June 2010: Physics

<p>for the wave gen i think it said that the velocity of the waves changes. F never changes so the wavelength does change</p>

<p>Oh I was sure about my answer to that. The eqn that relates it is s1/lam1 = s2/lam2 because freq doesnt change but I can’t remmber the values. </p>

<p>I also got I and II for the one with “which of these could make the net force zero with three forces?”</p>

<p>For another, do you remember putting work as the only nonvector quantity. I got this.</p>

<p>

</p>

<p>Yes I can confirm that work was the only nonvector quantity.
The one with three forces was I only (vector sum = 0), others didn’t work</p>

<p>for the net force zero it said what does a net force of zero tell you for sure
the only hting u can know for sure is that “vector sum = 0”</p>

<p>

</p>

<p>Thats what I got.</p>

<h2>Consolidated List ~37/75 Questions (Half the test)</h2>

<p>v/2L is fundamental frequency for string fastened at two ends
Resonance was an answer
For the graph given about a wave:
–period = 0.01s
–amplitude = 4
–wavelength = 6
For the graph given about potential energy versus distance:
–potential energy at x1 = a
–kinetic energy at x1 = b
75) B0 or R isnt necessary for emf *<em>(split)
beta particle emission question: nuclear mass stays the same
radioactive decay with half lives after 90 days = 8
Telephone messages —> visual images on screen = fiber optic cables (Confirmed)
students record distance travelled: 10.77 is average velocity / 13.4 m in fifth second (</em>split)
two magnets are next to eachother:
–1st question: either one or both are permanent.
–2nd question: both are permanent
Q = cv = 20x10^6
for 73) current is same (E) I1 = I2 = I3 (current stays same in series circuit)
for 74) use resistance eqn. R = PL/A answer was r3(thinnest)>r1(medium)>r2(fattest)
for the beginning like numbers 6-8 given graphs:
–relationship between mass and energy = E = mc^2 = straight line (B)
–relationship between freq. and energy = E=hf = straight line (B)
–intensity of monochromatic blue light (D which is straight line with positive x intercept) (Confirmed)
optics question with converging lens: same size upside down
for 72) f/cos thetha
71) F = 40 N
First few questions:
–1) momentum of II is greater
–2) momentum is same
–3) momentum is same
optics question with plane mirror at an angle: image is virtual and not inverted
Least affects static shock when getting out of car: whether the engine is on (Confirmed)
Pulley with 2 masses of 50 N each and in equilibrium: Force on the rope is 50 N
The efficiency one being 40% (500K and 300K)
B for the field line diagrams w/ two opposite charges
30m for dropping something off a cliff
“II only” for the one with large and small boxes with temperature transfer
For the 5 diagrams as choices with a satellite orbitting a planet. Mass and Radius varied.
–First problem, asked which had greates grav. force = answer E (m=2M r=R)
–Second problem = E (m=2M r=R)
Linear Expansion problem:Temp raised from 20 to 22 over to 20 to 30. deltaT raised 5x, so L raised 5x, and the answer = 0.015 cm
Rutherford Experiment problem: The size of nucleus was significantly smaller than that of the atom
Elevator problem: I only
Which of these could make the net force 0: I and II only (I got “vector sum=0, and that some could be in the same direction”, but not that they could be the same magnitude)
Work is the only nonvector quantity
Wave generator (deep –> shallow): The eqn that relates it is s1/lam1 = s2/lam2 because freq doesnt change : Answer = velocity of the waves changes
Which waves can interfere(sound somethign somthing) Answer: I, II, and III</p>

<p>and BACK to the 2 magnet bar thing problem
the first part said 2 sides are attracted, the answer is one or both is a magnet
the second part says that the other two sides are attracted to each other- either one could sstill be a maget or not a magnet</p>

<p>For the net force 0 dont u know that 2 must be in the same direction in order to oppose 1 force. I mean it cant be any other way… so like 3N and 2N on one side and 5N on other side (follows I and II)</p>

<p>

But why? dont both have to be permanetn magnets if both magnets have different poles?</p>

<p>

</p>

<p>In order for two specific pairs of sides to attract each other, both have to be magnets. If one were a magnet and one say a piece of metal, then the BOTH of the sides of the piece of metal would attract to both of the sides of the magnet.</p>

