Hardness of a material indicates its resistance to: (a) flow of electrons (b) flow of heat (e) penetration by magnetic field (d) elastic and plastic deformation (e) penetration by nuclear radiation

The temperature of air decreases as it is compressed by an adiabatic compressor. a)- true b)- false

Ariver flows from north to south at 8 km/h. a boat is to cross this river from west to east at a speed of 20 km/h (speed of the boat with respect to the earth/ground). at what angle (in degrees) must the boat be pointed upstream such that it will proceed directly across the river (hint: find the speed of the boat with respect to water/river)? a 288 b. 21.8 c. 326 d. 30.2

Which of the following controllers anticipates the future from the slope of errors over time? a)-proportional b)-on/off c)-integral d)-derivative.