HSC Physics Marathon 2013-2015 Archive (6 Viewers)

abdog · Oct 30, 2013

re: HSC Physics Marathon Archive

A man throws a rock vertically and it reaches a height of 20m. Acceleration due to gravity on the moon is 1.6ms-2. What is the speed at which it was thrown on the moon?

Deliriously · Oct 30, 2013

re: HSC Physics Marathon Archive

abdog said:
A man throws a rock vertically and it reaches a height of 20m. Acceleration due to gravity on the moon is 1.6ms-2. What is the speed at which it was thrown on the moon?

Applying v2 = u2 +2as for y component
u2 = 2(1.6)(20)
u = 8ms^-1

Q: Two satellites X and Y orbit the Earth. The mass of satellite X is twice that of satellite Y. The orbital radius of satellite Y is twice that of satellite X. What is the ratio of the orbital speed of satellite X to the orbital speed of satellite Y. (Was from my trial paper but I don't know where they took it from)

JonskiG · Oct 30, 2013

re: HSC Physics Marathon Archive

Q: Two satellites X and Y orbit the Earth. The mass of satellite X is twice that of satellite Y. The orbital radius of satellite Y is twice that of satellite X. What is the ratio of the orbital speed of satellite X to the orbital speed of satellite Y. (Was from my trial paper but I don't know where they took it from)

y = sqrt(GM/2r) x=sqrt(G2M/r)

y:x
1:4

Q: With reference to the photoelectric effect, and pn-junction, explain the operation of a solar cell (4 Marks)

Deliriously · Oct 30, 2013

re: HSC Physics Marathon Archive

JonskiG said:
y = sqrt(GM/2r) x=sqrt(G2M/r)

y:x
1:4

Hmm that question was actually an MCQ but X:Y 4:1 wasn't one of the options.

They were:
A) 1:1
B) 1: sqrt(2)
C) sqrt(2):1
D) 2:1

Menomaths · Oct 30, 2013

re: HSC Physics Marathon Archive

Deliriously said:
Hmm that question was actually an MCQ but X:Y 4:1 wasn't one of the options.

They were:
A) 1:1
B) 1: sqrt(2)
C) sqrt(2):1
D) 2:1

Where'd you get this question from? It was in my trials.

hayabusaboston · Oct 30, 2013

re: HSC Physics Marathon Archive

SuperSAIyan, r u sum prodigy? lol

Deliriously · Oct 30, 2013

re: HSC Physics Marathon Archive

Menomaths said:
Where'd you get this question from? It was in my trials.

My trial as well. haha

Menomaths · Oct 30, 2013

re: HSC Physics Marathon Archive

Deliriously said:
My trial as well. haha

Answer is C

Deliriously · Oct 30, 2013

re: HSC Physics Marathon Archive

Menomaths said:
Answer is C

Yups. Reason why i posted was i got tricked. Orbital velocity doesn't depend on mass of the object orbiting T_T

hit patel · Oct 30, 2013

re: HSC Physics Marathon Archive

Good Luck guys. Hope you guys 'kill' the test and give it in 1 piece.

superSAIyan2 · Oct 30, 2013

re: HSC Physics Marathon Archive

identify three properties of superconductors

ColdLipstick · Oct 31, 2013

re: HSC Physics Marathon Archive

superSAIyan2 said:
identify three properties of superconductors

- They have no resistance when passed beyond the critical temperature.
- They can expel external magnetic fields.
- Can carry large currents without heat loss.

