Need Help with AP Physics Free Response Questions?

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SUMMARY

This discussion focuses on solving AP Physics Free Response Questions, specifically from the College Board's Physics C exam. Participants emphasize the importance of stating the problem clearly and showing work, as required for effective assistance. Key concepts discussed include the application of Newton's second law (F=ma), integration for calculating velocity and acceleration, and the relationship between impulse and momentum. The conversation highlights common pitfalls in problem-solving and the necessity of differentiating functions to find acceleration.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with calculus concepts such as differentiation and integration
  • Knowledge of momentum and impulse in physics
  • Ability to interpret and analyze AP Physics Free Response Questions
NEXT STEPS
  • Review AP Physics C exam format and scoring guidelines
  • Practice solving AP Physics Free Response Questions from previous exams
  • Study the relationship between impulse and momentum in detail
  • Learn advanced integration techniques relevant to physics problems
USEFUL FOR

Students preparing for the AP Physics C exam, educators teaching AP Physics, and anyone seeking to improve their problem-solving skills in physics, particularly in the context of free response questions.

  • #31
sorry for the random letters your responses don't come up on my comp otherwise
 
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  • #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
 
  • #36
harmonicmotion said:
wait so would dv/dt just be 8/(1+5t)

No, that is v itself!

You must differentiate that expression to get the acceleration.
 
  • #37
isnt impulse also force times the change in time
 
  • #38
sorry i still can't figure out c
 
  • #39
harmonicmotion said:
isnt impulse also force times the change in time
Only if the force is constant.
If it is not constant, you must perform the integral of F over time.
Happily, this equal to the change of momentum over that time.
 
  • #40
hdysudjfgf
 
  • #41
harmonicmotion said:
sorry i still can't figure out c

Well, what is v?

differentiate that function!
 
  • #42
for c i got (500)(-40)(1+5t)^-2
 
  • #43
Oops!
Remember that the mass of the system consists of BOTH the masses, i.e, 1000+500=1500.
 
  • #44
gyhtdesrehh
 
  • #45
so for 500 i put 1500 and then its right?
 
  • #46
harmonicmotion said:
so for 500 i put 1500 and then its right?

That is correct.
 
  • #47
hyujiklofddss
 
  • #48
so d is (mv(final)-mv(initial))/(time)
 
  • #49
No, that would give you the average FORCE over that time interval.
Do not divide with time; the impulse is just the momentum difference.
 
  • #50
hyhndhstsy
 
  • #51
so 3000?
 
  • #52
hyujhjyuhj
 
  • #53
mkinjubhyt
 
  • #54
wait sorry i messed up
 
  • #55
-10909.09?
 
  • #56
nhymjumjuy
 
  • #57
harmonicmotion said:
wait sorry i messed up

Indeed you did.

You should get:

I=1500*(\frac{8}{11}-8)=-1500*\frac{80}{11}
 
  • #58
asdfghjkl;
 
  • #59
oh ok thank you so much!
 
  • #60
harmonicmotion said:
oh ok thank you so much!

You're welcome! :smile:
 

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