Watch the video in the link https://youtu. be/B15ZWwXy and explain how the file test can be used to test the hardness of the material
Please help

Acircular aluminum shaft mounted in a journal is shown. the symmetric clearance gap between the shaft and journal is filled with sae 10w-30 oil at t 30°c. the shaft is caused to turn by the attached mass and cord. develop and solve a differential equation for the angular speed of the shaft as a function of time.

Two slings are used to lift a girder of length l and uniform weight per unit length. what is the best position for the slings if the bending moment due to the weight of the girder is to be kept to a minimum?

Oxygen at 300 kpa and 400 k is in a closed system with an initial volume of 0.1 m3. is now compressed in a polytropic process, with exponent of n 1.2, to a temperature of 500 k. calculate: a) the boundary work done during the compression, in kj b) the heat transfer during the compression, in kj