not taking things seriously. C. it's the mark of an early death. D. it's effeminate ...

**physics**

A)A model rocket is launched straight upward with an initial speed of 47.7 m/s. It accelerates with a constant upward acceleration of 2.02 m/s2 until its engines stop at an altitude of 157 m. What is the maximum height reached by the rocket? B)How long after lift off does the ...

**economics**

you find out that your aunt works for a defense manufacturing company that has several defense contracts with the government. she tells you that she works for a team that is producing a communications satelluite

**Math**

Thank you

**Math**

Find four ratios equivalent to 30%

**world history**

What was the goal of Americanization programs in settlement houses?

**Lang Arts**

A Retrieved Reformation By: O. Henry

**Lang Arts**

2. What do you learn about Ben price's character from his actions at the end of they story a. He is a determined man who will stop at nothing to catch Jimmy b. He is a forgiving man who is willing to let jimmy go c. He is a jealous man who wants Annabel for himself d. He ...

**math**

find the area under the normal distribution curve to the right of z = -2.40

**math**

find the area under the normal distribution curve between z = -1.25 and z = 2.20

**Stats**

If a student's rank in a class of 300 students is 111, find the student's percentile rank

**Physics**

A 153 g bullet is fired from a rifle having a barrel 0.794 m long. Assuming the origin is placed where the bullet begins to move, the force exerted on the bullet by the expanding gas is F = a + bx − cx^2 , where a = 12600 N, b = 8420 N/m, c = 10100 N/m^2, with x in ...

**Physics**

I figured it out. The answer is 10973.29 J. You just jsd2272 your x values mixed up. Thanks for the equation though. :)

**Physics**

That answer was wrong :(

**Physics**

So f = (9.8)(153) and d=.794? And then do I solve for x? How would I solve for x? ( never taken calculus)

**Physics**

A 153 g bullet is fired from a rifle having a barrel 0 . 794 m long. Assuming the origin is placed where the bullet begins to move, the force exerted on the bullet by the expanding gas is F = a + bx − cx 2 , where a = 12600 N, b = 8420 N / m, c = 10100 N / m 2 , with x ...

**Stats**

According to a Louis Harris poll, 63% of male drivers always use seat belts. A recent sample of 900 male drivers showed that 60% of them always use seat belts. Test at the 0.01 lovel of significance if the proportion of male drivers who always use seat belts is less than .63.

**Phyics**

One of the concrete pillars that supports a house is 1.9 m tall and has a radius of 0.55 m. The density of concrete is about 2.2 x 103 kg/m3. Find the weight of this pillar in pounds (1 N = 0.2248 lb).

**science**

1 what would cause a plant to have a shorter day. 2 what would cause a plant to have a longer day

**math**

-233 + (-233) = 0 ? is this corect? Thank You

**mathematics**

Which number is equivalent to 0.00000001: 10 to the seventh power or 10 to the negative seventh power? How do you know?

**Chemistry**

which is more accurate direct weighting or weighing by difference?

**history**

what is a good website to describe a boom town in the west in the 1800s. a website of what they do there and what occurs during a typical day of mining.. including techniques of mining, description of the town, the mines, and the town's inhabitants... also efforts to ...

**history**

thank you :)

**history**

use ten adjectives to describe ghost towns. I got: 1-abandoned 2-ancient 3-lonely 4-broken down 5-old 6-empty 7-sad 8-quiet I still need 2 more adjectives, but I am all out of ideas.. please help, thank you

**social studies (history)**

yes they do

**social studies (history)**

well clique means a small group of people, with shared interests or other features in common, who spend time together and do not readily allow others to join them.. so wouldn't it be that vigilant justice is similar to cliques in middle school because vigilante justice ...

**Calculus**

Your Porsche's gas mileage (in miles per gallon) is given as a function M(x) of speed x in miles per hour. It is found that M'(x) = 3,600x−2 − 1/ (3,600x−1 + x)2. Estimate M'(10), M'(60), and M'(90). (Round your answers to seven decimal ...

