Question

if v crosses from positive to negative, the object: speeds up always; turns around (changes direction); accelerates upward; stops forever

Explanation:

In the context of velocity (\(v\)) in physics, when velocity crosses from positive to negative, it means the object was moving in one direction (positive velocity) and then starts moving in the opposite direction (negative velocity). This indicates a change in direction, i.e., the object turns around. "Speeds up always" is incorrect as speed depends on acceleration and velocity direction relation. "Accelerates upward" is too specific (direction of acceleration isn't implied here just by velocity sign change). "Stops forever" is wrong as the object changes direction, not stops permanently.

Answer:

B. turns around (changes direction)