Physical Sciences P1 Gr 12 July 2021: Additions/Corrections/Clarifications to the marking guideline

Free State teachers - the YouTube video with the memo discussion is still available. Use the same link as for the live broadcast. You can still access it.

The following notes may help further. These are aspects for which enquiries were received after the memo discussion or where we want to give a bit more info to you.

Look at this post frequently for the next day or two until your marking is finished. New information will appear at the top.

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Click here for further info on questions:

2.2.2

4.1.4

4.1.5

6.2.2

7.2.3

7.2.4

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Q3.1.1

Some learners write down "9,8" or "-9,8" (unit is optional) without saying upward or downward. Apply the following rule in this case:

• If a learner indicates that he/she is taking down as negative, "-9,8" is worth two marks.
• If a learner indicates that he/she is taking down as positive, "9,8" is worth two marks.
• Without indicating what is taken as negative or positive, "-9,8" or "9,8" is only one mark; referring to the value. The direction mark is then lost.

It is so good this question was asked. It highlights the following important aspects. 

• Learners must know that a positive or negative is meaningless without an indication of what is chosen as the positive or negative direction. 
• Gravitational acceleration (g) is ALWAYS directed to the centre of the earth (we normally say downwards). 
• So, if downwards is chosen as negative, g = -9,8 m.s^-2. On its own, the negative is meaningless.
• The same is valid for choosing positive downward. Then one can say g = +9,8 m.s^-2. Once again, on its own the positive is meaningless.
•  Be careful of textbooks that say, for example, the 9,8 is negative for an object moving upwards, and positive for an object moving downwards, or vice versa. That is simply incorrect and unscientific. It could only be correct if the accompanying choice for direction is also given.

I hope this helps to emphasise a very important aspect.

Q6.1.1

You may accept "move away" as an answer. The question does not require an answer in terms of wavelength specifically.