Section A
Q1.
(a)
What is D'Alembert's principle ?
Two weights 800 N and 200 N are connected by a thread and move along a rough horizontal plane under the action of a force of 400 N applied to the 800 N weight as shown in the figure below. The coefficient of friction between the sliding surfaces of the weights and the plane is 0.3. Determine the acceleration of the weights and tension in the thread using D'Alembert's principle. (Take g = 9.81 m/s^2)
(b)
A compound stanchion is made up of two ISMC 250 placed back-to-back as shown in the figure below with a gap between the adjacent flat surfaces. Two 36 cm × 1.2 cm plates are rivetted to the flanges, so as to form a symmetrical box section. Determine the amount of gap if the column is to carry maximum load. Properties of ISMC 250 are :
Area = 38.67 cm2
Maximum Moment of Inertia = 3816.8 cm4
Minimum Moment of Inertia = 219.1 cm4
Distance of the centroid from the back = 2.30 cm