VCE Physics Question Thread!

[nkemobi13]

Hey guys, I was wondering if someone could please upload some answers to the 2016 vcaa physics exam
Thanks

[robibl476]

itute have the answers

[Gogo14]

Hey guys this is urgent. How do you calculate uncertainties for sine and arcsine functions. This is for my practical investigation about calculating refractive angles. thannnnnkkkkkkkssssss!!!!!!!!

[Buddster]

Hey guys this is urgent. How do you calculate uncertainties for sine and arcsine functions. This is for my practical investigation about calculating refractive angles. thannnnnkkkkkkkssssss!!!!!!!!

I found the following on some random forum, need verification:
If you have sin (1.5 ± 0.2) radians
The uncertainty is 0.2 Cos 1.5
(This must be in radians)

[wyzard]

Hey guys this is urgent. How do you calculate uncertainties for sine and arcsine functions. This is for my practical investigation about calculating refractive angles. thannnnnkkkkkkkssssss!!!!!!!!

A way to work out the uncertainty of sin and arcsin functions is by using the linear approximation:

Where delta x and y represent the uncertainty in the quantities x and y.

For example, suppose you measured x to be 1.0 rad with uncertainty of 0.1 rad, the uncertainty of sin x is then cos(1.0) * 0.1.

[dylang99]

Hi All,

I am having a little bit of trouble understanding how to work out this question. Any help would be much appreciated! 

A child is holding a garden hose at ground level and the water stream from the hose is travelling at 15 ms-1. which angle to the horizontal will result in the water stream travelling the greatest horizontal distance through the air?

[Buddster]

Hi All,

I am having a little bit of trouble understanding how to work out this question. Any help would be much appreciated! 

A child is holding a garden hose at ground level and the water stream from the hose is travelling at 15 ms-1. which angle to the horizontal will result in the water stream travelling the greatest horizontal distance through the air?

long way:
Use these two formulae for the x and y axis motion:

x=v*t=15t
y=u*t-a/2*t²=15t-5t^2

rearrange y for t in terms of y. Derive x in terms of y. Use d/dx=0 to find the maximum value for x, and for what y value that is. angle=arctan(y/x)

short way:
range formula: u²*sin(2*angle)/g

the max value of the function is where sin(2*a)=1, look at a sine graph

[Nicko912]

Does anyone know how to approach this question?

Thanks

[Buddster]

Does anyone know how to approach this question?

They're in equilibrium so the weight force and the electromagnetic force is equal.
The electromagnetic force is 3.55×10^4 multiplied by the charge in Columbus as the unit is N/C
MG=-3.55×10^4*c

Once you find c, divide by the charge of an electron to find the amount of electrons

[Nicko912]

They're in equilibrium so the weight force and the electromagnetic force is equal.
The electromagnetic force is 3.55×10^4 multiplied by the charge in Columbus as the unit is N/C
MG=-3.55×10^4*c

Once you find c, divide by the charge of an electron to find the amount of electrons

Thanks for the response, but how exactly do I find 'c'?

[Buddster]

Thanks for the response, but how exactly do I find 'c'?

You have the values for the mass an gravity (1.161×10^-14, 9. and rearrange

[peanut]

I asked this on the Chemistry thread, but I wanted to see if the same applies to Physics.

When working through a question, do I round to appropriate sig figs at each step, or just for the final answer? In most cases, it shouldn't matter, but what is the correct way of doing it? Similarly, do I use a rounded value for the next step in my calculation, or just use the full (as many decimal places as possible) value on my calculator?

Thanks!

[Buddster]

I asked this on the Chemistry thread, but I wanted to see if the same applies to Physics.

When working through a question, do I round to appropriate sig figs at each step, or just for the final answer? In most cases, it shouldn't matter, but what is the correct way of doing it? Similarly, do I use a rounded value for the next step in my calculation, or just use the full (as many decimal places as possible) value on my calculator?

Thanks!

Sig figs don't matter in physics! Best to keep within realms of the correct number though for readability and accuracy. For example: if the correct number of figures is 5, don't round to 1.

[Jakeybaby]

Sig figs don't matter in physics! Best to keep within realms of the correct number though for readability and accuracy. For example: if the correct number of figures is 5, don't round to 1.

Are you sure?
They certainly do here in SA, I'd assume that they would be assessed throughout Australia as they are extremely relevant to the accuracy of an answer.
I'd suggest the exact same method as what I suggested in the Chemistry thread.

[Syndicate]

Are you sure?
They certainly do here in SA, I'd assume that they would be assessed throughout Australia as they are extremely relevant to the accuracy of an answer.
I'd suggest the exact same method as what I suggested in the Chemistry thread.

Significant figures are not assessed VCE physics, which is a shame I guess.

To OP: like Buddster asserted, only round your answer to a sensible amount of numbers.