<p>Therefore, the answer for #2 of the magnet problem is that both have to be magnets.</p>

<p>they could be evenly spaced out to cancel
but i thought that problem was the other way around from what you all are saying…
i remember it asking what conclusions can be definitively drawn from having a net force 0 between 3 vectors</p>

<p>

</p>

<p>Yes! I think you are right! I now remember choosing two answers for that one. Do you remember what choice II and III were?</p>

<p>to evillon
it never said that either side was NOT attracted to the other
all it said is that “this end was attracted here” and then “this other end is attracted to this other end”
never asaid only attracted to</p>

<p>I know III was bogus. II was the 2 forces must be in same direction.</p>

<p>

</p>

<p>I think it’s implied when it says “Side A is attracted to side B and side C is attracted to side D” – But yeah, I can see where you are coming from, you may be right.</p>

<p>Okay I’ll put a split on that one. </p>

<hr>

<h2>Consolidated List ~37/75 Questions (Half the test)</h2>

<p>v/2L is fundamental frequency for string fastened at two ends
Resonance was an answer
For the graph given about a wave:
–period = 0.01s
–amplitude = 4
–wavelength = 6
For the graph given about potential energy versus distance:
–potential energy at x1 = a
–kinetic energy at x1 = b
75) B0 or R isnt necessary for emf <strong>(split)
beta particle emission question: nuclear mass stays the same
radioactive decay with half lives after 90 days = 8
Telephone messages —> visual images on screen = fiber optic cables (Confirmed)
students record distance travelled: 10.77 is average velocity / 13.4 m in fifth second (*split)
two magnets are next to eachother:
–1st question: either one or both are permanent.
–2nd question: both are permanent (</strong>split)
Q = cv = 20x10^6
for 73) current is same (E) I1 = I2 = I3 (current stays same in series circuit)
for 74) use resistance eqn. R = PL/A answer was r3(thinnest)>r1(medium)>r2(fattest)
for the beginning like numbers 6-8 given graphs:
–relationship between mass and energy = E = mc^2 = straight line (B)
–relationship between freq. and energy = E=hf = straight line (B)
–intensity of monochromatic blue light (D which is straight line with positive x intercept) (Confirmed)
optics question with converging lens: same size upside down
for 72) f/cos thetha
71) F = 40 N
First few questions:
–1) momentum of II is greater
–2) momentum is same
–3) momentum is same
optics question with plane mirror at an angle: image is virtual and not inverted
Least affects static shock when getting out of car: whether the engine is on (Confirmed)
Pulley with 2 masses of 50 N each and in equilibrium: Force on the rope is 50 N
The efficiency one being 40% (500K and 300K)
B for the field line diagrams w/ two opposite charges
30m for dropping something off a cliff
“II only” for the one with large and small boxes with temperature transfer
For the 5 diagrams as choices with a satellite orbitting a planet. Mass and Radius varied.
–First problem, asked which had greates grav. force = answer E (m=2M r=R)
–Second problem = E (m=2M r=R)
Linear Expansion problem:Temp raised from 20 to 22 over to 20 to 30. deltaT raised 5x, so L raised 5x, and the answer = 0.015 cm
Rutherford Experiment problem: The size of nucleus was significantly smaller than that of the atom
Elevator problem: I only
Which of these could make the net force 0: I and II only (I got “vector sum=0, and that some could be in the same direction”, but not that they could be the same magnitude)
Work is the only nonvector quantity
Wave generator (deep –> shallow): The eqn that relates it is s1/lam1 = s2/lam2 because freq doesnt change : Answer = velocity of the waves changes (can’t remember values but used that equation to get ans = 3.2)
Which waves can interfere(sound somethign somthing) Answer: I, II, and III</p>

<h2>relationship between freq. and energy = E=hf = straight line (B)</h2>

<p>Isn’t it the straight line shifted to the right since e = hf - (work function)?</p>

<p>And for the wave generator question, my answer was 3.2</p>

<p>yes to both</p>

<p>What was the answer to the negatively charged rod and X and Y ends of a (magnet?)?
I eliminated all but the voltage answer, so I just put that.</p>

<p>I put the voltage one (E) as well.</p>

<p>it was just a piece of metal, not a magnet
and i got that they botha had the same net positive charge because the protons dont move when the neg. rod comes close</p>