Question

To clarify the distinction between speed and velocity, and to review qualitatively one-dimensional kinematics.

A woman stands at the edge of a cliff, holding one ball in each hand. At time t0 t_0 , she throws one ball straight up with speed v0 v_0 and the other straight down, also with speed v0 v_0 .

For the following questions neglect air resistance. Pay particular attention to whether the answer involves "absolute" quantities that have only magnitude (e.g., speed) or quantities that can have either sign (e.g., velocity). Take upward to be the positive direction.

Part A

If the ball that is thrown downward has an acceleration of magnitude a a at the instant of its release (i.e., when there is no longer any force on the ball due to the woman's hand), what is the relationship between a a and g g, the magnitude of the acceleration of gravity?

Answer 1

a = g

Step-by-step explanation:

Once released from the woman's hand, the only force acting on the ball (neglecting air resistance) is gravity, that produces a constant acceleration on the earth surface, g = 9.8 m/s², directed downward, so the acceleration of magnitude a and g are the same, for both balls, the one thrown upward with initial velocity +v₀ and the one thrown downward with initial velocity -v₀.