how are electromagnetic waves different from mechanical waves?

electromagnetic waves are all high frequency; mechanical waves are all low frequency.

electromagnetic waves can travel through a vacuum; mechanical waves require a medium.

electromagnetic waves are visible; mechanical waves are invisible.

electromagnetic waves always reflect; mechanical waves always refract.

Ablock of mass 1.5 kg slides down an inclined plane that has an angle of 15. if the inclined plane has no friction and the block starts at a height of 3 m, how much kinetic energy does the block have when it reaches the bottom? acceleration due to gravity is g = 9.8 m/s2. a. 6.8 j b. 50.9 j c. 0 j d. 44.1 j

The ratio of lift to drag l/d for a wing or airfoil is an important aerodynamic parameter, indeed, it is a direct measure of the aerodynamic efficiency of the wing. if a wing is pitched through a range of angle of attack, l/d first increases, then goes through a maximum, and then decreases. consider an infinite wing with an naca 2412 airfoil. estimate the maximum value of l/d. assume that the reynolds number is 9x10^6.

Gasoline comes from petroleum, which is made from ancient living things. petroleum, therefore, contains a type of energy. a. heat b. nuclear c. biological d. chemical potential