HSC Physics Marathon 2016 (3 Viewers)

[DatAtarLyfe]

I know. I may include a diagram of the apparatus later and attempt a rewording.

M9, you never did

 

[Nailgun]

A student sets up the following apparatus.

Two wires are connected to a power box (6V) on one end, and a strip of aluminium foil (resistance = 1Ω) on the other. The aluminium fold bends on top of itself in this circuit. (Picture a C shape the foil is making.)

When the switch was turned on, momentarily the aluminium foil appeared to expand.

a) What happened to the power box once the switch got flicked and why? (2)
b) Carefully explain (with or without use of a diagram) why the aluminium foil expanded. (4)
c) The average seperation distance of the foil was 3mm. Calculate the force each side of the foil exerted on each other. (3)

Still trying to understand what these mean lol

 

[leehuan]

M9, you never did

I got lazy. I'll do one today lol.

 

[DatAtarLyfe]

I got lazy. I'll do one today lol.

Well can you post another qu. we can do whilst you work that out?

 

[leehuan]

And if you're still having trouble the foil looks like this

TBH - Does it matter? NO. It just had to be a thin sheet of electroconductive material.

Sent from my iPhone using Tapatalk

 

[leehuan]

So when I say expanded, you can picture it as though the ends suddenly bloated out. Which is kinda what image 2 looks like tbh

 

[Drsoccerball]

1) Set up to parallel retort stands (separated slightly) with magnets attached to each with opposite polarities.
2) Connect either aluminium foil or a wire to an external circuit of 4-6 V and place inside the magnetic field observing the effects.
3) Vary the magnetic field strength by adding more magnets/stronger magnets, increase voltage, increase length, change direction of polarities and also observe effects.
4) It is seen to follow the right hand palm rule and thus also through the relative movement demonstrates the motor effect.

 

[Nailgun]

A student sets up the following apparatus.

Two wires are connected to a power box (6V) on one end, and a strip of aluminium foil (resistance = 1Ω) on the other. The aluminium fold bends on top of itself in this circuit. (Picture a C shape the foil is making.)

When the switch was turned on, momentarily the aluminium foil appeared to expand.

a) What happened to the power box once the switch got flicked and why? (2)
b) Carefully explain (with or without use of a diagram) why the aluminium foil expanded. (4)
c) The average seperation distance of the foil was 3mm. Calculate the force each side of the foil exerted on each other. (3)

a) I'm a bit confused to as what you mean lol but I'll try. As the current from the power source does not automatically go to maximum and requires a momentary build-up time, the reading on the voltmeter (power box?) will similarly increase as V is proportional to I (shown in V = IR, where R is a constant in this case). That is, as I increases to a maximum, V also increases to a maximum.

b) Parallel current carrying conductors produce a force which depending on the direction of each current will either repel the two conductors from each other or attract them. This relationship is shown in the equation F/l = k.I1.I2/d. In this case, as the currents are in opposite directions, a force of repulsion will act on them, causing the loop of aluminium foil to 'expand' as the sides are forces away from each other. This force is produced as a result of the motor effect, where the interaction of each side of the loops magnetic field interacts with the other, causing a force to be produced. This can be modeled with the right hand grip and right hand palm rules demonstrating the repulsive force. The expansion is only momentary as according to the formula F/l = k.I1.I2/d, the force is inversely proportional to distance, and as the coil expands, the system reaches equilibrium as the force becomes negligible.

c) idk how to calculate this without the length of at least one side of the aluminium. But V = IR hence I = 6A, therefore F = l.k.I1.I2/d
F = 2.4 x 10^(-3) x length away from each other side of the aluminium loop

 

[leehuan]

a) I'm a bit confused to as what you mean lol but I'll try. As the current from the power source does not automatically go to maximum and requires a momentary build-up time, the reading on the voltmeter (power box?) will similarly increase as V is proportional to I (shown in V = IR, where R is a constant in this case). That is, as I increases to a maximum, V also increases to a maximum.

b) Parallel current carrying conductors produce a force which depending on the direction of each current will either repel the two conductors from each other or attract them. This relationship is shown in the equation F/l = k.I1.I2/d. In this case, as the currents are in opposite directions, a force of repulsion will act on them, causing the loop of aluminium foil to 'expand' as the sides are forces away from each other. This force is produced as a result of the motor effect, where the interaction of each side of the loops magnetic field interacts with the other, causing a force to be produced. This can be modeled with the right hand grip and right hand palm rules demonstrating the repulsive force. The expansion is only momentary as according to the formula F/l = k.I1.I2/d, the force is inversely proportional to distance, and as the coil expands, the system reaches equilibrium as the force becomes negligible.

c) idk how to calculate this without the length of at least one side of the aluminium. But V = IR hence I = 6A, therefore F = l.k.I1.I2/d
F = 2.4 x 10^(-3) x length away from each other side of the aluminium loop

My bad on c), was meant to say force per metre. That aside since you didn't directly show your substitution given what you had I will only assume you're right. Also, units, Newtons.

