HSC Physics Marathon 2013-2015 Archive (4 Viewers)

[omgiloverice]

re: HSC Physics Marathon Archive

(can someone check these pleass)
c) T=nbiAx1 (since parallel) = 250 x 5 x x3x0.15x0.3= 168.75 = 170Nm (1sf because only 1 in the question)

Incorrect, remember the definition of torque and then re-examine the graph.

 

[omgiloverice]

re: HSC Physics Marathon Archive

 

[yasminee96]

re: HSC Physics Marathon Archive

Lol, subbed numbers into calculator wrong. acceleration is -2.857 and max height 103.2. Is this right?

I got this too Is it right?

 

[Dementured]

re: HSC Physics Marathon Archive

I'm not sure how many marks this Q would be.. so i'll give it a shot.

Lenz's Law states that an induced emf will produce a magnetic field that opposes the original chance in magnetic flux. Without back emf, motors would not obey the law of conservation of energy, since if the induced emf did not oppose the change that produced it, an infinite energy supply would result. Hence, Lenz's Law is simply a consequence of energy conservation.

 

[yasminee96]

re: HSC Physics Marathon Archive

Incorrect, remember the definition of torque and then re-examine the graph.

Torque is the turning moment of a force...
I'm confused why is the answer provided incorrect D:

 

[omgiloverice]

re: HSC Physics Marathon Archive

Torque is the turning moment of a force...
I'm confused why is the answer provided incorrect D:

Torque can be also defined as the product of force and the perpendicular distance to the line of action of the force.
By looking at the diagram you only see one magnet on one side of the motor, therefore force is only acting on one side of the coil. Therefore you simply needed to divide by answer by two to find the torque.

 

[Fizzy_Cyst]

re: HSC Physics Marathon Archive

Lol, subbed numbers into calculator wrong. acceleration is -2.857 and max height 103.2. Is this right?

Yep

 

[Fizzy_Cyst]

re: HSC Physics Marathon Archive

Torque can be also defined as the product of force and the perpendicular distance to the line of action of the force.
By looking at the diagram you only see one magnet on one side of the motor, therefore force is only acting on one side of the coil. Therefore you simply needed to divide by answer by two to find the torque.

That is so evil.

That is something I would do.

 

[iBibah]

re: HSC Physics Marathon Archive

An electron jumps from the 3rd shell of a helium atom to the 1st shell. Find the wavelength of the emitted radiation.



lol

 

[Menomaths]

re: HSC Physics Marathon Archive

An electron jumps from the 3rd shell of a helium atom to the 1st shell. Find the wavelength of the emitted radiation.



lol

1.644x10^-26m?

What's the lol for? Trick question?

 

[AnimeX]

re: HSC Physics Marathon Archive

That's not 1 sf lol

oh my bad.... if they wanted 1SF and I had an answer of 168.75 would u actually put 200?

Incorrect, remember the definition of torque and then re-examine the graph.

hmm

An electron jumps from the 3rd shell of a helium atom to the 1st shell. Find the wavelength of the emitted radiation.



lol

is this in core modules?

 

[Menomaths]

re: HSC Physics Marathon Archive

oh my bad.... if they wanted 1SF and I had an answer of 168.75 would u actually put 200?


hmm

I doubt they would, but if they do then I would though.

 

[iBibah]

re: HSC Physics Marathon Archive

1.644x10^-26m?

What's the lol for? Trick question?

Rydbergs constant is for which atomic spectrum?

oh my bad.... if they wanted 1SF and I had an answer of 168.75 would u actually put 200?


hmm


is this in core modules?

nah its Q2Q

 

[Menomaths]

re: HSC Physics Marathon Archive

Rydbergs constant is for which atomic spectrum?





nah its Q2Q

I didn't use that though lol

 

[AnimeX]

re: HSC Physics Marathon Archive

Torque can be also defined as the product of force and the perpendicular distance to the line of action of the force.
By looking at the diagram you only see one magnet on one side of the motor, therefore force is only acting on one side of the coil. Therefore you simply needed to divide by answer by two to find the torque.

I still don't really get this, wouldn't the magnet also affect the other half of the coil?, if you think about it?
so I just needed to divide my answer by 2?

 

[Menomaths]

re: HSC Physics Marathon Archive

i did Ei-Ef

-13.6/9 + 13.6 = 12.088..
E=hf
12.088../6.626E-34 = f
c/f = wavelength = 1.64E-26 (which in this case is clearly =/= )

 

[iBibah]

re: HSC Physics Marathon Archive

i did Ei-Ef

-13.6/9 + 13.6 = 12.088..
E=hf
12.088../6.626E-34 = f
c/f = wavelength = 1.64E-26 (which in this case is clearly =/= )

Where is this from?

 

[Menomaths]

re: HSC Physics Marathon Archive

Where is this from?

I don't know...:/
Do I just do Ei-Ef = 1/n^2i - 1/n^2f ?

 

[Fizzy_Cyst]

re: HSC Physics Marathon Archive

Where is this from?

13.6 eV is ionisation energy of Hydrogen

That 12.xx answer Menomaths ends up with would be in eV, would have to convert to J before using E = hc/lambda

 

[iBibah]

re: HSC Physics Marathon Archive

13.6 eV is ionisation energy of Hydrogen

Exactly (thought you'd remember this trolling question lol)