Final answer:
The velocity of a vertically thrown object is zero at the top of its flight, the direction of velocity changes after the top, and the acceleration due to gravity is constant both up and down.
Step-by-step explanation:
This question pertains to one-dimensional motion of an object under the influence of gravity, often discussed in high school physics. To answer: a) An object thrown straight up has a velocity that becomes zero at the top of its flight. b) Yes, the velocity does change direction; it is upward before reaching maximum height and downward after reaching the top. c) The acceleration due to gravity, represented by the symbol g, remains constant in magnitude and direction throughout the motion; it does not change sign on the way up or on the way down.
The object is undergoing free-fall once it is no longer in contact with any force other than gravity, and the acceleration due to gravity is approximately 9.8 m/s² near the Earth's surface, pointed downward.