Physics Unit 4 JUNE 11/6/12

[étudiante]

the velocity wil be 0.18 ok did u halve the distance

yeah i did!
look what i did:
a = -xw^2 , w = (0.89/0.035) and square root = 5.04
v = -Aw sinwt = 0.07 * 5.04 * 1 = 0.35 -______________________________-

 

[étudiante]

Well, apparently, i need to halve the 70mm when i use it in the v eqn again, but WHY????? dont we want Amplitude there? :S and Amplitude should be 70mm right? :S

 

[*Sandra*]

yeah i did!
look what i did:
a = -xw^2 , w = (0.89/0.035) and square root = 5.04
v = -Aw sinwt = 0.07 * 5.04 * 1 = 0.35 -______________________________-

wait let me check

 

[*Sandra*]

Well, apparently, i need to halve the 70mm when i use it in the v eqn again, but WHY????? dont we want Amplitude there? :S and Amplitude should be 70mm right? :S

ya u hve 2 and 70 mm is the total distance 4 1 complete oscillation look they said total distance so i understood it ths way and also i hve a doubt in wat's the diff between x and A

 

[étudiante]

wait let me check

Why do halve the amplitude in the v equation?

 

[étudiante]

ya u hve 2 and 70 mm is the total distance 4 1 complete oscillation look they said total distance so i understood it ths way and also i hve a doubt in wat's the diff between x and A

i know, but we need to do that for the first eqn as we only want x (that is max displacement) in that equation BUT for the velocity equation its A (which IS the total distance moved). So y do we halve it? :S

 

[*Sandra*]

Why do halve the amplitude in the v equation?

im really confused and is there a diff between x and A and maybe they havle it bcz total dis is 70 of it went 2 times through 35 mm i guess its 1 complete oscillation isn't it?

 

[*Sandra*]

i know, but we need to do that for the first eqn as we only want x (that is max displacement) in that equation BUT for the velocity equation its A (which IS the total distance moved). So y do we halve it? :S

amplitude is also the max distance frm the equilibrium position

 

[étudiante]

im really confused and is there a diff between x and A and maybe they havle it bcz total dis is 70 of it went 2 times through 35 mm i guess its 1 complete oscillation isn't it?

LOLZ m confused too yeah but in the v equation we NEED the distance for 1 oscillation, thats what is A

 

[étudiante]

amplitude is also the max distance frm the equilibrium position

Sure?

 

[*Sandra*]

LOLZ m confused too yeah but in the v equation we NEED the distance for 1 oscillation, thats what is A

u kno smethng i really hate phy and the most thng i hate in phy is astrophysics

 

[*Sandra*]

Sure?

ya its the max displacement frm equlibrium position look in the pearson book pg 151 the pendulum dynamics paragraph 2

 

[étudiante]

u kno smethng i really hate phy and the most thng i hate in phy is astrophysics

AGREED!!!! 110%
HATE IT

 

[étudiante]

ya its the max displacement frm equlibrium position look in the pearson book pg 151 the pendulum dynamics paragraph 2

Oksay.. i'll check in a sec
Thanks so much :') n the rest of the question i did it, dats easy right?

 

[étudiante]

ya its the max displacement frm equlibrium position look in the pearson book pg 151 the pendulum dynamics paragraph 2

Thanks SO much... now i get it why i was getting so many of my oscillations numericals wrong even though my method was corrct -__-"
THanks a LOT

 

[*Sandra*]

Thanks SO much... now i get it why i was getting so many of my oscillations numericals wrong even though my method was corrct -__-"
THanks a LOT

wlc ok i ned u 2 explain me the last part of tht que and y they tuned the damper 2 the natural frequency of the bridge?

 

[étudiante]

wlc ok i ned u 2 explain me the last part of tht que and y they tuned the damper 2 the natural frequency of the bridge?

well at resonant frequency, maximum energy absorption occurs so if they have the same natural frequency, then the bridge will give the energy to the springs and as they are damped heavily, the energy will be dissipated... no energy means the bridge wont vibrate

 

[*Sandra*]

well at resonant frequency, maximum energy absorption occurs so if they have the same natural frequency, then the bridge will give the energy to the springs and as they are damped heavily, the energy will be dissipated... no energy means the bridge wont vibrate

ok nw the damper shld equal the bridge's natural frequency?and i kno tht it wil tranfer energy 2 the bridge?

 

[étudiante]

ok nw the damper shld equal the bridge's natural frequency?and i kno tht it wil tranfer energy 2 the bridge?

yes for maximum enegry transfer :to occur

 

[étudiante]

I solved question 5 and 6 as well, what did u want to know in dat?