2009 Physics Unit 3 Exam Suggested Solutions

[TrueTears]

Here's my answers, is this what you guys got?

AOS1
1. 2.67
2. inelastic, initial kinetic energy does not equal final kinetic energy
3. 2560
4. Arrow to centre of circle
5. 500
6. 1.25
7. 600
8. 480
9. (Can't remember exactly what I wrote) Apparent weightlessness occurs when the only force acting on an object is due to gravity. The object feels no normal reaction force, hence it feels "weightless" etc etc
10. 45
11. 135
12. 8.37
13. Arrow pointing to centre of earth
14. 15260

AOS2
1. 4.29
2. 0.82
3. 0.23
4. 0.05
5. OFF OFF OFF ON ON ON
6. 300
7. Clips when V_in is 30mV , inverted
8. B, A, C, B
9. 5000
10. 1000
11. increased

Structures:
1. D
2. D
3. A
4. D
5. D
6. B
7. B
8. D
9. A
10. D
11. C
12. C
13. C

[Over9000]

all same except I did 720 instead of 480 for weight question  :tickedoff: :tickedoff: :tickedoff:

[Damo17]

all same except I did 720 instead of 480 for weight question  :tickedoff: :tickedoff: :tickedoff:

A few people from my school did that as well. I wrote 480N.

[junkie1999]

Since it is going up at 5m/s, then deccelerates at 2m/s/s the acceleration would be in the downward direction, same as the acceleration due to gravity. Adding these together gives an acceleration of 12m/s/s which results in a weight of 720N.  I hope that's right

[danieltennis]

Since it is going up at 5m/s, then deccelerates at 2m/s/s the acceleration would be in the downward direction, same as the acceleration due to gravity. Adding these together gives an acceleration of 12m/s/s which results in a weight of 720N.  I hope that's right

I just got
Fnet = mg - N
60 * 2 = 60 * 10 -N
N = 480 N

And also you know that the Normal reaction force must be smaller than the  previous q because Fnet is downwards since its decelerating. Therefore, W > N

[TrueTears]

Since it is going up at 5m/s, then deccelerates at 2m/s/s the acceleration would be in the downward direction, same as the acceleration due to gravity. Adding these together gives an acceleration of 12m/s/s which results in a weight of 720N.  I hope that's right

Let up be positive

[Over9000]

Since it is going up at 5m/s, then deccelerates at 2m/s/s the acceleration would be in the downward direction, same as the acceleration due to gravity. Adding these together gives an acceleration of 12m/s/s which results in a weight of 720N.  I hope that's right

Omfg, that exactly my thinking, but then I realised im pretty sure its wrong, the answer is 480N im sure, sigh, I suk at logic

[appianway]

It's definitely 480 N.

Obviously I don't have my exam here with me, but I think all of my answers were the same as the iTute ones... I might be getting a derived score anyway though, but it's a relief to know that I didn't fail.

Still annoyed at the simplicity of the exam though.

[NE2000]

480 is right...

Does anyone know why the projectile question gave a page of working and was worth four marks?

[TrueTears]

480 is right...

Does anyone know why the projectile question gave a page of working and was worth four marks?

No idea, teacher said it was ridiculous.

[hauhau]

what was question 12 for AOs1 again?

[NE2000]

what was question 12 for AOs1 again?

Vertical circular motion

N=0

Find v

[Damo17]

what was question 12 for AOs1 again?

Vertical circular motion. Min speed at top when inside loop.

Working:
10=v^2/7 , v=8.37

[hauhau]

tks... i think i got 90 xD

[danieltennis]

480 is right...

Does anyone know why the projectile question gave a page of working and was worth four marks?

just reminded me of the q that required you to draw a simple graph in the methods exam 1 last year. It was also worth four marks.

Edit: 1000 POSTS. IM part of the VN furniture