HSC Physics Marathon 2013-2015 Archive (1 Viewer)

Status
Not open for further replies.

Kaido

be.
Joined
Jul 7, 2014
Messages
823
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

Uhh, a) planet B
B) 5.957 x10^24 N

Just guessing , haven't done this in ages lol
 
Last edited:

anomalousdecay

Premium Member
Joined
Jan 26, 2013
Messages
5,769
Gender
Male
HSC
2013
re: HSC Physics Marathon Archive

Uhh, a) planet B
B) 8.936 x10^35 N

Just guessing , haven't done this in ages lol
I got something a bit different actually (2.8227 E 24) but not sure though as I could have made a mistake somewhere.

But yeah post up another question.
 

Kaido

be.
Joined
Jul 7, 2014
Messages
823
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

Anyone got good questions? Thread seems dead...
 

duhdevitt

Active Member
Joined
Oct 6, 2014
Messages
191
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

I'll be posting some tomorrow cos I've been heaps busy with assesments


rexona <3
 

C20H25N3O

Member
Joined
Nov 24, 2014
Messages
71
Location
Apathetic
Gender
Undisclosed
HSC
2015
re: HSC Physics Marathon Archive

A basketball initially at rest is dropped from a height, collides with the ground and bounces back up. Assuming the collision is elastic, sketch graphs of acceleration over time, velocity over time for 2 bounces on different sets of axis.
 

duhdevitt

Active Member
Joined
Oct 6, 2014
Messages
191
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

ok guys, tomorrow onwards let's get this thing back on track. Get ready for some questions
 

Fizzy_Cyst

Well-Known Member
Joined
Jan 14, 2011
Messages
1,189
Location
Parramatta, NSW
Gender
Male
HSC
2001
Uni Grad
2005
re: HSC Physics Marathon Archive

Person A and Person B both fly to a planet which is 25 light years away.

Person B flies at 0.8c and Person B flies at 0.6c.

When both people arrive, who is older and by how much?
 

Rhinoz8142

Well-Known Member
Joined
Jul 25, 2013
Messages
1,342
Location
Sydney
Gender
Male
HSC
2014
Uni Grad
2018
re: HSC Physics Marathon Archive

Person A and Person B both fly to a planet which is 25 light years away.

Person B flies at 0.8c and Person B flies at 0.6c.

When both people arrive, who is older and by how much?
Find the time dilation

The one with the highest dilation is the oldest

Subtract with result of time dilation thus providing the difference


Is this right ?

Sorry , I am out right now... Don't have calculator
 

beaubrah

Member
Joined
Jan 25, 2014
Messages
109
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

Find the time dilation

The one with the highest dilation is the oldest

Subtract with result of time dilation thus providing the difference


Is this right ?

Sorry , I am out right now... Don't have calculator
That seems correct I think
 

Fizzy_Cyst

Well-Known Member
Joined
Jan 14, 2011
Messages
1,189
Location
Parramatta, NSW
Gender
Male
HSC
2001
Uni Grad
2005
re: HSC Physics Marathon Archive

Find the time dilation

The one with the highest dilation is the oldest

Subtract with result of time dilation thus providing the difference


Is this right ?

Sorry , I am out right now... Don't have calculator
Not that simple.

:)

Show me the working!!
 

PhysicsMaths

Active Member
Joined
Dec 9, 2014
Messages
179
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

Person A and Person B both fly to a planet which is 25 light years away.

Person B flies at 0.8c and Person B flies at 0.6c.

When both people arrive, who is older and by how much?
Hmm.. not too sure, but:
For person A, it would take 25/0.8 = 31.25 years
For person B, it would take 25/0.6 = 41.67 years

But time also dilates so...
using tv = t0 / √(1-v^2/c^2)

For A, 25√ (1-(0.8)^2 = 15 years
For B, 25√ (1-(0.6)^2 = 20 years

Difference = (41.67-31.25)-(20-15)
= 5.42 years -> Person B will be 5.42 years older than person A
 

Fizzy_Cyst

Well-Known Member
Joined
Jan 14, 2011
Messages
1,189
Location
Parramatta, NSW
Gender
Male
HSC
2001
Uni Grad
2005
re: HSC Physics Marathon Archive

Right approach, finding both proper time and dilated time, but you have made a boo boo with the t0 when calculating dilated time :)

btw, strong first post! :)

According to what you have done, A should age ~27 years, but B only ages 20 years. The person who travels faster will always age less
 

PhysicsMaths

Active Member
Joined
Dec 9, 2014
Messages
179
Gender
Male
HSC
2015
re: HSC Physics Marathon Archive

Right approach, finding both proper time and dilated time, but you have made a boo boo with the t0 when calculating dilated time :)

btw, strong first post! :)

According to what you have done, A should age ~27 years, but B only ages 20 years. The person who travels faster will always age less
For person A, it would take 25/0.8 = 31.25 years
For person B, it would take 25/0.6 = 41.67 years

But time also dilates so...
using tv = t0 / √(1-v^2/c^2)

For A, 31.25√ (1-(0.8)^2 = 18.75 years
For B, 41.67√ (1-(0.6)^2 = 33 years

So B will be older, arriving (33-18.75)-(41.67-18.75) = 4.2 years after A :music:
 

Fizzy_Cyst

Well-Known Member
Joined
Jan 14, 2011
Messages
1,189
Location
Parramatta, NSW
Gender
Male
HSC
2001
Uni Grad
2005
re: HSC Physics Marathon Archive

Question:

3 moons, X, Y and Z are in orbit around the same planet. The moons have identical orbital speeds, but masses of M, 9M and 25M respectively. Determine the ratio of their orbital radii and justify your answer.
 

jyu

Member
Joined
Nov 14, 2005
Messages
623
Gender
Male
HSC
2006
re: HSC Physics Marathon Archive

Question:

3 moons, X, Y and Z are in orbit around the same planet. The moons have identical orbital speeds, but masses of M, 9M and 25M respectively. Determine the ratio of their orbital radii and justify your answer.
Find the ratio of the forces of gravity on the moons.
 
Status
Not open for further replies.

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top