# Posts by Simon

Total # Posts: 191

physics
A 500N force is applied to a 25 kg block and accelerates it at 15 m/s^2. What is the force of friction?

science
A reaction took place between a magnesium and florine in a large empty container if attraction and repulsive between these atom are equal at a distance of 0.001*10^-10m, calculate the couloumbic force between two atoms.

Chemistry (Insulated Vessel, temperature and vol.)
Insulated vessel has two compartments separated by a membrane. One side is 1 kg of steam at 400 C and 200 bar. The other side is evacuated. The membrane ruptures filling the entire volume. The final pressure is 100 bar. Determine the final temperature of the steam and the ...

Chemistry (Internal Energy)
5 kg of steam contained within a piston-cylinder assembly undergoes an expansion from state 1, where the specific internal energy U(1) is = 2710 [kJ/kg] to state 2, where U(2) = 2660 [kJ/kg]. During the process, there is heat transfer to the steam with a magnitude of 80 [kJ]. ...

physics
Calculate the power required of a 1190 kg car as it climbs a 11° hill at a steady 103 km h-1. The total friction and air resistance is 700 N. Answer in kW, to the nearest whole number.

physics
A skier travelling at 14 m s-1 reaches the foot of a steady upward 14° incline and glides 21 m along this slope before coming to rest. What was the average coefficient of friction?

physics
Total mechanical energy of a flying rubber ball is 2000 J. It has a velocity of 151 ms-1 and is 3.1 m above the ground. Find the mass of the ball. (2dp)

physics
A boy is sledding down a slope that is inclined at 30.0° with respect to the horizontal. A moderate wind is aiding the motion by providing a steady force of 108 N that is parallel to the motion of the sled. The combined mass of the boy and sled is 53.6 kg, and the ...

science
how many seconds will it take for a saterllite to travel 450 km at rate of 120 m/s?

Chem-E / Chemistry
Calculate the rate of heat required to bring 1.80mol/hr of HBr gas from 37.0 C to 434.0C at atmospheric pressure (Heat capacity of HBr is described by eq.) Cp (kJ/mol * C) = a + bT + cT^2 + dt^3 T is in C and HBr - a = 2.910x10^-2, b= -2.27x10^-7, c= 9.887x10^-9, and d= -4....

Chemstry
Dry air is bubbled through 25 litres of water at a rate of 15 litres (STP)/min. The air leaving the liquid is saturated with water at 25 degrees celcius and 1.5 atm. How long it will take for all of the water to vaporize.

Chemistry
Find the volume, in L, of 100g gas mixture containing 10.0 mol% hydrogen in nitrogen at 30.0C and 5.00 atm. Use the avg molecular wt. what is the molar concentration of hydrogen, in mol/L, in the gas mixture? what is the average mass denisity in g/L

Chemistry
semibatch reaction: C6H6(l) +Cl2(g) ==> C6H5Cl(l) + HCl(g) C6H5(l) + Cl2(g) ==> C6H4Cl2(l) + HCl(g) C6H4Cl2(l) + Cl2(g) ==> C6H3Cl3(l) + HCl(g) \reactor contained 11.0 mole of benzene and a product mixture in which the amt of mono-chlorobenzene was 3x the amt of ...

Chemstry
For the reaction A(g) + B(g) <==> C(g) + D(g) the equilibrium constant K is defined as K = Y(sub y) * Y(sub D) / (Y (sub A) * Y(sub b)) where y is the molar fraction of the gas phase of a species At 620.00 K, the equilibrium constant is 1.100. Suppose the feed to a ...

