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HSC Physics Marathon 2013-2015 Archive (3 Viewers)
- Thread starter Magical Kebab
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Fizzy_Cyst
Well-Known Member
re: HSC Physics Marathon Archive
Correct working, but I end up with a value of 6390km?
New Question:
Determine the work required to accelerate an electron from rest to 0.98c (3 marks)
Correct working, but I end up with a value of 6390km?
New Question:
Determine the work required to accelerate an electron from rest to 0.98c (3 marks)
Fizzy_Cyst
Well-Known Member
re: HSC Physics Marathon Archive
I think you forgot to halve it
But correct process
Here is one my tutor students struggled with in their examination
New Question: (There was a diagram to go with it, but it makes sense without it)
Two clocks are started simultaneously.
A rocketship instantaneously accelerates to 0.6c as the clocks are started.
At the instant in time that the observer on the ground measures the rocketship to have travelled 5.4x10^10m, how much time has the observer in the rocketship seen elapse on the clock on the ground?
I think you forgot to halve it
But correct process
Here is one my tutor students struggled with in their examination
New Question: (There was a diagram to go with it, but it makes sense without it)
Two clocks are started simultaneously.
A rocketship instantaneously accelerates to 0.6c as the clocks are started.
At the instant in time that the observer on the ground measures the rocketship to have travelled 5.4x10^10m, how much time has the observer in the rocketship seen elapse on the clock on the ground?
Fizzy_Cyst
Well-Known Member
re: HSC Physics Marathon Archive
That's not the answer, but it is part way there
That's not the answer, but it is part way there
colinrocks95
New Member
- Joined
- Mar 23, 2012
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- Male
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- 2012
re: HSC Physics Marathon Archive
My question is:
Planet A has half the radius of planet B. Both planets have different masses. What is the ratio of their masses if the speed of an object orbiting planet A, at an orbital radius equal to the radius of planet B, is equal to the minimum speed required to launch the object from the surface of planet B?
By the way, I got good at maths and physics from the HSC programs at Sci School. The presenter is funny and explains things really well. You should check them out.
Since each moon orbits the same planet, M_planet is the same for each of them. Orbital velocity is independent of the mass of the orbiting object. Since each moon has the same orbital velocity, they all have THE SAME ORBITAL RADII, i.e. the ratio is 1:1:1. This is because Kepler's formula (on the data sheet) is r^3/T^2 = G*M_planet / 4*pi^2. Note: equal orbital velocities mean equal orbital periods (T), which is the time it takes for one complete orbit.
My question is:
Planet A has half the radius of planet B. Both planets have different masses. What is the ratio of their masses if the speed of an object orbiting planet A, at an orbital radius equal to the radius of planet B, is equal to the minimum speed required to launch the object from the surface of planet B?
By the way, I got good at maths and physics from the HSC programs at Sci School. The presenter is funny and explains things really well. You should check them out.
re: HSC Physics Marathon Archive
Let
and 
.
When the observer on the ground measures the spaceship to have travelled the distance
, the time elapsed on his/her ground clock is
.
Therefore, the time that the ground observer sees elapsed on the spaceship clock at this instant is
}}=\frac{D}{V}\cdot \sqrt{1-\frac{V^2}{c^2}})
.
When the spaceship observer sees his/her spaceship clock have this time of elapsed, he/she sees the ground clock have the following time elapsed:
}}=\frac{D}{V}\cdot \sqrt{1-\frac{V^2}{c^2}}\cdot\sqrt{1-\frac{V^2}{c^2}}=\frac{D}{V}\cdot \left ( 1-\frac{V^2}{c^2} \right ))
.
Now, plugging in the values given in the question, the answer is
}}=\frac{D}{V}\cdot \left ( 1-\frac{V^2}{c^2} \right ))
^2\right ))
.
I think you forgot to halve it
But correct process
Here is one my tutor students struggled with in their examination
New Question: (There was a diagram to go with it, but it makes sense without it)
Two clocks are started simultaneously.
A rocketship instantaneously accelerates to 0.6c as the clocks are started.
At the instant in time that the observer on the ground measures the rocketship to have travelled 5.4x10^10m, how much time has the observer in the rocketship seen elapse on the clock on the ground?
Let
When the observer on the ground measures the spaceship to have travelled the distance
Therefore, the time that the ground observer sees elapsed on the spaceship clock at this instant is
When the spaceship observer sees his/her spaceship clock have this time of
Now, plugging in the values given in the question, the answer is
astroman
Well-Known Member
Kaido
be.
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- Jul 7, 2014
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- Male
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- 2015
re: HSC Physics Marathon Archive
what topic is that under? (dont remember being in the core)
astroman
Well-Known Member
astroman
Well-Known Member
re: HSC Physics Marathon Archive
q2q is useful for most uni physics, astro isn't really.ohh i see, astrophysics seems interesting, but Q2Q still the boss
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