Leaving Cert Higher Level Maths 2020 Question 8

[@OideCKelly]

Part (b) l and x are both decreasing so the rates should be negative.

[@SimpleScienceandMaths]

Yes this has been a point of conversation among maths teachers. It will be interesting when the marking scheme comes out as to what the examiners were expecting but from many conversations I and many others believe that 1m/s is a perfectly fine answer as regardless of whether it is increasing or decreasing it is doing so at 1m/s. I think that all answers of 1m/s, -1m/s and decreasing at 1m/s will be accepted. We will have the marking scheme is a few weeks so we know then.

[@SimpleScienceandMaths]

Marking scheme released today, they were looking for 1m/s but I still think students would have got the marks if they said -1m/s

[@cathallawlor989]

Thanks for this :)

[@SimpleScienceandMaths]

No worries!

[@SimpleScienceandMaths]

Solutions to each question: Question 1: kzbin.info/www/bejne/o3u7aWmdaqh5i6M Question 2: kzbin.info/www/bejne/n3TWaIF-ppKfY7s Question 3: kzbin.info/www/bejne/h2api5Wfeq2hnsU Question 4: kzbin.info/www/bejne/foXZnqqGn96rbZo Question 5: kzbin.info/www/bejne/eHaUo2Zul7mtaac Question 6: kzbin.info/www/bejne/qqe1c3iCo8adqdk Question 7: kzbin.info/www/bejne/n5bXZ2huh7qFaqs Question 8: kzbin.info/www/bejne/aYaYYaGhnJuKr8k Question 9: kzbin.info/www/bejne/fXOaf6aEhsaVrMU

[@maryselkirk9962]

is dl/dt not -1.5?

[@SimpleScienceandMaths]

No this is not necessary. You can of course argue that the shadow is decreasing so it should be -1.5, however the question is asking for the rate of change, it is changing at a rate of 1.5m/s, whether it is increasing or decreasing is not relavent.

[@robwhitty]

dx/dt = dx/dl. dl/dt ?