# Exam thoughts?? (1 Viewer)

#### kashkow

##### Active Member

These were mine:

1. D
2. C
3. A
4. A
5. D
6. D
7. B
8. D
9. A (had put B at first, changed to A... Not to sure between two)
10. C
11. B
12. B
13. B
14. B (lol so many B's)
15. C
16. B
17. C
18. C
19. A
20. B

What did you guys get?

#### WrittenLoveLetters

##### 배고파
I don't even remember what I did in the exam anymore.

I'm just happy that I wrote something for everything LOL

#### mqixdjexx

##### Member
I just thought about what it feels like when youre in a car and you go over a hill, you feel that weightless feeling. Same thing when an elevator comes to the top. the acceleration due to gravity seems to get smaller, and so it hangs in the air for longer. i got C
Isn't the answer A though. The lift is slowing down but its going upwards as it says top floor of the building. This means as particle is launched, it goes up so the vertical distance lowers and hence it stays in the air for a lower time (relative to when lift was stationary) and hence shorter range hence so I got A. Could be wrong though.

#### Ambility

##### Active Member
Isn't the answer A though. The lift is slowing down but its going upwards as it says top floor of the building. This means as particle is launched, it goes up so the vertical distance lowers and hence it stays in the air for a lower time (relative to when lift was stationary) and hence shorter range hence so I got A. Could be wrong though.
The ball's trajectory is impacted by the elevators acceleration, not velocity. The elevator could be going extremely fast outwards from Earth but as long as it doesn't accelerate, the trajectory would remain unchanged due to it being in an inertial frame of reference. Since the elevator is decelerating after upwards vertical velocity, it is similar to accelerating downwards from stationary. It is therefore C.

#### Green Yoda

##### Hi Φ
For Q17: The lift slows down creating a slightly negative or acceleration in the opposite direction thus decreasing the steepness of the gradient as time of flight increases. Therefore C

#### ml125

##### Well-Known Member
Went okay considering how meep I was - praying for b6 but lol I'll be happy with a b5 :') rip all rounders

#### mqixdjexx

##### Member
Went okay considering how meep I was - praying for b6 but lol I'll be happy with a b5 :') rip all rounders
Lol people here are predicting 85 raw for b6 cut off

#### ml125

##### Well-Known Member
Lol people here are predicting 85 raw for b6 cut off
Doubt I did that well at this point rip

#### DatAtarLyfe

##### Booty Connoisseur
OMFG i just realised the diagram said electric field and not magnetic field.
Sigh, well there goes one mark

#### Tahmeed1998

##### New Member
What did everyone get for Q3? I thought that since the electron wasnt moving, it wouldnt be affected by the magnetic field (motor effect only applies to moving charges [right???])

But also like, electric field would move the electron, and that would end up in the electron being affected by the mag field UGH WHY

#### tommo727

##### Member
What did everyone get for Q3? I thought that since the electron wasnt moving, it wouldnt be affected by the magnetic field (motor effect only applies to moving charges [right???])

But also like, electric field would move the electron, and that would end up in the electron being affected by the mag field UGH WHY
I said C (only electric field) but now you say that it is a very badly worded and slightly ambiguous question. But as it is an early question I think ovethinking is not needed and they will accept C (hopefully).

#### henryg124

##### New Member
I said C (only electric field) but now you say that it is a very badly worded and slightly ambiguous question. But as it is an early question I think ovethinking is not needed and they will accept C (hopefully).
I also said C for the reason that electric field effects all electrons but magnetic field only effects moving electrons

Exam was easy

#### le_420_prince

##### New Member
What did everyone get for Q3? I thought that since the electron wasnt moving, it wouldnt be affected by the magnetic field (motor effect only applies to moving charges [right???])

But also like, electric field would move the electron, and that would end up in the electron being affected by the mag field UGH WHY
yep i thought this during test... bloodt ambigous

#### ThreeSciences

##### Member
Once the electron moves, it's no longer stationary, so it has to be C. Otherwise, they're mental.

#### Maths Champion

##### New Member
30a?

The energy firstly has to come from somewhere. Since the brick falls to the ground, its elevation is changing. This means that the energy comes from gravitational potential energy.

Maximum energy = (Egpe at initial altitude) - (Egpe at initial altitude - 1 metre)

Maximum energy = 7.5J (approx)

Can someone verify that they got this too?

30b?

When the switch is open, the brick will be more free to fall than if the switch is closed. When the switch is closed, the lightbulb acts as a load and resists the motion of the turning generator.

EDIT: Request for somebody, can somebody please tell me what they got for Q17 MCQ? I chose C as the answer (trajectory is slightly above original trajectory). This was the elevator question.

For the multiple choice, what did you guys get for question 14, the period?

t/2?

#### kashkow

##### Active Member
Man I completely missed in the exam that magnetic fields only exert a force on moving particles... There goes a mark in the MC for me.

And to all those who think it's ambiguous I'm pretty sure it is C. Note that it's asking for the force at this particular INSTANT, where the particle is stationary. Additionally, just because there is a force acting on the particle does not mean that it necessarily starts to move. There may be another factor that keeps it in place ie. stationary.

Like if you take a cup of coffee for example, you can be exerting a force onto it by your hand, but it may still be stationary because there could be something holding it back, like a wall. There is still a force acting on the cup by your hand but it's not moving... That just goes to show that you could have a force acting on a body which does not necessarily mean movement...

I'm not suggesting this question says that there are external factors keeping the electron in place (though it is implied by the word 'stationary'). I'm just clarifying that by exerting a force on an electron DOESN'T necessarily mean it will move (and it is highlighted in the question by the word 'stationary') and therefore there is only the electric field exerting a force, not the magnetic field. Therefore A can't be an option...

I hope this clears some ambiguities. That's just my 2c. (Though if BOSTES decides it's ambiguous and let's A be an answer, I'd still be happy haha )

Same.

#### marioyoshi

##### New Member
question 3 was ambiguous as fuck. tehcnically both are correct. the board should definately accept both man they suck at making multi