An insulated piston-cylinder device initially contains 300 L of air at 120 kPa and 300 K. The air is heated for 15 minutes by a 200 Watt resistance heater inside the cylinder. The air pressure is kept constant during the heating process. Find the entropy change of the air (kJ/oK) using a) the air tables and b) an appropriate constant value of specific heat.

Coiled springs ought to be very strong and stiff. si3n4 is a strong, stiff material. would you select this material for a spring? explain.

Afluid flows with a velocity field given by v=(x/t)i.. determine the local and convective accelerations when x=3 and t=1.

Asolid cylinder is concentric with a straight pipe. the cylinder is 0.5 m long and has an outside diameter of 8 cm. the pipe has an inside diameter of 8.5 cm. the annulus between the cylinder ad the pipe contains stationary oil. the oil has a specific gravity of 0.92 and a kinematic viscosity of 5.57 x 10-4 m2/s. most nearly, what is the force needed to move the cylinder along the pipe at a constant velocity of 1 m/s?