Homework Help

Hello everybody, Today is my first day on science forum. I am studying in 9th std. I came upon the following question in my text book, which I was unable to answer. So I am posting this on the scince forum, seeking your help. The question is- "During which situation may an object dropped from a certain height not fall to the earth?" Thanks and regards.

Hi Folks, I am having a devil of a time understand the concept of input work vs input force (relating to machines). OK -- I get that you push down a car's pedal and the car moves. Your force is vastly increased by the car's engine. The input force is much much less than the output force. The car has a mechanical advantage of some factor. But I don't understand how this isn't the same terminology as work. If my input work is pushing the pedal, the car still moves the same amount. The amount of work done by the car is a huge amount more than mine. Sure, my work is the same, but the ouput work is much more than the input work. What am I missing her…

Hi, given that Cs+ has 55 protons and electronic configuration of 2.8.18.18.8, and Cl- has 17 protons and electronic configuration of 2.8.8, why is the ionic radii of Cl- (0.181nm) > ionic radii of Cs+ (0.167nm)? I know that Cs+ has many more protons than Cl-, which means that the pulling force on the electrons in Cs+ is much greater than that on those in Cl-, but what about Cs+ having many more layers of electrons than Cl-? Which has more significance in determining ionic radii, the pulling force on electrons, or the number of layers of electrons? Is there a 'sure' way to determine whether Cs+ or Cl- (or any two ions in different groups and periods, for the ma…

I've got a chemistry exam coming up and am struggling to understand balancing the chemical equation for a redox reaction. Just getting started with breaking it down to 2 half equations is what im stuck on. If anyone has any simple ways it would be much appriciated Thanks

in H2AsO4-. I figured it was four, but I am mistaken. Any pointers?

Hi, I'm doing some biology homework on genetic variation, and I'm kinda stuck! Well so the case is this: Maize plants that were grown from purple grains had cobs that had all purple grains. When fully grown, the resultant plants were self pollinated, giving these results in the cobs produced: Purple grains: 1836 Red grains 578 White grains 772 I have been given a hint that the alleles are: R - red, r - colourless, E - purple, e - colourless, and am supposed to draw a genetic diagram to show the cross described... From the ratio of purple:red:white grains, I'm pretty sure it is recessive epistasis, yet i'm not sure of the relationship between the all…

Hey I am really struggling with this sort of question. I have changed it because I want to do my homework one myself. How would I do this, I know I have to make 5 states and then work out where the numbers go but I have idea. Has anyone got any idea's or tips? The State Transition Table and Output Table for a Finite-State Transducer, with start state S0, are as follows:- State S0 S1 S2 S3 S4 Inputs 1 S4 S3 S4 S1 S1 ...........0 S3 S2 S2 S2 S3 S0 S1 S2 S3 S4 Inputs 1 1 0 0 0 0 ...........0 0 1…

If the mean mercury concentration in fish caught in a particular lake is below 0.5ppm then the state of florida would class that lake as acceptable. On the basis of the data provided in the case study how should the state classify each lake ? so there are basically two lakes, East Lake and Lake Iamonia. East lake mean= 1.1765 sd=0.2802 Lake Iamonia mean= 0.598 sd= 0.2836 formula used = t= mean-value(0.5)/s/square root of n The t-value for the first lake is 15.27, and the total population is 40(fishes) so the answer given by my teacher is t39(0.025) = 3.307< 15.27. So hes looked at the 99.9 % column in the t-table. For the next lake, hes looked at …

Hi everyone. I'm new here. I need a Borosilicate measuring glass for a project but don't know where to get one. Can I get one from a store or do I have to buy online?

This is basically what I am given. I need to use all those variables as a function of the minimum height: I need to figure out what the minimum height of the bridge should be for the person to just barely touch the water, taking into account gravity, the mass of the person, etc. (all listed in the image). I need to take into account the Law of Conservation of Energy (LCE). This is what I came up with, but I'm not sure if it's right: h = (mv²+kx² / 2mg) + (l+L) *the lower case L (l) is supposed to be handwritten, like it appears in the image. Thanks for any help! Edit: btw, this is how I got the equation: mgh = mv²/2 + kx²/2 (by LCE) but h should actually…

Hi, I have a question about normal distribution. A large population of animals were found to possess a mean length of 18cm with a standard deviation of 2cm. What percentage of animals are longer than 20cm? so i know you use the formula to standardize the Z. But then from the cumulative table, how do we know which column to look for? and then the next question is, What percentage of animals should be between 15cm and 20.5 cm in length? in the formula, how do you put both figures 15 and 20.5 ? and then the last question is What length should enclose the shortest 60% of the animals ? please help Also does anyone know a good website for statistics ?

