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OCR B Physics H157/01 Fnd in Physics 24th May 2016

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Reply 40

jjcoolio

Diode question wasn't in syllabus as far as I know and all in all very little materials

Reply 41

jjcoolio

Grade boundary predictions?

Reply 42

swagmister

Original post by JZ0120

Well I think I definitely get this wrong.
I thought the acceleration was not constant due to the air resistant and it is decreasing to 0 as terminal velocity reached.

I can't remember if the question said or not but usually for those kind of questions they ignore air resistance

Reply 43

swagmister

Original post by jjcoolio

Grade boundary predictions?

In the old spec it was usually around 70% for an A and lots of people found it difficult maybe around 48 for an A?

Reply 44

danigr

The question said that they wanted to find the terminal velocity, which is reached when air resistance is equal to que force of gravity, velocity is constant and acceleration=0

Reply 45

metasysta

Original post by danigr

The question said that they wanted to find the terminal velocity, which is reached when air resistance is equal to que force of gravity, velocity is constant and acceleration=0

Yes but how can you calculate that from a time and a distance. There isn't enough info. You can't use suvat, and we aren't even told when it reaches terminal velocity.

Reply 46

peanutbutterjam

I almost cried at the end of this paper but then I remembered this doesn't actually count lol
(I even had a friend who forgot his calculator)

Reply 47

phoebeisgreat

Original post by peanutbutterjam

I almost cried at the end of this paper but then I remembered this doesn't actually count lol
(I even had a friend who forgot his calculator)

what? it doesn't count?

Reply 48

swagmister

Original post by danigr

The question said that they wanted to find the terminal velocity, which is reached when air resistance is equal to que force of gravity, velocity is constant and acceleration=0

But to reach terminal velocity won't it need to accelerate first?

Reply 49

peanutbutterjam

Original post by phoebeisgreat

what? it doesn't count?

These exams don't count towards the full a-level, we have to do another set of AS exams next year

Reply 50

blackcurrent101

I think that was an alright paper, we did the microwave experiment in class but with marshmallows instead of chocolate :h:

Spoiler

Reply 51

phoebeisgreat

Original post by peanutbutterjam

These exams don't count towards the full a-level, we have to do another set of AS exams next year

oh right, but unis will still look at your as grades i think...

Reply 52

jjcoolio

Anyone think paper 2 could be easier? The specimen was awful but potentially after that it could be OK?

Reply 53

Will487

Original post by metasysta

Yes but how can you calculate that from a time and a distance. There isn't enough info. You can't use suvat, and we aren't even told when it reaches terminal velocity.

If it had reached terminal velocity surely then all the forces would be balanced and it would be travelling at a constant velocity? As such, velocity = distance / time.

Reply 54

swagmister

Original post by Will487

If it had reached terminal velocity surely then all the forces would be balanced and it would be travelling at a constant velocity? As such, velocity = distance / time.

Was there a graph for this question?

Reply 55

Will487

Original post by swagmister

Was there a graph for this question?

I think there were two questions on terminal velocity - correct me if I'm wrong - one on paper cup cases, and the other which featured the graph and table on the last page.

Reply 56

swagmister

Original post by Will487

I think there were two questions on terminal velocity - correct me if I'm wrong - one on paper cup cases, and the other which featured the graph and table on the last page.

I remember using a graph to see the time at which it reaches Vt and then using Suvat with u as 0 because it accelerates to reach Vt

Reply 57

danigr

Original post by Will487

I think there were two questions on terminal velocity - correct me if I'm wrong - one on paper cup cases, and the other which featured the graph and table on the last page.