oceanangel

Oh that was stopwatch to measure period

ns614

oh right..haha i was thinking about torque or something. and what was the answer to the the graph with the P, V, and T? Where is the change in internal energy 0?

oceanangel

Oh yeah I forgot if change in internal energy equals temperature or heat transferred.. I assumed it was isothermic and picked D or something, along the lower dotted line. If it were adiabatic it's E.. I'm not sure.. We are actually learning this in ap physics now haha should have paid more attention

There was one question with five chrges in a circle in a magnetic field made of parallel wires. Which one experienced the greatest force? Was it E?

collegeuser

throw a ball 6 times higher on the moon? orbit 3R from earth has 1/9g?
pulley system- greater M is closer to the ground?
4eV for minimum energy needed?

oceanangel

I skipped the moon one
1/9g
Pulley- both the same mass
I guessed A for the minimum energy one which was 5 something.. That's wrong tho I think

basketball1

i think the magnetic force made of parallel wires was C actually. This is because if you look at the equation e=vbl, the velocity and magnetic field were constant. Therefore only length matters and C had the greatest length.

oceanangel

Weren't all the wired the same length? It's just that the charges are traveling in different directions.

basketball1

and what was the answer to the idea similar to a rocket launched?

basketball1

right but C was the furthest on the top and therefore it had the greatest amount of wire below it

oceanangel

Oh I didn't know it depended on the amount of wire BELOW... Why is that..?
Btw I put A for the rocket one, pushing a boat away from shore with oar

basketball1

yeah i put A too for that, and i don't really feel comfortable with my reasoning either, but if the velocity and magnetic field were all constant, what would differentiate the points? It was to be some kind of length. What else could it be?

Josmur

For the rocket propulsion one it's throwing rocks off of the boat. It's akin to the burning and expelling of fuel propelling the rocket.

nick321

Moon: conservation of energy gives mgh = .5mv^2 <=> gh = .5v^2, right term is constant, g is six times smaller => h six time larger.
Orbit: f = g m1m2 / r^2 so if r1^2 = 1 and r2^2 = 9 then f2 = f1 / 9.
Pulley: same force => same mass
Minimum energy: E = fh = (c / l)h =~ 4 eV
Magnetic field with two wires: B = something I / r = constant, I two times larger => r two times larger.
Rocket: a rocket propels by 'throwing' away hot masses.
Wires in a field: The force is the cross product of the movement vector (tangent to the circle) and the field lines. Zero when parallel, maximum when perpendicular.

Not too sure about these:
Graph with pressure / volume: Internal energy = temperature?

oceanangel

oh I put charge E cuz it was traveling at ninety degrees to the magnetic field.. Guessed haha

oceanangel

Btw I just looked up rocket propulsion, it said it uses mainly newtons third law, which means the answer is A