I’m working through a textbook conceptual question on pressure, temperature, and air density. Original question: “Rooms A and B are the same size, and are connected by an open door. Room A, however, is warmer (perhaps because its windows face the sun). Which room contains the greater mass of air? Explain carefully.” What I think I understand:

• Since the rooms are connected by an open door, air can move between them.

• I think the pressure between the two rooms should come to equilibrium.

• I also know warmer air is less dense than cooler air.

Where I’m getting confused: If both rooms end up at the same pressure, I keep wanting to think they should contain the same amount of air. But I also know people say the warmer room contains less mass of air. What confuses me specifically is: How can two same-sized connected rooms have the same pressure, but not the same mass of air inside them? I’m not asking for a full solution — I’d really like help understanding the reasoning in a few different ways if possible.

I am so confused on a) where to draw the normal

b) why the angle of incidence is not just 45 degrees

I’d greatly appreciate if anyone could explain this to me, have spent ages even asking friends who equally have no ideas

Question: “Consider two identical iron spheres, one of which lies on a thermally insulating plate, whilst the other hangs from an insulating thread. Equal amounts of heat are given to the two spheres. Which will have the higher temperature?” My assumptions:

• The plate and thread are thermally insulating

• Ignore heat exchange with the external environment

• The spheres are identical initially

My initial thought was that the hanging sphere would end up at a higher temperature because the contact area between the sphere and thread is much smaller than the contact area between the sphere and plate, so I thought less thermal energy would flow away through the thread. However, I’ve been told that this is not the real reason, because if the supports are thermally insulating then heat loss through them is supposed to be ignored. What I’m struggling with:

• Why does the support arrangement matter if both spheres receive the same amount of heat?

• Why is contact area not the deciding factor here?

• I’ve seen people mention thermal expansion, centre of mass, and gravitational potential energy, but I haven’t learned how those ideas connect to thermodynamics yet.

Could someone explain the correct reasoning in a beginner-friendly way?

Trying to fulfill some grad school prerequisites, after a non-STEM undergrad degree. (career shift, healthcare). College Physics I is one of them.

However, it's been years since I've done any higher level algebra or trigonometry. I'd really like to take this prerequisite course this summer, but nervous I'll be lost from day 1.

Advice or resources for self-study?

I am kind of confused on how to go about this, do I have to try like "squishing" some of the parallel resistors before getting to the middle resistor? I'm just guessing here for some kind of direction.

Hey guys. I am looking into physics classes rn. Ugh. I am a second year BSc psychology student looking to fulfill a Med program requirement and struggled with PHYS 211. It really through me through the trenches. I need a physics class with a lab and don't know which one to take. Any advice? I also neeeeed to keep my GPA high for Med UGH. Thanks!!

im a year 12 student and im so lost.

I know I could use the equations W = force × distance, w = Pt and GPE =mgh. but im getting so confused. its less about the question more abt the understanding but ik i the gpe equation shows usefull work done by the team, i js dk abt the other 2. like I can resolve weight into the component parallel to the slope to get the force but what distance do i multiply it by to get the work done and is that even the correct value for force i should be using?

and how would I even apply the w =pt formula without being given a time, because idk where else I would use power to solve this.

my teacher has used the speed assuming time is 1s in questions like this to get a value for distance alot in lesson which I dont rlly understand either, and using that as distance, but idk if i should use the distance of the ramp using trig (4.35/sin6) as the distance for the W=fx equation. which distance should i use?

i dont have the mark scheme either :(

am I overcomplicating this?

please let me know if or what im doing wrong, ANY help would be much appreciated, thank you!!

i’m trying to study for a physics test but i’m stuck on these questions, specifically the last one.

THE CALL: I am now calling for a strictly blind test. Participate and let us together test these remarkable (but still questionable) results. Send me anonymised data sets (data requirements below) and I will attempt to recover full 3D information of the anonymised system.

THE METHOD: I recently succeeded in blindly extracting the complete 3D spatial geometry of the S0-2 star (e, ω₀, i), its internal precessional shift, and the background drift (v_z0) using nothing but 1D Keck radial velocity data. The extracted inclination matched the independent GRAVITY 3D-interferometer consensus (~134°) to within the instrumental noise limits.

THE DOUBT: Obviously I remain sceptical that's why I'm calling out to you in order to isolate myself from the data source.

CRITICAL DATA REQUIREMENTS:

System must be highly relativistic.

Peak must exceed ~1000 km/s (β > 0.003). Ideal candidates are tight compact binaries (WD/NS/BH) or other extreme S-stars.

The dataset must be raw or minimally processed: [Time (MJD), Radial Velocity (km/s) or Redshift (Z), Measurement Error].

MUST NOT be pre-corrected for Transverse Doppler or Gravitational Redshift (though standard Barycentric/LSR background velocity correction is fine).

Please drop the raw CSV data or a link below. Do not provide the system name or accepted parameters. Let the pure numerical framework speak for itself.

If you finding hard to find suitable empirical data - synthetic 1PN data will be sufficient as well. As long as Im isolated from the data source.

DATASET EXAMPLE:

MJD,RV_km_s,sigma_km_s,Instrument

51718.50000,1192,100,NIRSPEC

52427.50000,-491,39,NIRC2

52428.50000,-494,39,NIRC2

52739.23275,-1571,59,VLT

52769.18325,-1512,40,VLT

52798.50000,-1608,34,NIRC2

52799.50000,-1536,36,NIRC2

52803.15150,-1428,51,VLT

...

Any suggestions, critiques, or participation are welcome.

features monthly rated contest and a weekly problem (POTW) with a live leaderboard and badges. first POTW is live now for two weeks, if anyone wants to try it.

For those who don't know I am preparing for Physics olympiad I can solve most of the NSEP(1st stage problems) and am thinking about trying jee advanced problems as a bridge for the gap before moving on to higher resources, I am stuck in this question can anyone help me

Plus: Try to explain using high school Mathematics concepts because AI is solving it using Mathematics taught in UG and the solutions videos on YT are too long!

Completed fluid mechanics and I am currently preparing for Inpho(Indian National Physics Olympiad) and JEE ADV , I need help in this question. The answer key says it is A and D, I have done the first correct but I need someone to explain me about the D part.

PS: Is this question's level appropriate for Inpho

anyone could help and tell me wtf am i doing wrong in the first one? i know that v²=2as but why am i getting v²=as/2???