**Calculus**

ok, maybe this is more accurate... M'(x) = (3600x^-2 -1)/ (3600x^-1 +x)^2

**Calculus**

Your Porsche's gas mileage (in miles per gallon) is given as a function M(x) of speed x in miles per hour. It is found that M'(x) = 3,600x−2 − 1/ (3,600x−1 + x)2. Estimate M'(10), M'(60), and M'(90). (Round your answers to seven decimal ...

**physics**

(a) What is the hot resistance of a 24 W light bulb that runs on 120 V AC? (b) If the bulb's operating temperature is 2700°C, what is its resistance at 2570°C?

**physics**

(a) What is the hot resistance of a 24 W light bulb that runs on 120 V AC? (b) If the bulb's operating temperature is 2700°C, what is its resistance at 2570°C?

**physics**

As part of a class project you are given 0.900 g of nichrome and asked to fabricate a wire with uniform cross-section. You use up 95% of the nichrome and make a wire with a resistance of 0.840 Ω. The resistivity of nichrome is 1.00 10-6 Ω · m and its density ...

**physics**

Assuming 95.0% efficiency for the conversion of electrical power by the motor, what current must the 12.0 V batteries of a 740 kg electric car be able to supply: (a) To accelerate from rest to 25.0 m/s in 1.00 min? (b) To climb a 200 m high hill in 2.00 min at a constant 25.0 ...

**physics**

Assuming 95.0% efficiency for the conversion of electrical power by the motor, what current must the 12.0 V batteries of a 740 kg electric car be able to supply: (a) To accelerate from rest to 25.0 m/s in 1.00 min? (b) To climb a 200 m high hill in 2.00 min at a constant 25.0 ...

**physics**

I got the solution: copper=3.9x10^-3 iron=5.0x10^-3 R(1+α∆T)=R(1+α∆T) 0.425(1+0.0039∆T)=0.455(1+0.005∆T) ∆T=-48.6°C T=20°C-48.6°C=-28.6°C

**physics**

A copper wire has a resistance of 0.425 at 20.0°C, and an iron wire has a resistance of 0.455 at the same temperature. At what temperature are their resistances equal?

**physics**

A copper wire has a diameter of 1.532 mm. What magnitude current flows when the drift velocity is 0.500 mm/s?

**physics**

If an electron travels 0.150 m from an electron gun to a TV screen in 19.0 ns, what voltage was used to accelerate it? (Note that the voltage you obtain here is lower than actually used in TVs to avoid the necessity of relativistic corrections.)

**Physics**

If an electron travels 0.150 m from an electron gun to a TV screen in 19.0 ns, what voltage was used to accelerate it? (Note that the voltage you obtain here is lower than actually used in TVs to avoid the necessity of relativistic corrections.)

**History**

can you put in a sentence the words to make an offering Hapi (NIle) Osiris Wheat Growth Man Rejoice This is the only problem I need thanks :)

**Physics**

A, B, D, and F

**physics**

What is the force on the charge located at x = +8.00 cm. q = 1.00 µC and a = 8.00? (The positive direction is to the right.)

**physics**

Bees often work together for the greater good of the hive. Sometimes they can get excess charge on them. Four pairs of bees, which can be represented as identical, conducting spheres, bump into each other in the hive. Rank the bees in the order of the size of the magnitude of ...

**physics**

(a) Two point charges totaling 8.50 µC exert a repulsive force of 0.100 N on one another when separated by 0.839 m. What is the charge on each? smallest charge (µC) largest charge (µC) (b) What is the charge on each if the force is attractive? smallest charge...

**physics**

A 45.0 g ball of copper has a net charge of 1.5 µC. What fraction of the copper's electrons have been removed? (Each copper atom has 29 protons, and copper has an atomic mass of 63.5.)

