i JUST CANT SEEM TO FIGURE THIS ONE OUT!!!

A transverse wave on a cord is given by y(x, t) = 0.12 sin(3.0 x – 15.0 t), where Y,
and x are in meters and t is in second. At t = 0.20 s, what are the displacement and
velocity of the point on the cord where x = 0.60 m?

answer: -0.11

i tried punching in the values and doing random shit to the equation...so LOST!!!

for position just plug the values in.
for velocity take derivative and again plug in values


Your problem is more than likely the fact that your calculator is not in radians.

FYI i got -0.11=y
i also get y'(x,t)= -3cos(3x-15t) (where x is held constant) => y'(0.6,0,2)=-1.087

Might have made mistake with the velocity since I'am kinda in a rush right now.

Omg You Will Not Believe That I Legit Spent An Hour Trying To Figure Out What I Was Doing Wrong When The Whole Time My Calculator Was In Degrees......thank You!!!!!!

www.cramster.com <-- Yahoo answers for physics. Saved my capa mark this year SO many times.

Originally Posted by Sintos

www.cramster.com <-- Yahoo answers for physics. Saved my capa mark this year SO many times.

Is making an account free? lol

^From what I saw when I stumbled on to it during Maths...nope. :/

Originally Posted by Strategy

Is making an account free? lol

yeah it is. There is another one called course hero which you have to pay for.

cramster is free for random yahoo type questions. IF you want solutions to textbooks you need to pay.

If I ever take a course that has a textbook on it I will probably pay the 5 dollars a month for exam month. Not expensive at all.

Freaking dental club cost that much and there was two pointless meetings... xD

Originally Posted by Sintos

cramster is free for random yahoo type questions. IF you want solutions to textbooks you need to pay.

If I ever take a course that has a textbook on it I will probably pay the 5 dollars a month for exam month. Not expensive at all.

Freaking dental club cost that much and there was two pointless meetings... xD

whats dental club?!?!!

Originally Posted by smarties13

whats dental club?!?!!

It is literally a club about every thing dental.

However, it was very poorly organized this year. They reeled me in saying they would be "holding" a free practice DAT. Which later turned out to be held by Kaplan or something and they had nothing to do with it.

They asked us to show up to a meeting, took 5 dollars from everyone, told us what they were going to do throughout the year (Bring in Kaplan people, tour Western, Slide shows about requirements to get it, etcetc), After the first meeting they pretty much blew everyone off until me and my friend were overheard talking about it in animal physio. The next day or something we got an email saying they have a meeting about dental school prereqs.

I really feel like they made the club just to put on their resumes / applications when applying to dental schools. The people were nice and I'm not blaming them, they need high averages and I'm sure studying was important (Pres is in biochem or something) but it was disappointing being apart of a club that did nothing after saying it would do so much.

Next year it may be better though, my friend got Vice Pres.

can someone help me with 2 questions? been stuck for a while

the answer is c

the answer is b and I dont know what should i hold as a constant

Originally Posted by smarties13

i JUST CANT SEEM TO FIGURE THIS ONE OUT!!!

A transverse wave on a cord is given by y(x, t) = 0.12 sin(3.0 x – 15.0 t), where Y,
and x are in meters and t is in second. At t = 0.20 s, what are the displacement and
velocity of the point on the cord where x = 0.60 m?

answer: -0.11

i tried punching in the values and doing random shit to the equation...so LOST!!!

um, may be you are working in degrees? Try switching your calculator to radians mode?

Originally Posted by macsci

um, may be you are working in degrees? Try switching your calculator to radians mode?

That's totally not what the OP's reply said.

Originally Posted by justinsftw

That's totally not what the OP's reply said.

Was quick to reply, saw it after lol.

Originally Posted by Kayee

can someone help me with 2 questions? been stuck for a while

the answer is c

the answer is b and I dont know what should i hold as a constant

For the first one: the particle cannot be travelling on the x-axis since it only ever moves up and down (i.e. y-axis), so eliminate all answers that say "in the ___ x-direction". Next, eliminate the option of it being zero because the particle is not at a local max/min at t=0 (the velocity, which is the derivative of this curve, can only be zero at a local max/min). Now, since the wave equation is y(x,t)=4sin(2x-3t), we know that the wave is moving in the positive x direction (because it's -3t, not +3t). So, if the wave is moving right, that means the specified point can only be moving UP (the crest would be moving towards the specified point, so the particle must be moving up). Therefore, the answer is "c", the particle's instantaneous velocity is in the positive y-direction.

For the second one: Remember the equation velocity of string v=(T/linear mass density)^(1/2) ? Keep T constant. And, of course, frequency is pretty much always constant since frequency depends on the source!