A level math help.

It should be an expression in terms of the old r - can you post what you have?

Are you doing Edexcel? We've had a lot of resources via the [locked but available to teachers] Emporium.

should i kiss goodbye to an A ? 😂

That's because it's not encouraged at GCSE which is a shame. You get questions in GCSE exams like "if this variable doubles, what happens to this variable?", which should be a very simple proportionality argument but students often struggle or resort to algebra when there's no need.

I would expect a Physics student to be very confident with this kind of argument.

Where does the 4 come from? One question does not mean you don't still have a chance of an A.

from the initial radius squared.

Yep that looks OK now

That's because it's not encouraged at GCSE which is a shame. You get questions in GCSE exams like "if this variable doubles, what happens to this variable?", which should be a very simple proportionality argument but students often struggle or resort to algebra when there's no need.

I would expect a Physics student to be very confident with this kind of argument.

Agreed that it's a shame. Variation is expressed quite rigidly in textbooks, & I fear that most teachers will go along with this.