Physics - Got Some Questions (1 Viewer)

notme123

Well-Known Member
Joined
Apr 14, 2020
Messages
1,002
Gender
Male
HSC
2021
NSGHS has some really good questions in its maths exams so I am not surprised that the same is true of their physics exams. Definitely a source worth trying.
Confusingly, the NSBHS physics paper I actually thought was terrible, so I would assume the same from NSGHS, so it seems they're not under the same administrations.
 

CM_Tutor

Moderator
Moderator
Joined
Mar 11, 2004
Messages
2,644
Gender
Male
HSC
N/A
Confusingly, the NSBHS physics paper I actually thought was terrible, so I would assume the same from NSGHS, so it seems they're not under the same administrations.
I wondered whether to make any comment on NSBHS v NSGHS exams, but decided not to, but since you have brought it up...

I have looked at a lot of exam papers (though not physics) and consider NSGHS papers to be likely sources for original / challenging questions. NSBHS exams much more frequently have borrowed questions or questions obviously from organisations that sell papers. NSBHS exams also vary in quality between years, presumably reflecting different writers.

Both schools are academically selective and have some very very talented students, but I think NSGHS is the stronger school... and they are most definitely run separately.
 

Life'sHard

Well-Known Member
Joined
May 24, 2021
Messages
1,102
Gender
Male
HSC
2021
Uni Grad
2025
Pre sure it's

Q1)d - solenoid rule and then force on each side

Q2)b - look at difference in mass 2.5g is divisible by all of them

Q3)c - lcm
For Q1, I'm a little laggy havent done phys in a while, how do you determine force when the N and S poles arent given? Also what's Icm?
 

vishnay

God
Joined
Sep 6, 2020
Messages
905
Gender
Male
HSC
2021
For Q1, I'm a little laggy havent done phys in a while, how do you determine force when the N and S poles arent given? Alos what is Icm?
Use the right hand solenoid rule on both sides to determine the poles

and lcm = lowest common multiple
 

Life'sHard

Well-Known Member
Joined
May 24, 2021
Messages
1,102
Gender
Male
HSC
2021
Uni Grad
2025
Use the right hand solenoid rule on both sides to determine the poles

and lcm = lowest common multiple
Hmm is the direction of grip the direction of rotation? Where the thumb is the direction of current.
 

Life'sHard

Well-Known Member
Joined
May 24, 2021
Messages
1,102
Gender
Male
HSC
2021
Uni Grad
2025
fingers are current and thumb points toward north pole
I'm cooked man what? I can't seem to use the rule in relation to the the flow of current for the diagram. How would your curled fingers mimic the direction of flow in the motor?

q1 is a decent q. where r u getting this from?
Sydney Boys
 

vishnay

God
Joined
Sep 6, 2020
Messages
905
Gender
Male
HSC
2021
I'm cooked man what? I can't seem to use the rule in relation to the the flow of current for the diagram. How would your curled fingers mimic the direction of flow in the motor?


Sydney Boys
curl ur fingers in direction of current

follow along the coil for both lhs and rhs and thumb points to north pole
schoolphysics ::Welcome::
 

idkkdi

Well-Known Member
Joined
Aug 2, 2019
Messages
2,454
Gender
Male
HSC
2021
I'm cooked man what? I can't seem to use the rule in relation to the the flow of current for the diagram. How would your curled fingers mimic the direction of flow in the motor?


Sydney Boys
don't use it on the actual DC motor coil (drawn in bold).

Solenoid rule on the electromagnets. Draw the poles. You get the magnetic field. This is B
This magnetic field then influences the current on the DC motor coil. This part is qv.

Then right hand rule F=qvB, t=rF for torque and hence the rotation direction.
 

notme123

Well-Known Member
Joined
Apr 14, 2020
Messages
1,002
Gender
Male
HSC
2021
the last one isnt a physics q in my opinion its more mathsy because it has to do with multiples and circles and crap. Theres nothing physics about it.
 

Life'sHard

Well-Known Member
Joined
May 24, 2021
Messages
1,102
Gender
Male
HSC
2021
Uni Grad
2025
don't use it on the actual DC motor coil (drawn in bold).

Solenoid rule on the electromagnets. Draw the poles. You get the magnetic field. This is B
This magnetic field then influences the current on the DC motor coil. This part is qv.

Then right hand rule F=qvB, t=rF for torque and hence the rotation direction.
curl ur fingers in direction of current

follow along the coil for both lhs and rhs and thumb points to north pole
View attachment 31963
Mega brain moment holy shit I think I got it.
This vid was kinda nice if you just want a little refresher. So basically you simplify everything so that it's just a positive flowing to the negative terminal. The motor part is basically just the solenoid, correct me if I'm incorrect.
 

idkkdi

Well-Known Member
Joined
Aug 2, 2019
Messages
2,454
Gender
Male
HSC
2021
Mega brain moment holy shit I think I got it.
This vid was kinda nice if you just want a little refresher. So basically you simplify everything so that it's just a positive flowing to the negative terminal. The motor part is basically just the solenoid, correct me if I'm incorrect.
1630939744002.png
these are what vishay was referring to as solenoids.
 

Life'sHard

Well-Known Member
Joined
May 24, 2021
Messages
1,102
Gender
Male
HSC
2021
Uni Grad
2025
View attachment 31964
these are what vishay was referring to as solenoids.
Doesn’t conventional current always flow from positive to negative? Therefore the negative terminal should always be the North (like a solenoid where entry is pos and exit is neg terminal where thumb is at the exiting end)? My question now is what distinguishes C from D and why?

 

notme123

Well-Known Member
Joined
Apr 14, 2020
Messages
1,002
Gender
Male
HSC
2021
Doesn’t conventional current always flow from positive to negative? Therefore the negative terminal should always be the North (like a solenoid where entry is pos and exit is neg terminal where thumb is at the exiting end)? My question now is what distinguishes C from D and why?
It's because the negative solenoid in C is actually in the opposite direction to the other solenoid so they don't create a continuous uniform/radial field i think. So the forces on each coil edge is canceled out.
 

Life'sHard

Well-Known Member
Joined
May 24, 2021
Messages
1,102
Gender
Male
HSC
2021
Uni Grad
2025
Q
Screen Shot 2021-09-07 at 12.53.42 pm.png

Need some reasoning. I don't see how the voltage should appear constant in X when the switch is turned off.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top