# Homework Help: Help for Dynamics! Continuous Motion

1. Jul 30, 2011

### JamieShumJr

Can someone tell me how to obtain the figure in red circle? I've trying out on my own but can't get that.

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2. Jul 30, 2011

### tiny-tim

Welcome to PF!

Hi JamieShumJr! Welcome to PF!
You're asking why is ∫ (0.8t + A)-1/2 dt = (2/0.8)(0.8t + A)1/2

apply the https://www.physicsforums.com/library.php?do=view_item&itemid=353" twice

if you differentiate the RHS, you get an extra 0.8 from the t, and an extra 1/2 from the power, = (0.8/2)

Last edited by a moderator: Apr 26, 2017
3. Jul 30, 2011

### JamieShumJr

Re: Welcome to PF!

Thanks a lot! I neglected the 0.8 during the integration. Got it already. Forgotten the basic rule of integration.

Last edited by a moderator: Apr 26, 2017
4. May 19, 2013

### mintz

may i know from same question as above shown, how to get the -1/60 at the end there?

5. May 19, 2013

### tiny-tim

welcome to pf!

hi mintz! welcome to pf!
the $|^t_0$ at the end of the previous line means you have to evaluate it at t and at 0, and subtract

6. May 19, 2013

### mintz

oh~okie~thanks! i made mistake that evaluate at 0 whole things became 0~
thanks anyway!=D