**physics**

(a) Two point charges totaling 8.50 µC exert a repulsive force of 0.100 N on one another when separated by 0.839 m. What is the charge on each? smallest charge (µC) largest charge (µC) (b) What is the charge on each if the force is attractive? smallest charge...

**physics**

Two point charges exert a 2.50 N force on each other. What will the force become if the distance between them is increased by a factor of 5?

**physics**

What is the repulsive force between two pith balls that are 12.0 cm apart and have equal charges of -39.0 nC?

**physics**

A 45.0 g ball of copper has a net charge of 1.5 µC. What fraction of the copper's electrons have been removed? (Each copper atom has 29 protons, and copper has an atomic mass of 63.5.)

**physics**

How many coulombs of positive charge are there in 8.70 kg of plutonium, given its atomic mass is 244 and that each plutonium atom has 94 protons?

**physics**

How many coulombs of positive charge are there in 8.70 kg of plutonium, given its atomic mass is 244 and that each plutonium atom has 94 protons?

**physics**

A 45.0 g ball of copper has a net charge of 1.5 µC. What fraction of the copper's electrons have been removed? (Each copper atom has 29 protons, and copper has an atomic mass of 63.5.)

**physics**

(2.00X10^20)/(-6.25X10^18)=-32.0

**physics**

If 2.00 multiplied by 1020 electrons move through a pocket calculator during a full day's operation, how many coulombs of charge moved through it?

**Chemistry**

Needed to put to lowest coeffecients in this case c2o4 and co2.

**Chemistry**

can someone balance this redox please. frustrating because i don't know what else im doing wrong. C2O4^2- + MnO2 --> Mn^2+ + CO2 my answer is 2C2O4^2- + MnO2 + 4H3O^+ --> Mn^2+ + 4CO2 + 6H2O im getting mad please help thanks.

**physics**

Four identical metallic spheres with charges of +2.2 µC, +8.2 µC, −4.6 µC, and −9.2 µC are placed on a piece of paper. The paper is lifted on all corners so that the spheres come into contact with each other simultaneously. The paper is then...

**Chemistry**

hi. can you explain to me please why this solution please? THANK YOU

**Chemistry**

Given the reaction: Ni (s) + 4 CO (g) Ni(CO)4 (g) E = –154 kJ, how many kilograms of CO are required for this reaction to release 756 kJ of energy?

**Chemistry**

thanks!!!! it was an exercise from study guide it just gave the answer not the solution. might be correction

**Chemistry**

hi this seems simple but i cant figure it out. If a 0.46 kg hot copper pan lost 9.8x103 J of heat as it cooled down to 54°C, what was its original temperature? I used the 24.44 j/molK for heat capacity, is not this one? found on wikipedia: copper this is how i derive my ...

**Chemistry;HELP**

oops my bad. was gonna post new question, sorry i don't know the answer.

**Chemistry;HELP**

Given the reaction: Ni (s) + 4 CO (g) Ni(CO)4 (g) E = –154 kJ, how many kilograms of CO are required for this reaction to release 756 kJ of energy? please

**physics**

19 cars in a circle at a boom box competition produce a 130 dB sound level at the center of the circle. What is the average sound level(dB) produced there by each, assuming interference effects can be neglected? Please someone help me to solve this problem. Thanks a lot.

**physics**

I found the answer: E=(3.16^-3)[(π*0.0085/2)^2](8*3600)=0.00516 J

**physics**

Elena, thank you for your help, but the answer is not correct.

**physics**

An 8 hour exposure to a sound level of 95.0 dB may cause hearing damage. What energy in joules falls on a 0.850 cm diameter eardrum so exposed? I try to use k = IAT = (1*10^-3)(0.0085^2)(8*3600)=0.00208 but answer is not correct.

**physics**

19 cars in a circle at a boom box competition produce a 130 dB sound level at the center of the circle. What is the average sound level(dB) produced there by each, assuming interference effects can be neglected?

