Need Help with AP Physics Free Response Questions?

In summary, the problem is to find the force acting on an object due to an applied acceleration. Integration is the wrong method. v is the impulse, which is the momentum difference between the initial and final states.
  • #1
harmonicmotion
51
0

Homework Statement



Homework Equations





The Attempt at a Solution

 
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  • #2
http://http://www.collegeboard.com/prod_downloads/ap/students/physics/physics_c_m_frq_02.pdf [Broken]

PLEASE HELP
 
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  • #3
1. You must state the problem
Yes, that means posting the problem here. At Pf.

2. You must show your own work.
 
  • #4
http://http://www.collegeboard.com/prod_downloads/ap/students/physics/physics_c_m_frq_02.pdf" [Broken]
 
Last edited by a moderator:
  • #6
its the first question
 
  • #7
the second link works i think
 
  • #8
can you try it and let me know if i should type it
 
  • #9
Okay second link works, so what have you done so far? :smile:
 
  • #10
are you still there
 
  • #11
Indeed, what have you done so far?
 
  • #12
i did a) and got 500 kg
 
  • #13
This isn't a chat room, it takes a few minutes before you get responses.
 
  • #14
on b i am trying to integrate and got x=(8/5)ln{1+5t}
 
  • #15
i really do not think that is correct though
 
  • #16
on a)+b), you are correct.
 
  • #17
harmonicmotion said:
i really do not think that is correct though

But it is.
 
  • #18
is integration the wrong method?
 
  • #19
oh ok thank you, I am having trouble with c and d though
 
  • #20
harmonicmotion said:
is integration the wrong method?

Eeh, do you even take time to read the replies you get??

Slow down a bit, will you?
 
  • #21
what is the best method to use
 
  • #22
harmonicmotion said:
oh ok thank you, I am having trouble with c and d though

Ok, now, is there some other quantity you can calculate by means of which you can calculate the force acting upon the object?
 
  • #23
I'm sorry i think my computer is on delay because the messages don't come up until after i send something else
 
  • #24
mass times acceleration?
 
  • #25
harmonicmotion said:
mass times acceleration?

Agreed!

So, how can you find acceleration? (you already know mass)
 
  • #26
hdhdkshhfsdhkf
 
  • #27
dv/dt? could that be used?
 
  • #28
use
Fnet=ma
 
  • #29
harmonicmotion said:
dv/dt? could that be used?
Sure!
Isn't that what acceleration is, after all?
 
  • #30
hjkshdgytu
 
  • #31
sorry for the random letters your responses don't come up on my comp otherwise
 
  • #32
wait so would dv/dt just be 8/(1+5t)
 
  • #33
hsjsysgdsd
 
  • #34
harmonicmotion said:
sorry for the random letters your responses don't come up on my comp otherwise

I understand.

Now, as for d) assuming you manage c), it is perhaps simplest to remember that the impulse over a time interval equals the change in momentum over that interval.
 
  • #35
dhdyegstdff
 

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