A punch must cut a hole 30mm diameter in a sheet of steel 2mm thick. The ultimate shear stress is 55MPa. Calculate the force required.

Explain the difference laminar and turbulent flow. explain it with the shear stress and the velocity profiles.

Thermal stresses are developed in a metal when its a) initial temperature is changed b) final temperature is changed c) density is changed d) thermal deformation is prevented e) expansion is prevented f) contraction is prevented

Compute the pressure drop of 30°c air flowing with a mean velocity of 8 m/s in a circular sheet-metal duct 300 mm in diameter and 15 m long. use a friction factor, f 0.02, and pair = 1.1644 kg/m a. 37.26 pa b. 25.27 pa n c. 29.34 pa d. 30.52 pa