I think the solution for the part b has some problem. To calculate the new center of mass, the boy's new position should not be 4.24m as shown in the solution. While the boy walks across the raft, the raft is also moving. The other corner already shift towards the left. I believe the final position of the boy relative to the raft's center should be (x + 2.12) m. Using this in the CM calculation, x = -0.424 m. So the raft moved 2.544m in the direction opposite the boys's displacement.

Thanks for your attention. 

2) Can someone please explain the answer for 5.33?  I got 1, but the book says 3 is the correct answer. 

A: Weighs 2 kg, 5 m/s to 2 m/s - Change in KE = 1/2*2*(2*2-5*5) J = -21 J

B: Weighs 3 kg, 3 m/s to -3 m/s - Change in KE = 1/2*3*(3*3-(-3)*(-3)) J = 0 J

C: Weighs 5 kg, 5 m/s to 6 m/s - Change in KE = 1/2*5*(6*6-5*5) J = 27.5 J

D: Weighs 4 kg, -1 m/s to 2 m/s - Change in KE = 1/2*4*(2*2-(-1)*(-1)) J = 6 J

The answer says that the ranking is C, B, A, D, which doesn't make any sense to me given the calculations I made. Can someone please explain what I did wrong, or clarify the question?

A critically damped simple harmonic oscillator starts from an amplitude of 5.0 cm and comes to rest at equilibrium 3.5 sec later. The simple harmonic oscillator is made of a .58 kg mass hanging from a spring with spring constant 150 N/m. Assuming the friction force is in the vertical direction, how big is the friction force?

The given answer does not specify which part of the electroscope is grounded, but since only the knob is accessible, the rest being in the glass bulb, the implication is that the knob is grounded.   It seems to me that grounding the knob would cause electrons to flow from earth onto the positively knob and when the ground is broken and the rod removed the result would be a negatively charged electroscope.

I read the given answer, and I am still confused. I don't know how you are supposed to get 0 m/s for the velocity of the block. Why do you use negative impulse for the block when you use positive impulse for the sphere? When do you use negative impulse? Why don't you use the mass of the entire system, which would be the block and the ball? This has to do with it being elastic/inelastic, but I don't know how you can tell from an impulse graph.

Help??

Thanks!

AP1 Dynamics 19.pdf

Name: AP Physics 1 2017 Free Response Solutions
Category: Exam Prep
Date Added: 2017-08-20
Submitter: FizziksGuy

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Name: AP Physics 2 2017 Free Response Solutions
Category: Exam Prep
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(A) 3.0x10^-2 N

(B) 3.0X10^0 N

(C) 3.0X10^1 N

(D) 3.0X10^2 N

The explanation says that it takes 0.010 seconds for the baseball to accelerate from 0 m/s to 20 m/s, but that doesn't really match up with the question... Is the wording a little weird?

Name: AP Physics 2 2016 Free Response Solutions
Category: Exam Prep
Date Added: 2016-05-15
Submitter: FizziksGuy

Walk-through of the 2016 AP Physics 2 Free Response Questions. Questions can be found at http://apcentral.collegeboard.com/apc/members/exam/exam_information/225439.html.

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Name: AP Physics 1 2016 FRQ Solutions
Category: Exam Prep
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Name: Reflections on the 2015 AP Physics 1 Exam Free Response Questions
Category: Exam Prep
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3:21 Weight and mass are not the same
3:32 Design an experiment
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Rotational Motion Packet

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  mpowlin
• Submitted
  12/17/2015
• Category
  Rotational Motion

Name: Introduction to Kinetic Energy with Example Problem
Category: Work Energy & Power
Date Added: 2015-11-19
Submitter: FizziksGuy

Name: AP Physics 1 - Angular Momentum
Category: Rotational Motion
Date Added: 2015-11-19
Submitter: FizziksGuy

Brief introduction to angular momentum for algebra-based physics courses such as AP Physics 1.

Conservation of Energy AP Problems

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• Submitted
  11/17/2015
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Energy and Momentum Packet

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• Submitted
  11/17/2015
• Category
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