# Posts by ivan

Total # Posts: 143

**Science**

Material point is accomplishing harmonic oscillation. What is the time for its displacement from equilibrium position to half of its amplitude ? The period of oscillation is 24 s, and the initial phase is 0 rad.

**science**

What is the period of mathematical pendulum with a lenght of 39,2 m ?

**trigonometry**

a yardstick, held vertically on a level surface, cast a shadow 1 foot 8 inch long. Find the tangent of the angles that the rays of the sun make with the horizontal

**Science**

SCrew u mom

**Science**

In a heat engine, if 700 J of heat enters the system, and the piston does 400 J of work, what is the final internal (thermal) energy of the system if the initial energy is 1,200 J?

**Chemistry**

Question text Calculate the energy required to melt 21 g of ice at 0 oC. The molar heat of fusion for ice is 6.02 kJ/mol. Answer kJ

**Chemistry**

Hi, we have done an experiment in class where we have an equalibrium between (Co(H2O)6)^+2 + 4Cl^- <-> (CoCl4)^-2 + 6H2O where we added HCl dropwise until a colour change occured which changed the solution into a dark blue as the concentration of the Cholride ions ...

**Chemistry**

pepe is tasked with carefully measuring precisely one mole of aluminum. How should pepe go about completing this assignment?

**Math**

period of a 100 MHz FM radio were is roughly 1 X 10 to the negative 8th s. formulate a problem and solution.

**math**

Michelle has half of her investments in stock paying a 6% dividend and the other half in a stock paying 10% interest. If her total annual interest is $680, how much does she have invested?

**Chemistry - Energy: Phase Changes**

Question text Calculate the energy required to melt 21 g of ice at 0 oC. The molar heat of fusion for ice is 6.02 kJ/mol. Answer kJ

**Mathematics**

The specific heat capacity of silver is 0.24 J/g °C. How many joules of energy are needed to warm 0.500 g of silver from 25.0°C to 27.5°C?

**Math**

6 Rows in all (2 more rows of 5 in each row)

**Math**

What is negative eight classified

**Physics**

According to Newton's 3/2 law, the total entropy change that occurs would be calculated by k*(1/2Ke)mv^2+degrees celcius giving you 1.3999898989898989899898

**Math**

A rectangle field has an area of 300 square meters and a perimeter of 80 meters. What are the length and width of the field? I really need help I don't know the answer.

**math**

Wow so do you seriously not know what the answer is Damon? Or are you just this stupid not to answer someone's question? Seriously . . . just wondering do you not know the answer?

**psychology**

Sorry don't know this answer please try again next time! :) LOL!

**Language Arts**

Not agreeable now! :(

**reading**

That means when his nose grew with lies, he can just cut off his nose to make it short again and put it in the fireplace.

**chem**

Is there any monobasic solid acid with a molar mass of 120?

**calculus**

thx so much

**calculus**

lim(x tends to 3) (square root(x^2+7) -4) divided by (square root(x^2-8) -1) Pls help and list the steps. Thx

**Stats**

for a sample of n=20 how large a Pearson correlation is necessary to be statistically significant for a two tailed test

**Physics**

<=3

**math**

what **1/8 means?.

**MATH**

Fraction form 1/3 if changed Decimal form it is 1/3=0.331/3 if changed to Percent form it is 1/3=331/3% Is this correct? I just want make sure.

**math**

in math problem.how to change simplified fraction form 2/3 to decimal form and percent form

**Math**

63250/1000=63.25km 63.25km/7=9.04km 149*9.04=1346.96km so the answer is 1346.96km.

**geomentry**

Which angle is largest, A, B, or C

**statistics**

Scores on a national writing exam are approximately normally distributed, with a mean of 490 and a standard deviation of 20. Consider random samples of size 25 from the population of test takers. describe the sampling distribution of a sample mean. shape mean= standard ...

**chem**

Which of the following ions contains lone pair of electrons at the central atom? A) SO4 2- B) NO3 - C) IO3 - (Is there any ways without drawing the diagrams and I could still able to figure out the answer???) Thx very much

**Material Behavior**

The energy-separation curve for two atoms, a distance, r, apart is: U(r)=−A/r^m+B/r^n Derive and expression for the stiffness of the bond at the equilibrium spacing, in terms of A, B, m, n, and r0. S=dF/dr at r=r0:

**Material Sciences**

steel core, what is the thermal stress in the aluminum shell when the system is heated from the unstressed state (20∘C) to 180∘C? Consider only deformations in the axial directions. Give your answer in MPa αAl=23.6×10−6K−1 EAl=70GPa α...

