Question

question 4
which of the following statements applies to the motion of a ball rising and then falling in free - fall?
i. the ball has constant acceleration as it moves upward.
ii. the ball has constant acceleration at the top of its path.
iii. the ball has constant acceleration as it moves downward.
o i only
o i and iii
o iii only
o i, ii and iii
question 5
a baseball catcher throws a ball vertically upward and catches it in the same spot as it returns to the mitt. at what point in the balls path does it experience zero velocity and nonzero acceleration at the same time?
o the instant before it arrives in the catchers mitt
o midway on the way up
o at the top of its path
o the instant it leaves the catchers hand

Explanation:

Question 4

Step1: Recall free - fall concept

In free - fall, the only force acting on the ball near the Earth's surface is gravity. The acceleration due to gravity \(g\approx9.8\ m/s^{2}\) (downward) is constant throughout the motion. When the ball moves upward, the acceleration is \(g\) downward (decelerating it), at the top of its path the acceleration is still \(g\) downward (even though the velocity is zero momentarily), and when it moves downward, the acceleration is \(g\) downward (accelerating it). So, statements I, II, and III are all true.

Question 5

Step1: Analyze velocity and acceleration at different points

When the ball is thrown vertically upward, its velocity decreases as it moves up due to the downward - acting gravitational acceleration. At the top of its path, the ball's velocity is zero for an instant. But the acceleration due to gravity is still acting downward, so the acceleration is non - zero (\(a = g\approx9.8\ m/s^{2}\) downward).

Answer:

Question 4: D. I, II, and III
Question 5: C. at the top of its path