A free game that's worth a look for anyone struggling to learn the periodic table: http://www32.jumbofiles.com:443/d/b5s47r64cr4eam62cx4v66t547rwhkwkslsupcu6rinlun7jcdxmy/Dr%20Who%20Periodic%20Challenge.swf

Hi, I need help with my ANOVA question. There are some things which I am having trouble understanding. Sorry this is going to be long but i need to include details so that it is understandable, i'll try to keep it short though. Below is the data I am working on. Aspirin 5.1 3.8 4.9 2.7 4.7 5.3 3.8 4.0 Paracetamol 4.3 3.8 3.7 4.8 3.5 4.1 3.4 4.0 Ibuprophen 4.2 4.1 4.9 2.9 3.2 5.2 3.0 2.7 Placebo 5.6 5.2 5.3 4.2 5.5 6.0 6.3 5.6 So far, I have calculated the treatment totals (tj) calculated crude sums & sums of squares: SUMx 34.3+31.6+30.2+43.7= 139.8 SUMx^2 5.1^2+3.8^2 etc = 640.52 SUMTj^2 34.3^2…

This is a really weird question...in my opinion... We are told to bake a cake, and we have to use a sulfur solution (sulfur + water ONLY). We must add 100g / L of the solution. (Yes, it's grams, not ml.) How much of the solution should we add to get that amount? From what I know, concentration = mol / L. We know concentration, and we have to find the volume. What I'm not sure is how to calculate for the mol (we're not given a mass) and how to convert the g to ml? I'm not sure if mass is necessary. Or, if we need one, we use a number found in society and indicate why we use it? I'm not sure if I even approached this question correctly...if anyone could help…

Hi , Can anyone help me with drawing a scale plan ? I basically have a free hand sketch of a room, (crime scene) and measured dimensions in cm on it. It contains a window, cupboard, walls, and a piece of evidence in middle of the room with measurements, the position of the evidence is shown by measuring two points from a baseline of the room(triangulation method) But I dont know how to make a scale for it I looked on the internet but cannot find anything useful. Has anyone done something similar or same for thier forensic module? Please help

hello..i want to do optimisation of a heat pump...how to go about..i know engineering equation solver...what and how many equations in this?..plz help me formulate the equations... i have attached the question below... what assumptions do i need to make....

How is moringa seed powder used to clarify fresh sugar cane juice and how can the shelf life of such juice be incresed without using chemicals?

HI guys. I have a problem with my assignment like: Hexadecimal numbers are made using the sixteen digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F. For a four digit number, the most significant digit is restricted to the digits 7 to C and the least significant digit is restricted to the digits 9 to F.How many numbers are there? Because i am an overseas student, so it is very difficult for me to understand "the most significant digit is restricted to the digits 7 to C and the least significant digit is restricted to the digits 9 to F", can you explain to me,please? Or can you give some examples with this pattern, please? Thank you very much.

Hi im finding it hard to calculate a formula. Can anyone please help me ? t=13.94-15.55/squareroot of 1.8410(1/14+1/15) the answer to this is -3.19 but i keep getting diffrent answers because im confused on how to work out the 1/14+1/15 bit. which step are you supposed to do first ? thanks

Hello, Though the questions that I post in this Homework help section are actually not related to my homework but appear in my 9th STD physics text book with the label "Think It Over", I feel it is appropriate to post them here, because even after much thinking I have not been able to find right explanation. The question is- "The aluminium wires used in the transmission of electric current are not insulated. Why?" Thanks.

Hello, Though the questions that I post in this Homework help section are actually not related to my homework but appear in my 9th STD physics text book with the label "Think It Over", I feel it is appropriate to post them here, because even after much thinking I have not been able to find right explanation. The question- "Is work done when rolling a marble on a frictionless plate?" Thanks.

Hi Anyone good with statistics ? I just want to confirm something, not asking for answers. The standard error of the mean SEM, is it the square root of standard deviation or is it standard deviation divided by the square root of n, the sample number. Please can someone clarify, i have a test and I dont want to do the wrong thing.

Recall that the specific heat of water is 1 cal per gram per degree celsius, and the density of water is 1 gram per cubic centimeter. For this problem, use these values for water, although ocean water is not exactly the same. Assume also: The tropical Atlantic is 3000 km wide and 5000 km from north to south. Finally, assume that the average ocean surface heating is down to a meter depth. 1. How much extra energy is stored in the tropical Atlantic with one degree celsius of temperature increase? 2. How does this value compare with the total annual energy usage in America if we assume that number is a wopping 25,200 quadrillion calories (2.52 x …

Hi i have afew Q and i relly need help with them 1) compare and evaluate the appearance of bone and soft tissue in an MRI scan compared with a conventional X-ray. 2) Explainthe factors influencing the signal intensity in MRI.

why do we use kelvin scale while doing numericals on carnot's engine?