**Material Sciences**

The energy-separation curve for two atoms, a distance, r, apart is: U(r)=−A/r^m+B/r^n Derive and expression for the stiffness of the bond at the equilibrium spacing, in terms of A, B, m, n, and r0. S=dF/dr at r=r0:

**exam three americangov section 3**

a b c d d d a b c a

**Physics**

The statically-indeterminate composite beam AB of length 2L is fixed at A (x=0) and is simply supported at B (x=2L). The beam is composed of a core of modulus E0 of constant square cross section of dimensions 2h0×2h0 bonded inside a sleeve of modulus 2E0 and constant ...

**math**

A gumball machine contains orange, yellow and purple gumballs. The probability of getting an orange ball is 3/4 and the probability of getting yellow ball is1/6. What is the probability of getting a purple ball?

**Algebra**

List all asymptotes (both horizontal and vertical) of the rational function: f(x)=(10x−3)/(8−7x)

**Dynamics**

A linear spring of stiffness k is designed to stop the 20-Mg railroad car traveling at 8 km/h within 400mm after impact. Find the smallest value of k that will produce the desired result.

**Physics**

A linear spring of stiffness k is designed to stop the 20-Mg railroad car traveling at 8 km/h within 400mm after impact. Find the smallest value of k that will produce the desired result.

**Dynamics**

The man slides the 100-kg crate across force of 200 N. If the crate was initially at rest, how far will the crate move before its speed is 1 m/s? The coefficient of kinetic friction between the crate and the floor is 0.18. The man is pulling the crate at a 20 degree angle.

**Math**

Thank you Ms. Sue I get the same answer. The problem is that teacher offer this answers: a. 29 cm b. 28 cm c. 27 cm d. 33 cm What did we do wrong?

**Math**

The length of a rectangle is 3 cm less than 4 times its width. The perimeter is 74 cm. Find the length

**Chemistry 2**

ok thank you, exactly what i needed to know .

**Chemistry 2**

For the fist order reaction A <-> B, calculate the t1/2(half life) and k(rate constant) and also fill in the blanks. A-Concetration t-time 20 0 10 ? 5 40 sec 3 ? ? 500 sec t1/2=? k=?

**Chemistry 2**

ok thank you, whats the formula to find the time of the missing blanks in the question?

**Chemistry 2**

Thanks man that makes so much clearer. i posted another question similar to this but its a first order reaction. would that change how you work it or is it done the same?

**Chemistry 2**

For a second order reaction A <--> B, calculate the t1/2 (half life) and the k(constant) and also fill in the blanks. A (concentration) t(time) 20 0 sec 10 ? 5 40 sec 3 ? ? 200 sec t1/2=? k=?

**Chemistry 2**

ok i got that now thank you. how will i find the answer for the blanks in the time? is there a formula for it?

**Chemistry 2**

what do you mean?

**Chemistry 2**

For the fist order reaction A <-> B, calculate the t1/2(half life) and k(rate constant) and also fill in the blanks. A-Concetration t-time 20 0 10 ? 5 40 sec 3 ? ? 500 sec t1/2=? k=?

**Chemistry 2**

Thanks man both answers you have answered for me have checked out to mine that i have got.

**Chemistry 2**

When we mix 25.0 mL, 2.0 M BaCl2 with 25.0 mL, 3.0 M Na2SO4 what is the balanced equation? What is the ionic equation? what is the net ionic equation?

**Chemistry 2**

For the reaction: 2A + 3B <--> 4C Kinetic data are as follows A B time needed 10mL 5mL 720 seconds 20mL 5mL 180 seconds 20mL 10mL 90 seconds 30mL 20mL ?? The rate of the equation is?

**Chemistry 2**

Thanks man i appreciate it

**Chemistry 2**

What is the molarity of 50.0 mL solution of aluminum sulfite that contains 80.0 g of this salt? (Al=27.0, S=32.0,O=16.0)

**Math**

If a varies jointly as b and c, and if a = 100 when b = 5 and c = 25, find a when b = 12 and c = 60

**Math**

Thanks Reiny

**Math**

Solve the equation: |6x - 2| = |3x + 1|

**physics**

Participants in a road race take water from a refreshment station and throw their empty cups away farther down the course. If a runner has a forward speed of 6.20 m/s, how far in advance of a garbage pail should he release his water cup if the vertical distance between the lid...

**Physics**

Mary walks west at 2.0m/s for 15 seconds, then north at 3.0m/s for 2o seconds and then east at 4.0m/s for 0 seconds. What is her displacement answer is (108m(N56 DEgrees E)

**Physics**

At that height, you can evaluate the gradient of the normal(which is actually -2.5). then youu find the angle between the horizon and the normal at that height.Let the force acting from the surface along the normal as F.Decompose the force into F_x(parallel to the horizon) and...

