CSSA Physics (6 Viewers)

[Screamm]

qwerty did you get like 4.77x10^10?

 

[jamesfirst]

That is wrong because that formula assumes g is a constant value. However as an object moves further away from Earth the value of g changes. Many textbooks are horrible at explaining this concept.

Hmm. you have a point.

But I was taught in class to do this... so yeah... I'll argue


Edit: Actually, it shouldn't matter. Because they are asking for the initial work require to propel the object to such height. So I don't think the constancy of 'g' matters too much. Textbooks and teachers taught to just consider 'g' as a constant value. If you discuss it like that, then projectile motions wouldn't work.

 

[tomdoml]

Hmm. you have a point.

But I was taught in class to do this... so yeah... I'll argue


Edit: Actually, it shouldn't matter. Because they are asking for the initial work require to propel the object to such height. So I don't think the constancy of 'g' matters too much. Textbooks and teachers taught to just consider 'g' as a constant value. If you discuss it like that, then projectile motions wouldn't work.

Syllabus:
"-Define gravitational potential energy as the work done to move an object from a very large distance away to a point within the gravitational field."
Ep= -G(m1m2)/r

 

[Durka224]

Can anyone shed light on a Quanta to Quarks question that asked for the the wavelength of 'the first line in the balmer series'?

 

[jamesfirst]

Syllabus:
"-Define gravitational potential energy as the work done to move an object from a very large distance away to a point within the gravitational field."
Ep= -G(m1m2)/r

Ummm... yeah I know that. What's your point ? lol

 

[hscishard]

Ep is based on work. You should've used that Ep thing. You may still have gotten the right answer, who knows

 

[daniboy232]

so whats the answer for the potential energy question ?

 

[RandoM_TerroR]

0.0

 

[Qwertyuioplm]

Hmm. you have a point.

But I was taught in class to do this... so yeah... I'll argue


Edit: Actually, it shouldn't matter. Because they are asking for the initial work require to propel the object to such height. So I don't think the constancy of 'g' matters too much. Textbooks and teachers taught to just consider 'g' as a constant value. If you discuss it like that, then projectile motions wouldn't work.

Projectile motion is assumed to have a constant g as defined by its parabolic trajectory of constant downward acceleration and constant horizontal velocity.

The formula you used is an approximation of work done, an approximation that is only valid close to the surface to Earth. In questions that involve large radius, that formula results in extremely large inaccuracies and hence the integrated formula (change in gravitational potential energy) is used.

Try integrating Newton's Law of Gravitation in terms of r and you might understand why.

 

[clementc]

g is certainly not constant lol
but we approximate 9.8m/s^2 for points near the earth's surface
Isn't there an entire dot point that asks for reasons that account for the variation in g?

And just adding on to what qwerty said, integrate between limits from infinity to a distance r

 

[BobMac]

qwerty did you get like 4.77x10^10?

I got something pretty similar to that if I remember correctly

 

[FCB]

Was the value for Gpe negative or positive. I don't remember the question

Was it asking for work done or the Gpe at that point?

 

[FCB]

And you could work our the current either by f=bilSin(theta) ornT=fd then sub into torque formula. Same answer or 2 amps

 

[jamesfirst]

g is certainly not constant lol
but we approximate 9.8m/s^2 for points near the earth's surface
Isn't there an entire dot point that asks for reasons that account for the variation in g?

And just adding on to what qwerty said, integrate between limits from infinity to a distance r

Yes. There is a reason why they give you the value for 'g' in the chart.

 

[Joy_2575]

were there any questions on relativity?

 

[jamesfirst]

were there any questions on relativity?

Yes. There was one where u had to draw Simultaneity and explain it.

 

[Joy_2575]

Yes. There was one where u had to draw Simultaneity and explain it.

How would you draw simultaneity ? :S
Do you just draw the train and two different observers?

Also were there any experiments this year?

 

[Screamm]

How would you draw simultaneity ? :S
Do you just draw the train and two different observers?

Also were there any experiments this year?

yeah i did the train one with lightning strikes lol

you had talk about thompsons experiment and draw the setup of experiment to show lenz law

 

[FCB]

Did we have to talk about thompsons experiment? It had no helmholtz coil or it wasn't asking to measure the charge:mass ratio (his experiment) I didn't explain that v=e/b or any of that.

I mentioned thermionic Emmision

 

[Screamm]

Did we have to talk about thompsons experiment? It had no helmholtz coil or it wasn't asking to measure the charge:mass ratio (his experiment) I didn't explain that v=e/b or any of that.

I mentioned thermionic Emmision

i forgot they changed some of the questions in ours haha but yeah it wasn't in the standard only in mine because we haven't finished ideas to implementation yet :\.