The Physics PHYA2 thread! 5th June 2013

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Original post by `Jts

Only thing I'm not 100% on is the 6 marker. Anyone have any brief ideas on what it could be?

Nope

I was expecting something generic for unit 1, and then look at what we got for that!

I'd assume that they are going to do the same, so I have a horrible feeling they will do it on diffraction gratings or energy conversions. Or less likely, they will give us the standard 6 marker of describe an experiment, which is just to state what was mentioned a couple of pages back.

Reply 1021

Claree

Original post by StalkeR47

you mention the change is velocity will affect the horizontal motion. That is correct. But, if you say velocity will change the horizontal motion, that is incorrect. Ship changing speed would mean that the drag force from the water is increased and so the air resistance, so it is a factor that causes change in the horizontal force/motion.

What I don't get is why the mark scheme says that "acceleration/speed of the ship" is a correct answer to question 1c on the paper. Please could you explain this? :smile:

How can the ship's speed affect the horizontal component of the force exerted on the ship by the sail?

Reply 1022

Jack93o

do you guys think we need to know how to derive the fringe spacing and diffraction angle equation?

Reply 1023

masryboy94

Original post by Jack93o

do you guys think we need to know how to derive the fringe spacing and diffraction angle equation?

well since the syllabus says we need to know how to derive diffraction grating, im guessing we need to know that one lool, but i dont think we need to know for the fringe spacing, but that can be done too anyways

Reply 1024

Qari

Original post by masryboy94

question: what is the difference from saying you get a maxima\minima or bright\dark fringes or zero\first order?

maxima/minima can happen in both experiments while bright/dark fringes is fringe spacing, I think :smile:

Reply 1025

StalkeR47

Original post by Claree

What I don't get is why the mark scheme says that "acceleration/speed of the ship" is a correct answer to question 1c on the paper. Please could you explain this? :smile:

How can the ship's speed affect the horizontal component of the force exerted on the ship by the sail?

Think about. If you increase the speed, there is more air resistance and the drag (water) force. If you decrease the speed, there is less air resistance and the drag force from the water. Ship if moving horizontally, not vertically. So, these factors would affect the horizontal motion of the ship. :smile:

Reply 1026

masryboy94

Original post by Qari

maxima/minima can happen in both experiments while bright/dark fringes is fringe spacing, I think :smile:

but isnt a maxima a bright fringe which is the n order? and likewise for minima?

Reply 1027

`Jts

Original post by OliverG

Nope

Oh alright. Thanks! :smile:

Reply 1028

Qari

Original post by Claree

What I don't get is why the mark scheme says that "acceleration/speed of the ship" is a correct answer to question 1c on the paper. Please could you explain this? :smile:

How can the ship's speed affect the horizontal component of the force exerted on the ship by the sail?

Greater the speed, it's moving the more resistance on the sail :smile:

a=v/t

F=ma or F=mv/t meaning force is proportional to velocity, so as one increases so does the other :smile:

Reply 1029

Claree

Original post by StalkeR47

Doesn't the question want you to refer to the effect on the "horizontal force" on the ship exerted by the sail, not the ship's "horizontal motion"?

Reply 1030

StalkeR47

Original post by Qari

maxima/minima can happen in both experiments while bright/dark fringes is fringe spacing, I think :smile:

Dark/bright fringes are not the fringe spacing. Max is called bright and min is called the dark. There is no difference. :smile:

Reply 1031

Jimmy20002012

This is a really stupid question but what are the rearrangements of the dsintheta=nlambda?

Posted from TSR Mobile

Reply 1032

Claree

Original post by Qari

Greater the speed, it's moving the more resistance on the sail :smile:

a=v/t

F=ma or F=mv/t meaning force is proportional to velocity, so as one increases so does the other :smile:

Thanks!!! I understand now :biggrin:

Reply 1033

jasmintaa

can someone please tell me how many significant figures we're meant to go to? Physics is so vague :frown:

Reply 1034

StalkeR47

Original post by Claree

Doesn't the question want you to refer to the effect on the "horizontal force" on the ship exerted by the sail, not the ship's "horizontal motion"?

Force affects the motion. So it is the same thing. And, you can just state increasing the speed- would be 1 factor. Wind force is another factor. :smile:

Reply 1035

Claree