Which of the following is a true statement? a. electromagnetic waves are longitudinal waves. b. electromagnetic waves do not always need a medium to travel. c. electromagnetic waves consist of only changing electric fields. d. electromagnetic waves can vary in speed, wavelength and frequency.

Avalue that describes how heavy an object is and is related to the force of gravity is

Agas contained within a piston-cylinder assembly undergoes three processes in series: process 12: compression with pv= constant from 1 bar and 1 liter to 4 bar. process 23: constant pressure expansion to 1 liter. process 31: constant volume calculate the pressure and volume at each state, and sketch the processes on a p-vdiagram labeled with pressure and volume values at each numbered stat

There are two-speed cameras, one in an are where the speed limit is 30 km/h and another where the speed limit is 50 km/h. in which will there be a smaller time interval between the photographs? explain your answer.