Today I was working on some Vectors exam questions with my Y13 mechanics class and I came across this question:
I have recreated is incorrect working.
Obviously he had found out when the ship was at the lighthouse, instead of 10km away. I explained this to him and started to explain how he should have tackled this when a sudden realisation angered me.
Now for those if you that didn’t work through the question, here is the actual answer:
This is an impossible answer! If the lighthouse is on the trajectory of the ship and it will hit said lighthouse at t=3 then that would stop the ship! At the very least it would slow it down!!!! In reality it would have to avoid the lighthouse and change trajectory. Meaning the second answer, T=5, would not happen under any circumstances!
My initial thought was: “are they expecting students to spot this and discount the second answer? That’s a bit harsh.”
So I checked the markscheme:
What do you guys think? Is this infuriating or am I just getting get up over nothing? I’d love to hear your views in the comments or via social media.