1. Determine the mass (in kg and in Ibm) and the weight (N and lbf) of the air contained in a room whose dimensions are 6 mx 6 mx 8 m. Assume the density of the air is 1.16 kg/m3.
Knowing that the acceleration of gravity g=9.81 m/s = 62.2 ft2/s.

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

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

What is the heat treatment of metals? what is the benefit of it? why and how it's useful? answer in details, do not write by hand.