Physics - Got Some Questions (2 Viewers)

[Life'sHard]

All of those questions are from the North Sydney Girls High School 2020 Physics Trial Examination.

Thanks for the clarification

 

[notme123]

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]

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]

1)


2)


3)


Need help.

 

[vishnay]

1)
View attachment 31957

2)
View attachment 31958

3)
View attachment 31959

Need help.

Pre sure it's

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

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

Q3)c - lcm

 

[Life'sHard]

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]

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]

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.

 

[vishnay]

Hmm is the direction of grip the direction of rotation? Where the thumb is the direction of current.

fingers are current and thumb points toward north pole

 

[idkkdi]

1)
View attachment 31957

2)
View attachment 31958

3)
View attachment 31959

Need help.

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

 

[Life'sHard]

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]

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

pre sure q1 is hsc

nvm

 

[vishnay]

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

 

[idkkdi]

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]

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]

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]

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.

these are what vishay was referring to as solenoids.

 

[Life'sHard]

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?

Google Image Result for https://stickmanphysics.com/wp-content/uploads/2020/02/Electromagnet-Clockwise-Hand.gif

 

[notme123]

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]

Q


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