Edexcel Unit 1 (IAL): Physics on the Go, WPH01 (24th May 2016)

Could someone explain this?
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Thanks

How to calculate part ii?

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Make the graph an approximate triangle and work out its area, which I think will be the elastic potential energy

Dear friends;
i am a new member of TSR and i really need help. I could not use the raw to ums converter from edexcel website and i want to request for something. Can you plz help me somehow by telling me the minimum raw marks required to get full ums marks in 2016jan physics unit 1 edexcel paper. plz help me i really need to know. the only subject that is frightening me is this unit 1 and i am really scared... so plz my dear friend plz help me. thanks

unit 3 forum was way more active

Need help in this question can anyone tell me what to write the ans thanxPosted from TSR Mobile

As the balloon rises the density of the air decreases (becomes thinner). The upthrust on the balloon is proprional to density, hence upthrust will reduce. The volume of the displaced air increases as the balloon expands. This increases the upthrust on the balloon. However the decrease in density has more of an effect than the increase in volume, hence the upthrust reduces.