Posts Tagged ‘stretch’

Physics Video: Stretch & Tension Solved on the TI89

Raw Transcript

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
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