**Science**

Wait... maybe

**Science**

Yes

**math**

NELSON GOT A PACK OF 12 PENCILS. HE TOOK 3 PENCILS TO PUT IN HIS DESK AT SCHOOL AND 2 PENCILS TO PUT IN HIS LOCKER AT SCHOOL. WHAT IS THE FRACTION OF TOTAL PENCILS THAT NELSON TOOK TO SCHOOL?

**math**

On a sunny afternoon. The stratosphere tower casts a shadow that is 140 meters long. At the same a nearby flagpole that is 10 meters tall cast a shadow that is 4 meters long . WrirÃƒ© silve the problem

**Physical Science**

A truck whose bed is 2.5m long, 1.5m wide, and 1m high is delivering sand to a construction site. How many trips must the truck make to deliver 7? cubic meters of sand? Plese explain your answer.

**Physical Science**

A truck whose bed is 2.5m long, 1.5m wide, and 1m high is delivering sand to a construction site. How many trips must the truck make to deliver 7? cubic meters of sand? Plese explain your answer.

**Statistics**

0.075

**College Physics**

This answers is wrong don't use please.

**Biology**

b.)

**physics**

A small cork with an excess charge of +7.0 µC is placed 0.16 m from another cork, which carries a charge of −3.2 µC. What is the magnitude of the electric force between the corks? The Coulomb constant is 8.98755 × 10 9 N · m2 /C 2 . Answer in ...

**physics**

Calculate the net charge on a substance consisting of a combination of 8.9 × 10 13 protons and 4.4 × 10 13 electrons. Answer in units of C

**physics**

A negatively charged balloon has 4.5 µC of charge. How many excess electrons are on this balloon? Answer in units of electrons

**physics**

An unclothed student is in 24 ◦ C room. If the skin temperature of the student is 37 ◦ C, how much heat is lost from his body in 6 min, assuming that the emissivity of the skin is 0.83 and the surface area of the student is 1.5 m2 . The Stephan-Boltzmann constant ...

**Physics**

During a certain thermodynamic process a sample of gas expands and cools, reducing its internal energy by 3690 J, while no heat is added or taken away. How much work is done during this process?

**English**

I need help on; how to contrast Walt Whitman perspective of America with the perspective that the members of Occupy Wall Street and the the Tea Party movement have about America.?

**Pre-calculus**

2^(x)/(1-2^(x))=3

**Algebra**

Section Solvers Lessons Answers Click here to see ALL problems on Quadratic-relations-and-conic-sections Question 812207: A gardener is putting a wire fence along the edge of his garden to keep animals from eating his plants. If he has 20 meters of fence what is the largest ...

**physical science**

absolute zero is the same as

**chemistry**

hey! help me

**chemistry**

in saturated sugar solutions what is the solute? what is the solvent?

**Physics**

Vi=60m/s

**phy**

A 3.50 kg block on a smooth tabletop is attached by a string to a hanging block of mass 2.80 kg. The blocks are released from rest and allowed to move freely. 1-Is the tension in the string greater than, less than, or equal to the weight of the hanging mass? 2-Find the ...

**phy**

correction i- 92 mi/h ii- 0/15 m iii- 803 N

**phy**

A major-league catcher gloves a 92 {\rm mi}/{\rm h} pitch and brings it to rest in 0.15 {\rm m}. 1-If the force exerted by the catcher is 803 {\rm N}, what is the mass of the ball?

**chemistry**

1-why should the maximum percent yield never be above 100%?

**history**

2. Why did European economic practices and financial institutions (trading companies, banks, investments, creation of global markets) weaken Middle Eastern and Asian economies and upset local politics? 3. How did countries or empires in the Middle East and Asia attempt to ...

**history**

How did European explorations and commercial activities in the early modern period affect regions of the Middle East and Asia?

**math**

10 degrees of circle in fraction

**nalya sec sch**

do people accomplish more to do things in thiere own way

**Geometry**

How large is an angle whose supplement is three times its complement?

**Geometry**

If we want to find the height of an object like a flagpole, what type of triangle do I use?

**Geometry**

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.

**Geometry**

Find the area of the bedroom in square feet of 11' x 13' 10"

**Geometry**

If a rectangular lot measures 120 ft. x 80 ft., and 10 foot set backs are required from each lot line, how much area is left? If a kennel for 50 dogs requires 12,500 square feet, how many dogs can be accommodated in the small rectangle?

**Geometry**

Mr. Thompson has been asked to add storage space to a garage. He estimates 6 square feet per individual will be required to meet the needs of 12 people. If the storage space is 15% of the total amount of space required, how much total space does Mr. Thompson have?

**Geometry**

Two angles are complementary. One contains 20° more than the other. Find both angles.

**Geometry**

If the boy is 4' 9" tall and his shadow is 6 ft. and the shadow of the flagpole is 19 ft., determine the height of the flagpole (to the nearest tenth).