Regardless of their frequency, wavelength, or energy, all electromagnetic waves: a. travel only through the vacuum of space. b. are a part of what is called "visible light." c. emit radiation that is harmful to humans. d. travel with the same speed in a vacuum.

Two horses begin at rest. after a few seconds, horse a is traveling with a velocity of 10 m/s west, while horse b is traveling with a velocity of 13 m/s west. which horse had a greater acceleration? a. horse a because its change in velocity was greater than horse b's in the same time. b. horse b because its change in velocity was greater than horse a's in the same time. c. horse b because its change in velocity was the same as horse a's, but it took less time. d. both horses had the same acceleration.