3. The figure below shows a ciraular steel plate supported on three posts A, B and C which are equally spaced along its circumference. A load W= 1350 N is at a distance x= 0.5 m from the post at A along the x-axis. The diameter of steel plate is 1.8 m. a) Determine the reaction at post A. Neglect weight of the steel plate. b) Determine the reaction at post B. Neglect weight of the steel plate. c) Compute the reaction at c, considering the weight of plate, if it has a thickness of 16 mm and has a unit weight of 77 kN/m³. Diameter = 1-8m %3D A

A circular log floating in water is neutrally buoyant. Our ancestors found that by having half a log with semi-circular cross section and hollowing out the interior, it became stable so that they could use it to migrate across oceans. The reasons for it to become stable are: (i) (ii) (iii) (iv) It lowers the centre of gravity G so that it is below the centre of buoyancy B. It lowers the centre of gravity G so that it is below the metacentre M. It increases the metacentric radius BM. It enables the shifting of the centre of buoyancy B laterally to produce a restoring moment when it is tilted. (A) (B) (C) (D) (i) and (ii) (ii) and (iii) (iii) and (iv) (iv) and (i)

Describe the various forms of the first-law relation for closed systems.

Drop-load (I)This exercise is part of a series of problems aimed at modelling a situation by progressively refining our model to consider more and more parameters. This progressive approach is very close to what professional scientists do! Context We want to lower a suspended load in a controlled way so that it hits the ground with a speed whose modulus is not too great. To do this, the suspended load (B) is connected by a rope passing through a pulley to another mass (A), which can move on a horizontal surface. Information The masses of the charges A and B are known.The pulley is a ring of mass mp and radius R that can rotate without friction.The surface on which mass A is placed is horizontal.There is no friction between mass A and the surface on which it is placed.The string attached to mass A is perfectly parallel to the surface on which the mass rests. SchematizationDraw a diagram of each object that interests us. Draw x- and y-axes for each object. Draw and name each force…