Chemistry
Distillation Scale up: In an experiment 100 lb-mol of 47 lb-mol % ethanol, 53 lb mol % water sol'n is fed into distillation column and separated into two streams: 100lb-mol 0.470 lb-mol ethanol 0.530 lb-mol water goes to: steam 1: 17 lb-mol 0.890 lb-mol Ethanol 0.110 lb-...

math
ralph would like to make a spinner with three diffrent colored regions so that a person would expect to spin the first color half the time,the second color one-third of the time,and the third color one-fourth of the time.is it possibe to make a spinner?Explain

Life orientation
10-15 lines discuss 5 ways in which the human or environmental problem impacts on the community.

physics
Phy 124 – Chapter 22 Problems 1. Consider the following. A spot on a boat is 2.5 m above the water, and the light strikes the water at a point that is 8.0 m horizontally displaced from the spotlight. The depth of the water is 4.0 m. Determine the distance d, which locates...

equation
the smallest 3 consecutive integers is added to twice the largest , the result so obtained is fifteen less than four times the middle integer. find the integers

math
the distance between 2 station A and B is 230 km .two car start simultaneously from A and B in the opposite directions and the distance between them after 3 houra is 20 km. If the speed of one car is less than that of the other by 10 km per hour, find the speed of each cars. (...

math
a rectangle is 5cm longer than it is wide. the diagonal of the rectangle is 20 cm. determine the dimensions of the rectangle. explain and show your work

Calculus
Greetings, This is a question about selecting courses for my semester. I was planning to take Calculus 3 (Mostly 3-Dimensional topics involving calculus) and a C++ programing course. If you have heard of these courses, can you please tell me your thoughts about me taking these...

Linear Algebra
Let v1= (1,1,2,1) v2= (0,1,3,3) v3= (1,-1,-4,-5) v4= (1,0,-2,-4) a) Let U=span{v1,v2,v3,v4}. Find the dimension of U b) Is span {v1,v2,v3,v4}=R4? c) Find a basis for U Very Much Appreciated!!!

Linear Algebra
A test Question: Find the parametric equations of the line through the origin that is orthogonal to the plane 2x+4y-z=0

Electricity and Magnetism
This was actually a test question: Additional Information: This question is based on the Hall effect in a wire. Question: I want you to build a magnetic feild sensor. You have all the properties of the materials and the dimentions of the sensor. a) derive a formula for a ...

Linear Algebra
Find the basis for the following vector space. Please state the dimension of the vector space. S consists of all x in R3 such that x is orthogonal to n=(2,3,2)

linear math
Let u=(2,0,k,-1) v=(-4,0,-3,2) and w= (0,1,0,0). Each answer must be justified(there is no answer where k=nothing) a) find all values of k, (if any) for which u is orthogonal to v b) Find all values of k (if any) for which the set {u,v,w} is linearly independent. Find all ...

world history
. With respect to human rights issues in Southeast Asia, which statement is most accurate? A. The leaders of the Khmer Rouge fled from Cambodia after 1979. B. Chinese merchants living in Cambodia and elsewhere have carried out vendettas against hill tribes. C. The Khmer Rouge ...

Math
The length and width of a rectangle are (x+4) cm and x cm respectively. Write down expressions for: A. The perimeter of the rectangle B. The length of the side of a square with the same perimeter If the sum of the areas of the square and the rectangle is 94 cm^2 , find x. ...

Biology
Why (in detail please) in the carboxypeptidase mechanism, the weak bonds between an enzyme and a substrate will stretch the peptide bond of the substrate which lowers the bond energy? I just want to know why in detail this happens... Thank you.

maths
no worry found the solution to be 200000((t-7/10)^2+1/100) first by multiplying out as above to get 200000t^2-280000t+100000 then taking out the factor of 200000 to get 200000(t^2-7/5t+1/2) then using the formula x^2+2px=(x+p)^2-p^2 to get 200000((t-7/10)^2-49/100+1/2) ...

maths
(400t-300)(400t-300)+(200t-100)(200t-100) complete the square showing all steps

Social Studies
why greater responsibility is placed on the husband in marriage

Quantum Physics
I don't understand why you've used 4 pi in your answer, i assume your rearranged the uncertainty principle equation for delta Px, but isnt the reduced plancks constant h/ 2pi instead of 4pi ?

discreet math
verify that f(n) = 1 + 2 + 4 + 8+..+ 2^n has order 2^n

LIfe orientation
I think the community will encountor many problems due to substance abuse

Physics 30

Physics 30
It takes a plane flying at 150 km/h 3.0 minutes to circle around a cloud at an altitude of 3000m. What is the diameter of the cloud?

