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hello this is Tom

for EveryStepPhysics.com I write those programs for the TI-89

titanium and other calculators in the TI system

we’re doing this problem here which is a standard problem of

tension and um

let’s get started. Of course we put physics in here with close parentheses

open/close parenthesis so that you get to my

menu press Enter and we

we can scroll down here with the cursor or we can go

up because tension is closer to the the z, I’m going to go to the bottom of the

menu and I’m going to hold the cursor down here

go up to tension there’s tension generally in any problem whatever they ask that’s

what you go to in

my menu if they ask for acceleration you go there if they ask for velocity you go there

if they ask for…um stretch

or whatever they might ask you go that problem in this case we’re

talking about tension and of course they give you in this problem a mass and they

give you

angles two angles

and they give you the distance apart so we’re going to choose number seven

and we have to press alpha before we press anything we go

alpha 800 is the mass

in kilograms

I give you these in case whatever they

give you you have a choice and the angle is

L first angle is alpha 18, and the other angle is

alpha 10

and ask if they gave you the distance apart

the distance apart generally doesn’t have anything to do with the tension because

the angles determine the tension

and the distance apart a lot of times they throw you off with that

in this problem they ask you for extra credit to get the stretch of the

strings so I would use the distance in this case but so we say

yes distance is given then I gotta go alpha

18, you notice that they try to trick you again physics they love to trick you

they gave you 18 distance the same thing as the first

angle so you know

they could give you twenty-two or something for the distance and

make it completely different so you would not be confused but

they love that in physics

and of course you got meters so you gotta go number two in

meters I show you what you’ve entered here’s 800 kilograms 18,

18 angle 10 angle and 18 distance apart

I say it’s okay

So we’re going to move on I show you a picture of it here’s the 18 angle the 10 angle

tension one tension 2 and tension 3 is the cable that holds the

mass and so we have to solve this with 2

equations I show you the first equation here

and

we substitute that into the into the other equation

write all this down on your paper don’t put a substitute equation in there were

but.. but just put the

equations on your paper and so the

tension of t2 which would be on that side on of the

picture is 15898 newtons

and the t1

tension is 16,463 Newton’s

notice the uh, the credit that you get on this problem

in other words there’s just 10 points for doing this one here

which is just the tension on the corners mass times acceleration

and thats 7848

you got 10 points for this the other ones are five points apiece five points and

there’s a

so we found the tensions in each

system there and then I go to the

stretching of the string notice we have a,

b, c which is this part of the triangle

and d and e we have 10

degrees here notice the this angle here would be complimentary which is eighty

this is 18 so this is 72 sometimes they give you these angles too

ah, but anyways we need to find the stretch so we need to find the distance of

this which is the hypotenuse and this which is the hypotenuse of the

10 angle and so

tangent of, of times b would equal

the c a+b is equal to 18 that’s the total distance apart

and so b would be 18 minus a

and just write this stuff down you can take your time and look at it if you really wanna learn it

but I was always interested in passing tests

not completely learning physics and so the

a above that a 6.33 units I use units because I don’t know if I gave you centimeters or

whatever inches or whatever they might trick you with but anyways that portion of

the triangle a is 6.33 and then we

subtract that from the 18 we get 11.7 units and then the hypotenuse

of d

which is 6.66 units and then the hypotenuse

of a 10 degree angle is 11.8 units

we add those together 18.5 minus

what we started with so the stretch is .506 units

Pretty neat huh? EveryStepPhysics.com go to my site buy my programs and pass

your physics class and also

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