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# Surely this is wrong... watch

1. Whilst marking question 5 on this paper:

http://filestore.aqa.org.uk/subjects...W-QP-JAN11.PDF

Something has stumped me.

For c) you have to work out the time period of a cycle, which is 1/50. This comes to 0.02 seconds.

The x axis on the diagram is in milliseconds to surely you do 0.02*1000 to work out the time period in milliseconds which is 20ms

If this is the case then why does the mark scheme's diagram show that the time period is 0.02ms????

The mark scheme says accept either 20 or 0.02 as the time period, this doesn't seem right...

Mark Scheme:

http://filestore.aqa.org.uk/subjects...W-MS-JAN11.PDF

Thank you
2. (Original post by Nick-F007)
Whilst marking question 5 on this paper:

http://filestore.aqa.org.uk/subjects...W-QP-JAN11.PDF

Something has stumped me.

For c) you have to work out the time period of a cycle, which is 1/50. This comes to 0.02 seconds.

The x axis on the diagram is in milliseconds to surely you do 0.02*1000 to work out the time period in milliseconds which is 20ms

If this is the case then why does the mark scheme's diagram show that the time period is 0.02ms????

The mark scheme says accept either 20 or 0.02 as the time period, this doesn't seem right...

Mark Scheme:

http://filestore.aqa.org.uk/subjects...W-MS-JAN11.PDF

Thank you
Hey!
I'm not an AQA student, but I think you're right. Time period would be 0.02 s or 20 ms. They're probably accepting both as they don't want to cut marks on that point... I know it's weird but sometimes they overlook such things which is why they're accepting both values... still, you could probably ask your teacher or check the examiner report if it's provided.

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