Any change in the speed or direction of motion is called "acceleration". You'll hear "deceleration" used for slowing down but that's not technically correct.
Speed is the time rate of an object moving from one place to another, while velocity is the rate and direction of the object's movement. They are very similar but they don't mean the same thing.
Free fall means rapid fall or a downward motion due to gravity. Sentence example: When Joe was accidentally bumped by Sarah, he was sent towards a free fall down the escalator, leading to a serious injury on his arm and two legs.
Answer:
Transverse waves, because the motion of the wave is perpendicular to the direction of propagation. An S-wave is an example of a transverse wave.
Explanation: