I need some quick help with chem/physics

[rogue_eclipse]

Ok I just need to know how to do these :D It's not homework but I'm preparing for an exam so I need to know whether I have been doing them right.

K here they are: (NOTE: '*' means subscript- the little number tha goes to the bottom right of the symbol!)

- calculate number of moles in 100g of Ca(NO*3)*2
-What's the mass of 3.6 mols in SnF*2
-If a 70 kg passenger is riding a car 20m/s and stops in 2.0m What is the force exerted on the Passenger? When the vehicle is stopped...What is the amount of energy?

And: If I give you the symbols, what'S the name and vise versa... AgI, Al*2S*3, CCl*4, SO*2, H*2SO*4, copper (2) fluoride, hydrocyanic acid, benzoic acid, calcium hydroxide, nitrogen dioxide

Thanks Rogue http://www.tombraiderforums.com/images/smilies/wave.gif

[neil4768]

AgI is silver iodide
Al*2s*3 is aluminium sulphide
CCl*4 is carbon tetrachloride
SO*2 is sulphur dioxide
H*2SO*4 is sulfuric acid
copper (2) flouride is CuF*2
hydrocyanic acid is HCN
calcium hydroxide is Ca(OH)*2
nitrogen dioxide is NO*2

[rogue_eclipse]

Thanks a lot Neil http://www.tombraiderforums.com/images/smilies/wave.gif I guess i'm doing well so far :D Are you any good at physics?

Rogue http://www.tombraiderforums.com/images/smilies/jumper.gif

[justin]

I luv physics http://www.tombraiderforums.com/images/smilies/jumper.gif

To approach the car question, i usually write down every part of it first, mass= velocity= all nice and orginaized, then write down the basic formulas, F=ma, E=1/2mv^2, however when the car stops you have to use PE=mgh, i think. Then i'd substitute into the proper equations and figure out methodically. i'd have to dig up my notes to remember everything... and that's alot to remember :confused:

Give me a minute and maybe i'll do the problem out :D

I can't help with moles, i hated that stuff and never bothered to learn it http://www.tombraiderforums.com/images/smilies/bash.gif

[neil4768]

use to be it wqas a long time ago that I last did physics and I can't remember it sorry

[rogue_eclipse]

Originally posted by justin:
I luv physics http://www.tombraiderforums.com/images/smilies/jumper.gif

To approach the car question, i usually write down every part of it first, mass= velocity= all nice and orginaized, then write down the basic formulas, F=ma, E=1/2mv^2, however when the car stops you have to use PE=mgh, i think. Then i'd substitute into the proper equations and figure out methodically. i'd have to dig up my notes to remember everything... and that's alot to remember :confused:

Give me a minute and maybe i'll do the problem out :D

I can't help with moles, i hated that stuff and never bothered to learn it http://www.tombraiderforums.com/images/smilies/bash.gif Hey Justin http://www.tombraiderforums.com/images/smilies/wave.gif Your my new best friend LOL. You seem so enthused over physics that I hope some of it will rub off on me. Yeah please do the car question http://www.tombraiderforums.com/images/smilies/jumper.gif

Rogue http://www.tombraiderforums.com/images/smilies/clown.gif

[galaxia2999]

what grade are you in rogue? i'm learning similar stuff but not that hard, i'm not sure.

[justin]

Bare with me as I haven't done this in a while, and i can't find my notes, and my numbers seem off to me, but this is what i got:

m=70 kg

v=20 m/s

d=2 m

v_f is final velocity, v_i is initial velocity

using: v_f^2-v_i^2=2*a*d

we get acceleration: 0-20^2=2*a*2

a=-396 m/s^2

Using: f=m*a

We get force: f=70*396

f=27790 N

I can calculate the initial kenetic energy:

KE=1/2*m*v^2

KE=1/2*70*20^2

KE=14000 J

But I can't remember how to solve for energy lost... :confused:

[rogue_eclipse]

Thanks Justin! That's great work http://www.tombraiderforums.com/images/smilies/hug.gif I'm not sure how to read the your first answers though- they seem a little tough to understand with all the symbols like the 0-20 blah blah blah one wher it continues with nubers and lines and stuff. Could you write it out in english? using numbers?

Energy lost? hmmm...I can't remember either. Where are you LAdy Ann?

Thanks again man,
Rogue http://www.tombraiderforums.com/images/smilies/smile.gif

[ 21. January 2004, 02:50: Message edited by: rogue_eclipse ]

[justin]

mass=70 kg

velocity=20 m/s

distance=2 m

using: final velocity squared - iinitial velocity squared = 2 * acceleration * distance

we get acceleration: 0-20 m/s squared = 2 * acceleration * 2 meters

acceleration = -396 m/s squared (or m/s/s)

Using: force = mass * acceleration

We get force: force = 70 kg * 396 m/s squared

force = 27790 Newtons

Does this clear things up? or make them more confusing http://www.tombraiderforums.com/images/smilies/mischievous.gif

[neil4768]

Made sense to me Justin

[rogue_eclipse]

Now what do the little stars mean??? http://www.tombraiderforums.com/images/smilies/tongue.gif

No really, what do they mean :confused:

Rogue http://www.tombraiderforums.com/images/smilies/mischievous.gif

[justin]

sorry http://www.tombraiderforums.com/images/smilies/redface.gif , multiply, i suppose an x would have been more appropriate http://www.tombraiderforums.com/images/smilies/smile.gif

[rogue_eclipse]

it's all good Justin! Thanks a lot guys http://www.tombraiderforums.com/images/smilies/hug.gif

Rogue http://www.tombraiderforums.com/images/smilies/wave.gif

[justin]

No prob rogue http://www.tombraiderforums.com/images/smilies/hug.gif

[SpArKy]

Originally posted by neil4768:
AgI is silver iodide
Al*2s*3 is aluminium sulphide
CCl*4 is carbon tetrachloride
SO*2 is sulphur dioxide
H*2SO*4 is sulfuric acid
copper (2) flouride is CuF*2
hydrocyanic acid is HCN
calcium hydroxide is Ca(OH)*2
nitrogen dioxide is NO*2MY god someone knows there stuff neil! http://www.tombraiderforums.com/images/smilies/redface.gif

[neil4768]

Got an A in my O level for chemistry ;)