can anyone do these calculus problems

can anyone do these calculus problems

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moddy

Original Poster:

3 posts

131 months

Monday 13th May 2013
quotequote all
problem 1.

The expression f(t)=10t^2 x sin(2t) represents the work done in kJ by a mechanism on a canning plant against time. By using the process of integration, determine the power dissipated between 1 and 1.3 seconds after the device starts to function.

By the way, f(t)=10t^2 x sin(2t), with the ^ means to the power of 2. Just cant put the equation in correctly as its an e-mail.

Problem 2.

The function Ln((5t^3 - 6t)^3) represents the position of a lever on a mechanism at some point in time. Differentiate the function to determine its velocity 3 seconds after it starts to move.

thanks

tank slapper

7,949 posts

283 months

Monday 13th May 2013
quotequote all
Homework?

The first one can be solved using integration by parts. The second one you need to use the chain rule and substitute the given value of t.

moddy

Original Poster:

3 posts

131 months

Monday 13th May 2013
quotequote all
havent got a clue???

homework! I'm 51

thanks

Zad

12,698 posts

236 months

Tuesday 14th May 2013
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denchy1

28 posts

139 months

Tuesday 14th May 2013
quotequote all
moddy said:
problem 1.

The expression f(t)=10t^2 x sin(2t) represents the work done in kJ by a mechanism on a canning plant against time. By using the process of integration, determine the power dissipated between 1 and 1.3 seconds after the device starts to function.

By the way, f(t)=10t^2 x sin(2t), with the ^ means to the power of 2. Just cant put the equation in correctly as its an e-mail.

Problem 2.

The function Ln((5t^3 - 6t)^3) represents the position of a lever on a mechanism at some point in time. Differentiate the function to determine its velocity 3 seconds after it starts to move.

thanks
Problem 1.
[-5t^2 x cos(2t) - int(-10tcos2t)]
[-5t^2 x cos(2t) - (-5tsin2t - int(-5sin2t))]
[-5t^2 x cos(2t) + 5tsin2t + 2.5cos2t]

therefore sub in 1.3 and 1 you get then take the value from at t=1 from that at t=1.3 you get 2.86kW.

Problem 2.

dx/dt = 9(-2+5t^2)(-6t+5t^3)^2 = (-18+45t^2)(-6t+5t^3)^2

dp/dx= 1/x =1/(5t^3 - 6t)^3

dp/dt=dp/dx*dx/dt = (18-45t^2)/(6t-5t^3)

sub in t=3 v=dp/dt= 3.3m/s


tank slapper

7,949 posts

283 months

Tuesday 14th May 2013
quotequote all
There is something not right about the first question, unless I have missed something obvious. Power is the time derivative of work not the integral, so although denchy's integration of the expression is correct, I don't think it gives a meaningful answer. If the question gave the expression as that for power and asked you for the work done between the times, then denchy's answer would be the way to do it.

Where are the questions from?

moddy

Original Poster:

3 posts

131 months

Tuesday 14th May 2013
quotequote all
Thanks to everyone who gave up their time and helped me.

denchy1

28 posts

139 months

Tuesday 14th May 2013
quotequote all
tank slapper said:
There is something not right about the first question, unless I have missed something obvious. Power is the time derivative of work not the integral, so although denchy's integration of the expression is correct, I don't think it gives a meaningful answer. If the question gave the expression as that for power and asked you for the work done between the times, then denchy's answer would be the way to do it.

Where are the questions from?
Yep you are correct, didnt read it properly, was late. Question should say expression for Power, intergrate to find the work done.

moreflaps

746 posts

155 months

Friday 17th May 2013
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Yes I can. Can you?

Cheers

aw51 121565

4,771 posts

233 months

Saturday 18th May 2013
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Elaboration would be helpful wink .

And no, I can't frown . Masters postgraduate, but this stuff is very much dark arts hehe ...