Physics HELP! QUICK!
So does that mean you can just use friction force without resolving it into its components, and so what you use in you equation would be: M V^2/R = M g sin A - M g cosA*mu (This is what you did in the previous example) So did you basically just ignore the vertical component of...

Physics HELP! QUICK!
A banked circular highway curve is designed for traffic moving at 55 km/h. The radius of the curve is 220 m. Traffic is moving along the highway at 38 km/h on a rainy day. What is the minimum coefficient of friction between tires and road that will allow cars to take the turn ...

English
Hey "drwls" can you explain to me how you solved a previous physics question that you answered? It's for the following question below, and it's already posted on here. Unfortunately, it didn't allow me to post the link to it, so you may have to search for...

English lit
Alright thank's!

English lit
Who would have thought...eheh last week I had a literature exam about ''The Necklace''. Thanks for the good, tragic, idea. By curiosity, why would the father kill himself? If other people have more ideas, be free to post. Thanks all.

English lit
Thank's for pointing that out Writeacher. I approve that Ms Sue's classic story is more in the spirit of Christmas, but I'm more in search of a story with a suprising ending. When you read the end, you're like : wow, who would have thought that...

English lit
So, for my english class, I'll have to write a Short story ( Exposition Rising Action Climax Falling action Resolution ) I'd like the story to be around the theme of christmas or horror during x-mas. So I need you guys to help inventing a story with a surprising ending...

Math
Reiny is right.

earth
? = 8 :D

physics
Also how did you just substitute mg in for the Normal Force. Cause when I solved for the normal force from the vertical components I got: FNcos A + mu*FNsin A = mg FN = mg / (cos A + mu*sin A) And I basically just substituted that into: FNsin A - mu*FNcos A = m*v^2/R I solved ...

physics
I know its been a while, but I'm just wondering how drwls solved the question without resolving friction into its x-component because isn't the centripetal acceleration directed horizontally instead of parallel to the incline and wouldn't the friction force be ...

Statistics
0.0213

Biology
thanks !

Biology
prokaryotes are not found in following kingdoms, except: (a) Monera (b) Protoctista (c) Animalia (d) All of these Help please!

Biology
prokaryotes are not found in following kingdoms, except: (a) Monera (b) Protoctista (c) Animalia (d) All of these Help please!

Chemistry
Opps... spelled Chemistry wrong.

Chesitry
Calculate the energy needed to melt 50.0 L of nitrogen (N2).

Algebra
(2*x)(4*y)=192

math
In a test, the average was 74 points/100 points. After the test, three of students relocate. Then the average was 75 points/100. The circumstances of the students were 6:5:3. How many points did the three students have? I know the answere is 45, 75 and 90, but can you write ...

math
In a test, the average was 74 points/100 points. After the test, three of students relocate. Then the average was 75 points/100. The circumstances of the students were 6:5:3. How many points did the three students have? I know the answere is 45, 75 and 90, but can you write ...

algebra
The countries "Drømmeland", "Erkerivalia" and "Fantasia" had a competition. Please tell me how maney gold medals the won each with these sentences. 1. They won 17 medals in all 2 "Erkerivalia" won three times more medals than &...

sicence
If you place a metal ring in a region in which a magnetic field is rapidly alternating, the ring may become hot your touch, why? be as specific as you can

Math
Barter question: name will give for a 1 marble 2 paper clips m 2 marker 1 pencil r 5 notepads 4 markers l 1 pencil 5 paper clips g 3 erasers 5 notepads Question how does a get erasers?

math
Logarithm!!! Select all of the following that are true statements: (a) log(2x) = log(2) + log(x) (b) log(3x) = 3 log(x) (c) log(12y) = 2 log(2) + log(3y) (d) log(5y) = log(20y) – log(4) (e) log(x) = log(5x) – log(5) (f) ln(25) = 2ln(5) (g) ln(1) = log(1) (h) ln(e) = ...

life orientation
Genetically modified foods

Stonehenge
Q: How big is Stonehenge? Q: Are some stones on top of other stone? And how were they stacked? Q: How did the stones get there? Q: Did people ever live there? Q: Are the stones heavy? Q: Where is stonehenge?

