In this question use g=9.8g = 9.8g=9.8 m s−2^{-2}−2.
A uniform plank AB AB\,AB of length 6 m and mass 30 kg rests horizontally on two supports at C C\,C and DDD, where AC=1AC = 1AC=1 m and AD=4AD = 4AD=4 m.
A block of mass m m\,m kg is placed on the plank at BBB, and the plank is then on the point of tilting about DDD.
Explain why the reaction of the support on the plank at C C\,C is zero.
Find the value of mmm.
Find the magnitude of the reaction of the support on the plank at DDD.
56 exam-style questions on CCEA A Level Maths 4.2 Moments (A-level only), covering 4.2.1 Moments (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.