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Mathematics 21 Online
OpenStudy (anonymous):

can someone please explain this step by step to me?

OpenStudy (anonymous):

@amistre64

OpenStudy (anonymous):

@ikram002p

OpenStudy (ikram002p):

s(t) = 5cos(t) − sin(3t) first derivative gives the velocity , right ? second derivative gives the acceleration , could u try it please ?

OpenStudy (anonymous):

find out derivative?

OpenStudy (anonymous):

is it 0

OpenStudy (ikram002p):

how ?

OpenStudy (anonymous):

i dont really know second derivatives, this is a practice test for the module and i like learning about it before i actually do it and im completely confused. could you write the steps out fo me

OpenStudy (ikram002p):

first derivative is s'(t) can u find it ?

OpenStudy (anonymous):

-5sin(t)-3cos(3t)

OpenStudy (anonymous):

@ikram002p

OpenStudy (anonymous):

can you plz write steps

OpenStudy (ikram002p):

yes , now second derivative is the first derivative of -5sin(t)-3cos(3t) :)

OpenStudy (ikram002p):

now take derivative for -5sin(t)-3cos(3t)

OpenStudy (anonymous):

9sin(3t)-5cos(t)

OpenStudy (ikram002p):

yes :) so the velocity would be the first derivative of the position function v(t)=s'(t)=-5sin(t)-3cos(3t) while the acceleration is given by the second derivative of the position function or the first derivative of the velocity function like this a(t)=v'(t)=s''(t)=9sin(3t)-5cos(t)

OpenStudy (ikram002p):

back to ur question , ` What is the acceleration of the particle at time t = π seconds?` you found acceleration , which is a(t)=9sin(3t)-5cos(t) now all u need is to find a(π ) :) , good so far ?

OpenStudy (anonymous):

yess

OpenStudy (ikram002p):

let me know if u have doubt , and if u saw some weird symbols just refresh the page :)

OpenStudy (anonymous):

sorrry openstudy signed me out @ikram002p what do i do next?

OpenStudy (ikram002p):

a(t)=9sin(3t)-5cos(t) now all u need is to find a(π ) :)

OpenStudy (anonymous):

so replace 2 with pi? i dont get it ..

OpenStudy (anonymous):

t*

OpenStudy (anonymous):

like i dont get what you mean..

OpenStudy (ikram002p):

yes replace :O which part u dont understand ?

OpenStudy (anonymous):

so its going to be 9sin(3pi)-5cos(pi)

OpenStudy (anonymous):

im getting a weird answer

OpenStudy (anonymous):

Yes, you plug in pi in the second derivative, what did you get?

OpenStudy (anonymous):

-3.51

OpenStudy (anonymous):

which makes no sense

OpenStudy (anonymous):

Mhm, not sure how you did that, what is sin(3pi) ?

OpenStudy (anonymous):

Go back to trigonometry, and the special triangles :)

OpenStudy (anonymous):

You should get a whole number

OpenStudy (anonymous):

0?

OpenStudy (anonymous):

Right!

OpenStudy (anonymous):

what is cos(pi)?

OpenStudy (anonymous):

-1

OpenStudy (anonymous):

Right right! So -5*-1? :)

OpenStudy (anonymous):

5 (:

OpenStudy (anonymous):

There you go!

OpenStudy (anonymous):

thank you !!

OpenStudy (anonymous):

In calculus, the starting process is the calculus part mostly, and then towards the end it slowly goes back to high school math ;). Just a little secret.

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