June 2010: Physics

<p>hmmm your argument is very valid but im still confused as to the formula U = Q - W
:S, does this formula have no hold in this situation at all?</p>

<p>Guys, that was hard as hell haha. I finished practice tests with an average of 10 minutes left, but I couldn’t even finish the real thing in time. It might’ve been because I was under pressure and I was extra careful in making sure I filled in the right bubbles, but yeah haha, not good not good. What do you guys expect the curve to be? - how many for an 800? And - how many for a 750?</p>

<p>For the change in kinetic energy, they gave mass, acceleration, and displacement. I used kinematics to find Vf^2-Vo^2=2aΔx because the change in kinetic energy would be ΔKE=1/2m(Vf^2-Vo^2)=1/2m(2aΔx)=60J</p>

<p>Does anyone remember getting “0 m/s” for the velocity of the black traveling east after the collision? Also, does anyone remember the questions about the pendulum…?</p>

<p>yeah i got 0 m/s! since the momentum of the other block was the same as momentum before.</p>

<p>Tried to get rid of the repeats…</p>

<hr>

<h2>Consolidated List 65/75 Questions </h2>

<p>v/2L is fundamental frequency for string fastened at two ends
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
the merry go-around is spinning at the speed of 1/2 pi
75) B0 isnt necessary for emf (Confirmed)
the centripetal force decreased by a factor of 4 (F/4)
acceleration (mass?) of the pushed object is 5x 10^6
beta particle emission question: nuclear mass stays the same
the constant force applied on the 5 kg object was 30 N
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 (Confirmed)
two magnets are next to eachother:
–1st question: either one or both are permanent.
–2nd question: both are permanent (<strong>split)
RC Circuit - Q = cv = 20x10^6
change in kinetic energy of the object is F * d = 60 J
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 (Straight horizontal line) (Confirmed)
optics question with converging lens: same size, inverted
for 72) f/cos thetha
71) Force of friction with 100N force applied was F = 40 N
First few questions:
–1) momentum of II is greater
–2) momentum is ame
–3) momentum is same
optics question with plane mirror at an angle: image is virtual and not inverted (twist page and deal with it as a normal mirror question)
The resulting force of attraction between the two moved is 1 x 10^4 (originally 4e4)
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
80m for dropping something off a cliff
“II only” for the one with large and small boxes with temperature transfer (Confirmed)
For the 5 diagrams as choices with a satellite orbitting a planet. Mass and Radius varied.
–First problem, asked which had greatest 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
Waves interfere with each other and get diffracted at the two slits.
Switched I and III add up to the least resistance, thus the greatest current
Elevator problem: I only
Which of these could make the net force 0: I only
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 light radio) Answer: I, II, and III
Negatively charged rod and X and Y are ends of a piece of metal: Answer: voltage / net force = 0 (</strong>split)
Area under F vs t curve = impulse
Two different frequencies: beats (Confirmed)
Question underneath that: resonance (Confirmed)
Question underneath that: quality (Confirmed)
Center of mass of the frame: point D
Graph of ax + b is linear with a positive slope and y-intercept
The range of the perimeter of the rectangle where the sides were known to a ±.1 value was a range 13.6 to 14.4
A person throws an objects in the air, which graphs represents velocity v.s. time
–answ: the graph with the positive y-intercept that slopes down and intersects with x-axis
Which of the following stays constant for (object)?
–answ: acceleration
What is not true regarding the beta particle?
–answ: Minimum potential energy
A ruler attached to table undergoes simple harmonic motion
An atom emits a beta particle –> another particle must also be emitted
Acceleration of ball released from rest is same as ball thrown
Maximum current you could get from something with P=10 watts and a R= 20 ohms is 1/(sqrt2).
0 m/s velocity of block after collision</p>

<p>Wow I got quite a few right without actually knowing the physics behind it
See in South Africa, we’re so used to getting screwed over in government exams we’ve developed the ability to make extremely educated guesses…</p>

<p>Hello! I was just wanted to ask those who have taken the physics subject test, whether I would be prepared to take it in October, with some studying. </p>

<p>I have completed a regular Physics course this year, but there were a couple sections that we never went over (heat and thermodynamics, magnetism, optics (we went over waves a bit), and modern physics.) I’m fairly comfortable with Mechanics. So would I be prepared to take the physics subject test in October if I taught myself those sections?</p>

<p>

</p>

<p>Yes, you would be prepared. I took a 1-year course this year that didn’t cover any of those extra topics you named, and I was fine for the test. The generous curve is there because the writers of the Physics test don’t expect everyone to have learned all those extra topics. Besides, they don’t show up as frequently as the topics you learned during your regular class, so just a little bit of review should leave you primed to nail the test in October.</p>

