1. (a) explain why the viscosity of a liquid decreases while that of a gas increases with an increase of temperature. (b) the following data refer to a liquid under shearing action at a constant temperature. determine its dynamic viscosity. du/dy (s-¹) t (n/m²) 0 0 0.2 1 0.4 1.9 0.6 3.1 0.8 4.0 2. a 300 mm wide shaft sleeve moves along a 100 mm diameter shaft at a speed of 0.5 m/s under the application of a force of 250 n in the direction of its motion. if 1000 n of force is applied, what speed will the sleeve attain? assume the temperature of the sleeve to be constant and determine the viscosity of the newtonian fluid in the clearance between the shaft and its sleeve if the radial clearance is estimated to be 0.075 mm. 3. a shaft of 100 mm diameter rotates at 120 rad/s in a bearing 150 mm long. if the radial clearance is 0.2 mm and the absolute viscosity of the lubricant is 0.20 kg/(m s), find the power loss in the bearing. 4. a block of dimensions 300 mm x 300 mm x 300 mm and mass 30 kg slides down a plane inclined at 30° to the horizontal, on which there is a thin film of oil of viscosity 2.3 x 10-³ n s/m². determine the speed of the block if the film thickness is estimated to be 0.03 mm. 5. calculate the capillary effect (in millimetres) in a glass tube of 6 mm diameter when immersed in (i) water and (ii) mercury, both liquids being at 20°c. assume o to be 73 x 10-³ n/m for water and 0.5 n/m for mercury. the contact angles for water and mercury are 0 and 130°, respectively. 6. calculate the internal pressure of a 25 mm diameter soap bubble if the tension in the soap film is 0.5 n/m.
