Final answer:
The graph depicting the velocity of a rock thrown downward should show a straight line with a negative slope starting from the initial velocity value. The velocity will decrease linearly due to gravity's constant acceleration as the rock falls.
Step-by-step explanation:
Velocity of a Thrown Rock
When a rock is thrown downward from a height, its velocity increases linearly over time due to the acceleration of gravity (assuming air resistance is negligible). The initial downward throw adds to this acceleration, meaning the velocity at which the rock is thrown will affect its speed as it falls. The best graph to show the velocity of the rock would be a straight line starting from the initial velocity at t=0 and decreasing linearly as it falls.
The rock's velocity changes at a constant rate due to gravity (approximately -9.80 m/s² on Earth), irrespective of whether it was thrown up or down initially. If Jake throws the rock downward, the graph starts at a negative velocity (since it's thrown downward), and this velocity becomes more negative over time until it hits the ground.
The concept of free-fall applies to both upward and downward motion, with gravity acting constantly throughout the motion. To calculate the rock's position and velocity at specific times, you would apply the kinematic equations taking into account the initial velocity, the acceleration due to gravity, and the times of interest (1.00 s, 2.00 s, and 3.00 s).