An object is held at an unknown height above Earth’s surface, where the acceleration due to gravity of the object is considered to be constant. After the object is released from rest, a student must determine the object’s speed the instant the object makes contact with the ground.
Which of the following equations could the student use to determine the object’s speed by using the fewest measuring tools if the student does not have access to a motion sensor? Select two answers.

A) vₓ =vₓ₀ +aₓ t
B) x= x₀ + vₓ₀ t + (1/2)aₓt²
C) v²x=v² x₀+2aₓ (x−x₀ )
D) v¯=(x−x₀) /t