a) - That was testing your skills. That is a short circuit right there so the overload on the powerbox will, in a matter of milliseconds, be flicked off.

b) was well done

 

[Nailgun]

My bad on c), was meant to say force per metre. That aside since you didn't directly show your substitution given what you had I will only assume you're right. Also, units, Newtons.

yeah i would set it out properly if i was using latex or writing it lol but i ceebsed

a) - That was testing your skills. That is a short circuit right there so the overload on the powerbox will, in a matter of milliseconds, be flicked off.

ah crap, thats so obvious lol. aluminium would melt yeah

b) was well done

ty

 

[leehuan]

NEXT QUESTION:

a) Outline Galileo's analysis of projectile motion. (3 mks)
b) An astronaut on the Moon throws a stone from a 150m high cliff. The stone hits the ground a distance of 300m away, 21.0s later. If gravitational acceleration is equal to 1.6ms^-2 on the Moon, determine the initial velocity which the stone was projected from. (5 mks)
c) Suppose the exact same scenario was replicated, except on Earth. Identify two differences between the motion of the stone on both planets. (2 mks)

 

[Nailgun]

NEXT QUESTION:

a) Outline Galileo's analysis of projectile motion. (3 mks)
b) An astronaut on the Moon throws a stone from a 150m high cliff. The stone hits the ground a distance of 300m away, 21.0s later. If gravitational acceleration is equal to 1.6ms^-2 on the Moon, determine the initial velocity which the stone was projected from. (5 mks)
c) Suppose the exact same scenario was replicated, except on Earth. Identify two differences between the motion of the stone on both planets. (2 mks)

lol hsc question

 

[leehuan]

lol hsc question

I tweaked b) a bit.

Basically you aren't guided as to how to do the q this time lol

 

[Nailgun]

NEXT QUESTION:

a) Outline Galileo's analysis of projectile motion. (3 mks)
b) An astronaut on the Moon throws a stone from a 150m high cliff. The stone hits the ground a distance of 300m away, 21.0s later. If gravitational acceleration is equal to 1.6ms^-2 on the Moon, determine the initial velocity which the stone was projected from. (5 mks)
c) Suppose the exact same scenario was replicated, except on Earth. Identify two differences between the motion of the stone on both planets. (2 mks)

a) Galileo was the first person to mathematically analyse projectile motion and separate it into x
and y components. The main problem with previous analysis of the motion had to do with the
objects moving too fast for accurate measurement and the presence of air resistance. However through
experimentation with ball-bearings and inclined planes Galileo was able to conclude that projectile
motion was made up of two separate components – a constant horizontal motion with zero
acceleration and an accelerating vertical motion with a uniform acceleration (gravity). He also
realized that motion of projectiles has a parabolic trajectory due to the proportionality of the
constant x component and the uniform acceleration of the y component.

b)


c) The maximum height would be lower, The range would be lower

spend like 3x more time writing up the tex than i did doing all three questions combined

 

[leehuan]

a) Galileo was the first person to mathematically analyse projectile motion and separate it into x
and y components. The main problem with previous analysis of the motion had to do with the
objects moving too fast for accurate measurement and the presence of air resistance. However through
experimentation with ball-bearings and inclined planes Galileo was able to conclude that projectile
motion was made up of two separate components – a constant horizontal motion with zero
acceleration and an accelerating vertical motion with a uniform acceleration (gravity). He also
realized that motion of projectiles has a parabolic trajectory due to the proportionality of the
constant x component and the uniform acceleration of the y component.

b)


c) The maximum height would be lower, The range would be lower

spend like 3x more time writing up the tex than i did doing all three questions combined

Lol just use daum like I do.

For a) you should always mention that this is true if and only if air resistance can be ignored.

b) Should've given answer to 2 sig fig; least amount of sig figs in question

Other than that beautiful

 

[Nailgun]

Lol just use daum like I do.

For a) you should always mention that this is true if and only if air resistance can be ignored.

b) Should've given answer to 2 sig fig; least amount of sig figs in question

Other than that beautiful

I do use daum lol, thats why it takes so long

a) ah true lol
b) yeah probs lol; although i heard that in physics they don't really care? still should though

 

[leehuan]

True, but unless you're InteGrand or someone it's faster than actually typing the LaTeX

Depends on who marks your question. Some examiners get fussy others don't. That's why it depends on a chance you can't risk

 

[RachelGreen]

Explain how the results of the Michelson and Morley's experiment can be used to support Einstein's assertion that the speed of light is constant. [3]

 

[porcupinetree]

True, but unless you're InteGrand or someone it's faster than actually typing the LaTeX

Depends on who marks your question. Some examiners get fussy others don't. That's why it depends on a chance you can't risk

I'd agree with this - you might as well get into the habit of writing the correct number of significant figures.

 

[Bestintheworld]

fking right hand rule is pissing the shit out of me.


Ps. sorry for derailing the thread