Outline the roles of the deflection plates and electrodes in an electron gun. (2 marks)

Fizzy_Cyst · Oct 31, 2013

re: HSC Physics Marathon Archive

superSAIyan2 said:
i wont post my working yet. But is the answer: acceleration is -4.8m/s/s and max height 173.4m

With these numbers Uy = 40.8 and after 3s, the delta Y is 100m, not 60m!

superSAIyan2 · Oct 31, 2013

re: HSC Physics Marathon Archive

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

omgiloverice · Oct 31, 2013

re: HSC Physics Marathon Archive

$$During a study of a certain planet, it was noted that the mass of the planet was $2.5$ times greater then Jupiter, and it's radius was 1.5 times greater than Jupiter as well. \\ If the acceleration due to gravity on Jupiter was $25.8 \ m.s^{-2}$ find the acceleration due to gravity of the certain planet.$

$$Describe the Michelson-Morley attempt to measure the relative velocity of the earth through the aether, and discuss how the 'negative' result gave rise to new theories on the nature of light.$

In the diagram above, a DC motor contains a rectangular coil consisting of 250 turns and with a width of 15 cm and a length of 30 cm within an 5 T magnetic field. If the coil is parallel to the rectangular magnet and carrying a current of 3A. Calculate the torque experienced by the coil.

Dementured · Oct 31, 2013

re: HSC Physics Marathon Archive

ColdLipstick said:
- They have no resistance when passed beyond the critical temperature.
- They can expel external magnetic fields.
- Can carry large currents without heat loss.

Outline the roles of the deflection plates and electrodes in an electron gun. (2 marks)

The cathode is heated and produces electrons.
The anode attracts the electrons, accelerating and focusing them.
The deflection plates bend the beam towards a fluorescent screen to produce a picture.

AnimeX · Oct 31, 2013

re: HSC Physics Marathon Archive

omgiloverice said:
$$During a study of a certain planet, it was noted that the mass of the planet was $2.5$ times greater then Jupiter, and it's radius was 1.5 times greater than Jupiter as well. \\ If the acceleration due to gravity on Jupiter was $25.8 \ m.s^{-2}$ find the acceleration due to gravity of the certain planet.$

$$Describe the Michelson-Morley attempt to measure the relative velocity of the earth through the aether, and discuss how the 'negative' result gave rise to new theories on the nature of light.$

In the diagram above, a DC motor contains a rectangular coil consisting of 250 turns and with a width of 15 cm and a length of 30 cm within an 5 T magnetic field. If the coil is parallel to the rectangular magnet and carrying a current of 3A. Calculate the torque experienced by the coil.

(can someone check these pleass)
a) g planet = 10/9 x 25.8 = 28.67ms^-2 = 29ms^-2 (2 sf)

b) The michelson and morley experiment involved shining a monochormatic light onto a tilted half silvered mirror which redirected the light perpendicular to each other, the light reflected off two mirrors and continued to hit the half silvered mirror again, then finally the two seperate lights travelled to the detector. The apparatus was rotated 90 degree and this experiment was repeated. There was a null result. The negative result of the Michelson Morley experiment gave rise to Einstein's theory of special relativity, although the aether model was superflous in his explanation, the negative result innovated him to study the nature of light.

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

AnimeX · Oct 31, 2013

re: HSC Physics Marathon Archive

1) Outline the basis of the slingshot effect and how it is used to conserve fuel on trips to outer space.

2) i) Outline newton's concept of escape velocity and calculate the escape velocity for Earth.
ii) If possible, would an object launched at 12000ms^2 from the ground escape the earth

3) Outline the steps of getting power from the power station to its point of use, comment on why high voltages are used at certain stages.

hayabusaboston · Oct 31, 2013

re: HSC Physics Marathon Archive

Is it weird that I feel like I cbf doing these questions, I just want to get exam over and done with already and not have to spend more time agonising over whether I know everything?

Cos Ive covered whole syllabus, feeling quite content, and feel sad when I think about doing more physics than necessary LOL

Menomaths · Oct 31, 2013

re: HSC Physics Marathon Archive

AnimeX said:
c) T=nbiAx1 (since parallel) = 250 x 5 x x3x0.15x0.3= 168.75 = 170Nm (1sf because only 1 in the question)

That's not 1 sf lol

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