Suppose that a wireless link layer using a csma-like protocol backs off 1ms on average. a packet’s link and physical layer headers are always set at the same bitrate and take a total of 125us to transmit. if a packet is sent with a link layer payload of 1000 bytes at a bitrate of 1mbps, what overhead do the physical and link layers introduce? calculate overhead as the fraction of the complete packet time taken up by backoff and link/physical layer headers.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

The thermal expansion or contraction of a given metal is a function of the f a)-density b)-initial temperature c)- temperature difference d)- linear coefficient of thermal expansion e)- final temperature f)- original length

The higher the astm grain size number, the finer the gran is. a)-true b)-false