Q. 54 If the Taylor's tool life exponent n is 0.2, and the tool changing time is 1.5 min, then the tool life (in min) for maximum production rate is Q. 55 An aluminium alloy (density 2600 kg/m) casting is to be produced. A cylindrical hole of 100 mm diameter and 100 mm length is made in the casting using sand core (density 1600 kg/m). The net buoyancy force (in newton) acting on the core is