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March 28, 2024, 08:31:13 pm

Author Topic: QCE Physics Questions Thread  (Read 23471 times)

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A.Rose

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Re: QCE Physics Questions Thread
« Reply #30 on: August 04, 2020, 03:00:02 pm »
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Hello

I just need some help with this question - a little confused with what is happening...what is the stopping length?
Thank you!

Bri MT

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Re: QCE Physics Questions Thread
« Reply #31 on: August 04, 2020, 03:03:42 pm »
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Hey!

It's asking you how much distance the truck will cover before coming to a stop.



A.Rose

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Re: QCE Physics Questions Thread
« Reply #32 on: August 04, 2020, 03:12:27 pm »
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Oh ok, so its how much distance the truck will cover on the ramp before stopping...? Just need another clue. I'm not given its mass or anything just initial velocity and an angle. Usually, inclined plane Q's I need the parallel component...?

Bri MT

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Re: QCE Physics Questions Thread
« Reply #33 on: August 04, 2020, 03:21:45 pm »
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Oh ok, so its how much distance the truck will cover on the ramp before stopping...? Just need another clue. I'm not given its mass or anything just initial velocity and an angle. Usually, inclined plane Q's I need the parallel component...?

Yeah it's how much distance the truck would cover on the ramp before stopping.

This isn't a standard inclined planes question, it's about using the constant acceleration formulas (keeping in mind that unlike weight which would need you to know mass, acceleration due to gravity is constant on the surface of Earth - combine this with knowing the angle).

You've been given initial velocity & you set final velocity equal to 0 (because its stopping distance)

A.Rose

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Re: QCE Physics Questions Thread
« Reply #34 on: August 04, 2020, 04:21:54 pm »
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Oh, of course, thank you!

schoolstudent115

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Re: QCE Physics Questions Thread
« Reply #35 on: August 04, 2020, 04:41:06 pm »
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Hello

I just need some help with this question - a little confused with what is happening...what is the stopping length?
Thank you!
You can also use energy to solve this (I prefer this method).
Initial KE: 1/2 * m * (16.7)^2.
Work done by ramp = L*mg*sin(15), L is the length  (this is just W = Fs)
Then equate the two, the masses will cancel out.
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matthew hay

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Re: QCE Physics Questions Thread
« Reply #36 on: August 26, 2020, 06:41:41 pm »
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Hi there,

Do you or anyone know if there is an annotated syllabus? or even annotated Units 4 syllabus?? Please reply no if not (it saves me the extravagant search!

Thanks and kind regards, Matt

Bri MT

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Re: QCE Physics Questions Thread
« Reply #37 on: August 26, 2020, 07:45:08 pm »
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Hey,

I don't know of any physics syllabus annotations but if this is something you're really interested please feel free to let me know!

matthew hay

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Re: QCE Physics Questions Thread
« Reply #38 on: August 29, 2020, 06:56:17 pm »
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Hi Bri MT,

Yes, an annotated syllabus would very helpful and useful !!!   :D

jasmine24

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Re: QCE Physics Questions Thread
« Reply #39 on: November 05, 2020, 07:15:33 am »
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Hi, would anybody have any examples on "interpreting graphical representations of electrical potential difference vs electric current data to find resistance using its gradient and its uncertainty". I couldn't find any that also found the uncertainty and I'm unsure as to how to do that
Thank u!

Bri MT

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Re: QCE Physics Questions Thread
« Reply #40 on: November 06, 2020, 11:18:57 am »
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Hi, would anybody have any examples on "interpreting graphical representations of electrical potential difference vs electric current data to find resistance using its gradient and its uncertainty". I couldn't find any that also found the uncertainty and I'm unsure as to how to do that
Thank u!

Hey,

I'll attach some images later today but remember that this just comes from Ohm's law V=IR  => V/I =  rise/run = gradient = R

In regards to uncertainty, what's the steepest line of best fit given your uncertainty? What's the least steep line of best fit? Constructing these will give you your range of values for R and hence your uncertainty.

Hope this helps!

K.Smithy

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Re: QCE Physics Questions Thread
« Reply #41 on: November 06, 2020, 06:25:13 pm »
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Hi everyone!

I have been talking to a few people about this question and we haven't been able to come to an agreed upon answer  :P



For part a, some think that the charge of Q2 is negative and Q1 is positive: due to the fact that they opposite charges the electric field strength would cancel out in the middle. Furthermore, the electric field strength is negative as you approach Q2 - therefore, Q2 has a negative charge.
Others think that both Q1 and Q2 are positive: Coulomb's law states that opposite charges attract and like charges repel - so that would explain the fact that the electric field strength is 0 in between the two point charges (if both are positive, they will repel each other).

I can see both sides, but I don't know which one is correct.

Thanks,
Katelyn :)
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Bri MT

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Re: QCE Physics Questions Thread
« Reply #42 on: November 08, 2020, 01:28:08 pm »
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Hi K.Smithy! :)

Q2 is positive, because of the zero as well as because it goes from positive to negative. Electric field strength is described in terms of the impact of a positive charge at that point in space, not in terms of how the two charges present would interact so the second pov doesn't really work despite it showing physics knowledge.

Good question - it's an interesting one that I can easily see being one people would argue about after an exam

K.Smithy

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Re: QCE Physics Questions Thread
« Reply #43 on: November 08, 2020, 01:34:13 pm »
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Hi K.Smithy! :)

Q2 is positive, because of the zero as well as because it goes from positive to negative. Electric field strength is described in terms of the impact of a positive charge at that point in space, not in terms of how the two charges present would interact so the second pov doesn't really work despite it showing physics knowledge.

Good question - it's an interesting one that I can easily see being one people would argue about after an exam

Awesome! Thank you so much :)
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Bri MT

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Re: QCE Physics Questions Thread
« Reply #44 on: November 08, 2020, 04:18:53 pm »
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Awesome! Thank you so much :)

No worries!

For questions like this I would really recommend drawing a field diagram to help you understand why the answer is what it is. Once you've drawn it you should be able to see that for positive -> negative the field is constantly from q1 to q2 but that for positive -> positive it isn't since both positives are trying to push positive charges away & therefore are acting in opposite directions.