<p>question about a mercury thermometer and why it rises with heat. I think the answer was that the mercury expands faster than glass</p>

<p>

Thank you, evillion! That was really helpful. I looked up the reviews for the different prep books, and it looks like Barron’s and Kaplan’s were not as well liked as the Princeton Review. Any suggestions?</p>

<hr>

<h2>Consolidated List 66/75 Questions</h2>

<p>v/2L is fundamental frequency for string fastened at two ends
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
the merry go-around is spinning at the speed of 1/2 pi
75) B0 isnt necessary for emf (Confirmed)
the centripetal force decreased by a factor of 4 (F/4)
acceleration (mass?) of the pushed object is 5x 10^6
beta particle emission question: nuclear mass stays the same
the constant force applied on the 5 kg object was 30 N
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 (Confirmed)
two magnets are next to eachother:
–1st question: either one or both are permanent.
–2nd question: both are permanent (<strong>split)
RC Circuit - Q = cv = 20x10^6
change in kinetic energy of the object is F * d = 60 J
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 (Straight horizontal line) (Confirmed)
optics question with converging lens: same size, inverted
for 72) f/cos thetha
71) Force of friction with 100N force applied was F = 40 N
First few questions:
–1) momentum of II is greater
–2) momentum is ame
–3) momentum is same
optics question with plane mirror at an angle: image is virtual and not inverted (twist page and deal with it as a normal mirror question)
The resulting force of attraction between the two moved is 1 x 10^4 (originally 4e4)
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
80m for dropping something off a cliff
“II only” for the one with large and small boxes with temperature transfer (Confirmed)
For the 5 diagrams as choices with a satellite orbitting a planet. Mass and Radius varied.
–First problem, asked which had greatest 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
Waves interfere with each other and get diffracted at the two slits.
Switched I and III add up to the least resistance, thus the greatest current
Elevator problem: I only
Which of these could make the net force 0: I only
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 light radio) Answer: I, II, and III
Negatively charged rod and X and Y are ends of a piece of metal: Answer: voltage / net force = 0 (</strong>split)
Area under F vs t curve = impulse
Two different frequencies: beats (Confirmed)
Question underneath that: resonance (Confirmed)
Question underneath that: quality (Confirmed)
Center of mass of the frame: point D
Graph of ax + b is linear with a positive slope and y-intercept
The range of the perimeter of the rectangle where the sides were known to a ±.1 value was a range 13.6 to 14.4
A person throws an objects in the air, which graphs represents velocity v.s. time
–answ: the graph with the positive y-intercept that slopes down and intersects with x-axis
Which of the following stays constant for (object)?
–answ: acceleration
What is not true regarding the beta particle?
–answ: Minimum potential energy
A ruler attached to table undergoes simple harmonic motion
An atom emits a beta particle –> another particle must also be emitted
Acceleration of ball released from rest is same as ball thrown
Maximum current you could get from something with P=10 watts and a R= 20 ohms is 1/(sqrt2).
0 m/s velocity of block after collision
What causes thermometer to work - Mercury expands faster than glass.</p>

<p>

</p>

<p>I used the Princeton Review one, which is excellent. However, it seemed to go too much into detail with complicated formulas that rarely show up on the test, so I would just read it for main ideas and vocabulary.</p>

<p>for the mercury question: </p>

<p>“Bulb thermometers follow the simple principle that liquids change their volumes relative to their temperature. As temperatures rise, the mercury-filled bulb expands into the capillary tube. Its rate of expansion is calibrated on the glass scale”</p>

<p>it rises cuz the volume coefficient is high or sumthing like that</p>

<p>Mercury rises because its coefficient of volume expansion is higher than that of the glass. The change in volume is higher for mercury; hence, mercury rises in the thermometer when heated.</p>

<p>I am cautiously looking for an 800, because I missed 9; I confirmed 8 wrong questions and 1 omitted ones.</p>

<p>What is the general minimum raw score (approximately) out of 75 that would give one an 800 for this test?</p>

<p>

</p>

<p>Usually anything >60 is an 800, but >63 almost guarantees an 800.</p>

<p>Does anyone remember the question about the induced current in the loop, it was a I, II, and III question. Something like…
I.Placing a steady current next to the loop
II. Turning off the current
III. ??</p>

<p>I’m not sure what the 3rd one was, but I’m sure I chose an answer with 2 of them…</p>