dash00

depends what level of maths you do, i was confused by using f(x) as opposed to y= when we were first taught to use it, which was at the begining of year 11.

Thank you so much, Glider. Thais is very helpfull and i can understand the process now a great deal better now. However, some of the information you gave is beyond what is expected of me at the moment (highschool bio), a more indepth explanation makes the process easier to understand than a greatly simplified one which leaves out some critical aspects of it. thanks.

I had a definition in my chem text book that a salt is any compound which doesnt fall into the categories of either acidic or basic is that correct or?

hey you seem to know your stuff, instead of making a new topic i was wondering if i could ask my question here.. Do you think you could possibly explain, in simple terms (if you can) the nerve impulse transmission process to me? My text book explains it in such a way that it seems very confusing to me that help would really be appreciated, thanks!

being a smart ass accomplishes what exactly?

2. A force of 20 N acts for 8 seconds on a mass of 60Kg. What is the (a) acceleration, (b) final speed, © average speed, (d) distance covered during the 8 seconds. a) F= m *a : a = 20/60 =1/3 m/s/s. b) use v = u + at: v = 0 + (1/3)*8. c) use x = (u+v)t : x= (0+ 2.67)*8 = 21.33 m ; avg speed = dist. /time = 21.33/8. d) already found this in q. c, maybe i took a long way. 4. Calculate the kinetic energy of a car of mass 1200Kg travelling at 25 m/s. If it brakes to rest at 40 meters, calculate the braking force. kinetic energy = 1/2 m*v^2 = 375000 J. i would use x = (u+v)*t to give: 40 = (25+ 0) t, t = 40/25 = 1.6s, The change in momentum of the car is: p=mv = 1200*25 = 30000 kgm/s . F= change in momentum/ time = 30000/1.6 = 18750 N. I suspect they want you to do this problem a different way because they asked you to calculate the Ek but i am doing alot about momentum in physics atm so i would use this way and i cant think of another right now. 5. How much heat is released by the combustion of 4Kg of petrol of calorific value 46 MJ/kg? if one kg gives 46 MJ (million Joules) , then 4kg of petrol must give how many MJ? 6. A sonar beam is radiated from a ship and an echo is received after 0.9 seconds. If the speed of sound in the water is 1400 m/s, how far away is the reflecting surface? for this use speed = distance/time. speed = 1400m/s and time = 0.9 s, therefore distance = 1400 *0.9 = 1260 m, however, this is the distance traveled by the sonar beam, not the distance of the ship to the bottom, which is half this distane for your answer. incase you were unfamiliar, in the motion equations v = final velocity, u = final velocity and x = displacement sorry if there is any mistakes there, hope it helps ps. These really aren't confusing problems, you should read more of your text book to understand them.

Im just a highschool student myself so im sure people around here know more than i do but the mole ratio is 1:1 --> 1 i thought. so you do not add the 0.05L*0.1 M = 0.005 moles together, i believe. To get the molar heat of reaction, try 334.4 /0.005 ! hope thats a help, maybe someone else can explain it more clearly to you than i could the reason for doing this.

firstly, thanks alot guys for your responses and taking the time and effort to help me out. i got the answer 7200 as well (g= 10 , lazy ) but when i saw how far out i was from the teachers answer i thought it was something more complicated than summing them. Suppose this car was dropped of a cliffe, wouldnt it only require a force of mg = 12000N to stop it? i guess the answer is wrong (61000N)! ( it is just the teacher who writes up the answers on back of sheet, mistakes arent too out of the ordinary) thankyou very much edit: btw, to work out the 6000N i used the motion equation x= (u + v)t where time was the unknown before using Favg= change in momentum/time did you guys use the same method or a different way? ps. what is a lepton?

Thanks for the reply. i realised thats wat i needed to and worked out the component of the force thats in the direction of travel to be 1200 N (is that right?) but once i'd done that i wasnt sure how to put it all together, so i came here. Could you please tell me how to go about working it out after this stage? i have spent a fair bit of time trying to figure out wat im missing so help would realy be appreciated if you would be so kind. answer provided is 6.1 *10^4 N btw. thanks

Please take a minute to help me out with highschool phys prob. A car of mass 1200kg is travelling down a hill with an incline of 1 in 10. Speed = 30 m/s when a constant braking force was applied. The car stopped after travelling 90 m down the incline. What was the magnitude of the constant braking force applied? my answer for it is incorrect . i got 6000N, but i didnt take into account the fact that it is on an incline at all lol, i had a go but wasnt sure how to thanks for your help in advance im sure this will be childs play for most of you! edit: sorry people, i didnt realise there was the 'homework help' section here, i just registered tonight, sorry again.