**physics**

The amplitude of a sound wave is measured in terms of its maximum gauge pressure. By what factor does the amplitude of a sound wave increase if the sound level goes up by 38.0 dB?

**physics**

An 8 hour exposure to a sound level of 95.0 dB may cause hearing damage. What energy in joules falls on a 0.850 cm diameter eardrum so exposed?

**physics**

(a) By what factor is one sound more intense than another if the sound has a level 17.0 dB higher than the other? (b) If one sound has a level 32.0 dB less than another, what is the ratio of their intensities?

**physics**

A physicist at a fireworks display times the lag between seeing an explosion and hearing its sound, and finds it to be 0.800 s. (a) How far (m)away is the explosion if air temperature is 22.0°C, neglecting the time taken for light to reach the physicist? (b) How much ...

**physics**

(a) By what factor is one sound more intense than another if the sound has a level 17.0 dB higher than the other? (b) If one sound has a level 32.0 dB less than another, what is the ratio of their intensities?

**physics**

An 8 hour exposure to a sound level of 95.0 dB may cause hearing damage. What energy in joules falls on a 0.850 cm diameter eardrum so exposed?

**physics**

The amplitude of a sound wave is measured in terms of its maximum gauge pressure. By what factor does the amplitude of a sound wave increase if the sound level goes up by 38.0 dB?

**physics**

19 cars in a circle at a boom box competition produce a 130 dB sound level at the center of the circle. What is the average sound level(dB) produced there by each, assuming interference effects can be neglected?

**physics**

A physicist at a fireworks display times the lag between seeing an explosion and hearing its sound, and finds it to be 0.800 s. (a) How far away(m) is the explosion if air temperature is 22.0°C, neglecting the time taken for light to reach the physicist? (b) How much ...

**physics**

An 8 hour exposure to a sound level of 95.0 dB may cause hearing damage. What energy in joules falls on a 0.850 cm diameter eardrum so exposed?

**physics**

The amplitude of a sound wave is measured in terms of its maximum gauge pressure. By what factor does the amplitude of a sound wave increase if the sound level goes up by 38.0 dB?

**physics**

Henry, thank you for your help, but the answer is not correct.

**physics**

19 cars in a circle at a boom box competition produce a 130 dB sound level at the center of the circle. What is the average sound level(dB) produced there by each, assuming interference effects can be neglected?

**physics**

(a) By what factor is one sound more intense than another if the sound has a level 17.0 dB higher than the other? (b) If one sound has a level 32.0 dB less than another, what is the ratio of their intensities?

**physics**

A physicist at a fireworks display times the lag between seeing an explosion and hearing its sound, and finds it to be 0.800 s. (a) How far (m)away is the explosion if air temperature is 22.0°C, neglecting the time taken for light to reach the physicist? (b) How much ...

**physics**

Show that 60.0 L of gasoline originally at 15.0ºC will expand to 61.1 L when it warms to 35.0ºC, how much gasoline has spilled by the time they warm to 35.0ºC ?

**physics**

(a) A solar collector is 12.0% efficient in gathering solar energy and converting it to heat. If the average intensity of sunlight on one day is 700 W/m2, what area(m^2) should your collector have to gather energy at the rate of 150 W? (b) What is the maximum cost ($)of the ...

**physics**

What is the wavelength (m)of an earthquake that shakes you with a frequency of 11.5 Hz and gets to another city 85.0 km away in 12.0 s?

**physics**

How many times a minute does a boat bob up and down on ocean waves that have a wavelength of 43.0 m and a propagation speed of 5.25 m/s?

**physics**

When a pendulum with a period of 2.00000 s is moved to a new location from one where the acceleration of gravity was 9.80 m/s2, its new period becomes 1.99711 s. By how much does the acceleration of gravity differ at its new location? (m/s2)

**physics**

Two parakeets sit on a swing with their combined center of mass 15.0 cm below the pivot. At what frequency do they swing?