Stonehenge
What do people do at Stonehenge?

chemistry
This is super confusing complex brain killing A column packing for chromatography consists of a mixture of two types of particles. Assume that the particles in the batch being sampled are spherical with a radius of 0.5 mm. 36% of the particles appeared to be pink and are known...

statistics
A column packing for chromatography consists of a mixture of two types of particles. Assume that the particles in the batch being sampled are spherical with a radius of 0.5 mm. 36% of the particles appeared to be pink and are known to have a polymeric stationary phase attached...

Math
Prove that cos2x=(1-tan^2x)/(1+tan^2x) I can't find any identities that can help me with this. I'm really confused

math
Haha, I just noticed she asked you to do your own question.

math
The question is incomplete.

math
38.9 + 5.58 + 7 + 15.8 Significant digits will round to the whole number due to the 7.

math156
bobpursley, it's a matter of parenthesis.

math156
x/3 = x + 10/6 x/3 - x = 10/6 x(1/3 - 1) = 10/6 x = (10/6)/(1/3-1)

sensory organs
External

science
Vocal Sounds

Social Studies
Why is the First Amendment to the U.S. Constitution so important to us?

Chemistry
Based on the balanced equation Al2S3 + 6H2O → 2Al(OH)3 + 3H2S calculate the number of excess reagent units remaining when 4 Al2S3 formula units and 30 H2O molecules react? Molar Mass (g/mol) Al2S3 150.16 H2O 18.015 Al(OH)3 75.361 H2S 34.082 Avogadro's No. 6.022×...

physics
solve for H: V=LWH

Deliverable Length: 1000-1200 words You are excited about your new position as compliance officer at ECG because this is your first role as a member of a senior executive team. You have the enviable opportunity to be a critical part of ECG’s growth as the leader who will ...

Marketing class
What is the importance of international trade to a country's economy. Advantages of owning an international business?

Economics
it did not help at all. Thanks though.

Lemon
Lime

math
Given A = {1, 2, 3, 4} B = {2, 5, 10, 17}, a E A and b E B The mapping rule for f maps 1 to 2, 2 to 5, 3 to 10 and 4 to 17 (b) Write the mapping rule in the format of the listing method. Display the mapping using the listing format. (c) Write the mapping rule in the format of ...

math
Given A = {1, 2, 3, 4} B = {2, 5, 10, 17}, a E A and b E B The mapping rule for f maps 1 to 2, 2 to 5, 3 to 10 and 4 to 17. (A) Write the mapping rule in the format of the listing method. Display the mapping using the listing format. (B) Write the mapping rule in the format of...

Algebra
law of indices

Arts/social science
What is the relevance of academic study of the Bible today,especially in African context? Define Ethics and show how it relates to Epistemology. Here are previous answers to these very same questions: http://www.jiskha.com/display.cgi?id=1187166711 http://www.jiskha.com/...

University of Botswana
Define Ethics and show how it relates to Metaphysics and Epistemology. Check these sites. http://en.wikipedia.org/wiki/Ethics http://en.wikipedia.org/wiki/Epistemology http://en.wikipedia.org/wiki/Metaphysics Why are we here on Earth? What is our Purpose? How do we relate to ...

University of Botswana
What is the relevance of the academic study of the Bible today,especially in African context. One of the controversies concerns the actual location of the kingdom of Sheba; some scholars say it was in Ethiopia (Africa) and others claim it was in Yemen (Asia). The location of ...

math
can anyone help please, i need a simple formula for working out taxes.if i had any number i need to know what the base was before 16% tax was added. i know the formula if the tax was 17.5%,what ever the total is if you divide that by 47 then x that by 7 that will give you the ...

maths
can any one tell me a way of working out a percentage from a total for tax purposes. Example; if i have a total of 78 and the tax was 17.5% it would be 78 divide 47 x 7 =11.61 can anyone tell me how to work it out if the tax was 16% thanks "78 divide 47 x 7 =11.61 "...

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