• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

Physical Application of Cal (1 Viewer)

Joined
Feb 6, 2007
Messages
628
Location
Terrigal
Gender
Male
HSC
2008
once you get the expression for velocity
change cos2t into 2cos^2t - 1

then you have v=cost-2cos^2t-1
set v=0
and the discriminant is less than zero, therefor never = 0

therefore never at rest
 
Last edited:

lyounamu

Reborn
Joined
Oct 28, 2007
Messages
9,998
Gender
Male
HSC
N/A
tacogym27101990 said:
once you get the expression for velocity
change cos2t into 2cos^2t - 1

then you have v=cost-2cos^2t-1
set v=0
and the discriminant is less than zero, therefor never = 0

therefore never at rest
That's brilliant. Thanks.

By the way, what about this one:

A body is moving with simple harmonic motion in a straight line. It has an amplitude of 10 metres
and a period of 10 seconds. How long would it take for the body to travel from one of the extremities of its path of motion to a point 4 metres away?

 

Aerath

Retired
Joined
May 10, 2007
Messages
10,169
Gender
Undisclosed
HSC
N/A
Oh, changing cos2t using double angle formula was genius.
 

lyounamu

Reborn
Joined
Oct 28, 2007
Messages
9,998
Gender
Male
HSC
N/A
Aerath said:
Oh, changing cos2t using double angle formula was genius.
Yeah, that's something to note. Really good question, that was.
 

vds700

Member
Joined
Nov 9, 2007
Messages
861
Location
Sydney
Gender
Male
HSC
2008
lyounamu said:
That's brilliant. Thanks.

By the way, what about this one:

A body is moving with simple harmonic motion in a straight line. It has an amplitude of 10 metres
and a period of 10 seconds. How long would it take for the body to travel from one of the extremities of its path of motion to a point 4 metres away?

wow someones pretty busy lol.

let x = 10sin(pi/5)t
Sketch this graph
when x = 10 (extremity)
10 = 10sin(pi/5)t
sin(pi/5)t = 1
(pi/5)t = pi/2
t = 5/2

when it is 4m away from this point, it is 6m away from the origin.
6 =10sin(pi/5)t
sin(pi/5)t = 3/5
(pi/5)t = 0.6435, 2.4981
t = ..., 3.9758 we are only interested in the second solution as this is when it is at 6m after being at 10m.

Time traken to be 4m away = 3.9758 - (5/2) = 1.4758 s.
 

lyounamu

Reborn
Joined
Oct 28, 2007
Messages
9,998
Gender
Male
HSC
N/A
vds700 said:
wow someones pretty busy lol.

let x = 10sin(pi/5)t
Sketch this graph
when x = 10 (extremity)
10 = 10sin(pi/5)t
sin(pi/5)t = 1
(pi/5)t = pi/2
t = 5/2

when it is 4m away from this point, it is 6m away from the origin.
6 =10sin(pi/5)t
sin(pi/5)t = 3/5
(pi/5)t = 0.6435, 2.4981
t = ..., 3.9758 we are only interested in the second solution as this is when it is at 6m after being at 10m.

Time traken to be 4m away = 3.9758 - (5/2) = 1.4758 s.
Thanks, Andrew. At this rate, I will get my ass kicked in Trials by everyone in 4 Unit class. I don't any miracle like 100% in MX1 will ever happen again. I am gone....
 

vds700

Member
Joined
Nov 9, 2007
Messages
861
Location
Sydney
Gender
Male
HSC
2008
lyounamu said:
Thanks, Andrew. At this rate, I will get my ass kicked in Trials by everyone in 4 Unit class. I don't any miracle like 100% in MX1 will ever happen again. I am gone....
no worries man. Dw you'll be fine, i have barely done much study for MX1, and catholic paper has the potential to be an absolute nightmare lol. I'm not expecting anywhere near 100%.
 

Jachie

it ain't easy being white
Joined
Jun 30, 2006
Messages
1,662
Gender
Female
HSC
2008
breaking said:
more like physical appreciation of cal.
more like jachie.
ahahahahaha fucking lol
 

hon1hon2hon3

Member
Joined
Jul 26, 2008
Messages
110
Gender
Male
HSC
2008
Just to make things clear"Er" , the period is 10 , soo T = 10 . T also equals to (2 pie)/n , thus n = pie/5 . Which is what is used in that solution above
 

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

Top