Physics HSC Predictions/Thoughts (3 Viewers)

[notme123]

Yep, ans to Q18 is (a). With accelerating motion (from rest) in both x and y directions then the trajectory is linear. (Even if the accelerations are unequal.) After the x accel is removed (E field removed) it follows the usual parabolic trajectory.

well if you say so but idk we'll see.

I only got to look at the paper late tonight so have just skimmed through, but my prelim MC solns are
1 ........... 5
B C D B A

6 ...........10
D C D C B

11 ........ 15
A D B C C

16 ....... 20
A C A A D

i got root 3 for 20 as well but i thought it was c whoops, maybe not idk

 

[notme123]

I only got to look at the paper late tonight so have just skimmed through, but my prelim MC solns are
1 ........... 5
B C D B A

6 ...........10
D C D C B

11 ........ 15
A D B C C

16 ....... 20
A C A A D

theres a few things wrong here i think, from what i can see 16, 14 are wrong. 14 is wrong because they dont accelerate at the same rate i think cuz their masses are different.
i think answer for 14 is a because yes they do accelerate towards each other, the moons acceleration is just more pronounced cuz its lighter and thus requires less force to accelerate.
16 i didnt get a i got b but maybe im wrong. a mistake couldve been you didnt multiply the power by 60

 

[uart]

theres a few things wrong here i think, from what i can see 16, 14 are wrong.

Thanks notime, you're absolutely right. I only skimmed through this late last night and didn't notice that mass loss was per minute (yes I calculated per second).

The other question 14 again you are correct. Equal an opposite forces, not acceleration. Thanks for pointing that out as I had a nagging doubt that "a" was also correct on that one. Now I see "a" is the *only* correct answer, and MC is much nicer when there's only one correct answer!

 

[uart]

well if you say so but idk we'll see.

With const acceleration from rest you get:




Eliminate "t" to get a linear relation between x and y.

i got root 3 for 20 as well but i thought it was c whoops, maybe not idk

- KE increases from (2 phi - phi) to (4 phi - phi), so KE is tripled.
- v is proportional to sqrt(KE), so v is increase by factor sqrt(3)
- r is proportional to v.

 

[notme123]

- KE increases from (2 phi - phi) to (4 phi - phi), so KE is tripled.
- v is proportional to sqrt(KE), so v is increase by factor sqrt(3)
- r is proportional to v.

oh dw in my calc i got root 3 but i thought root 3 r was c but maybe i put d idk

also someone posted soln on fb and basically everything matches including the projectile/electric feild one

 

[uart]

oh dw in my calc i got root 3 but i thought root 3 r was c but maybe i put d idk

Ok I see, I hate it when that happens. MC can be annoying like that, with so little time it's very easy to know your stuff but still make some really minor mistakes that will lose you the marks. Meanwhile someone who knows close to nothing can often jag about 50%.

 

[BobMarleytheGoat]

I only got to look at the paper late tonight so have just skimmed through, but my prelim MC solns are
1 ........... 5
B C D B A

6 ...........10
D C D C B

11 ........ 15
A D B A C

16 ....... 20
B C A A D

Edited 14 and 16 thanks to notime123

Can someone explain why 15 is C. Does changing the first polariser not do anything?

 

[notme123]

Can someone explain why 15 is C. Does changing the first polariser not do anything?

it doesnt do anything to I1 but since the angle between the polarising axes is changing, I2 will change according to malus' law.

 

[liv888]

Can someone explain why 15 is C. Does changing the first polariser not do anything?

cause it's unpolarised light, so I1 will always be half the intensity of the unpolarised light no matter the angle, I2 will change cause the angle between the first polariser and second is changing (since I1 is polarised)