Question

a ball is launched at an angle. its location at 1 - s intervals is shown. which phrases describe the changes in horizontal speed ($v_x$) and vertical speed ($v_y$) as the ball moves from a to d? tap to select or deselect answers. select one option from each column. horizontal speed ($v_x$): increases the entire time decreases the entire time first increases, then decreases first decreases, then increases never changes vertical speed ($v_y$): increases the entire time decreases the entire time first increases, then decreases first decreases, then increases never changes

Explanation:

Step1: Analyze horizontal speed

In projectile motion, in the absence of air resistance, the horizontal speed \(v_x\) remains constant. There is no horizontal acceleration (\(a_x = 0\)). So, \(v_x=\text{constant}\), which means it never changes.

Step2: Analyze vertical speed

The vertical motion of the ball is under the influence of gravity (\(a_y=-g=- 9.8\ \text{m/s}^2\)). As the ball moves from \(A\) to \(D\) (going up), the initial vertical velocity \(v_{y0}\) is positive. Using the equation \(v_y = v_{y0}+a_yt\), since \(a_y=-g\) and the ball is moving against gravity (upward), the vertical speed \(v_y\) is decreasing.

Answer:

Horizontal Speed (\(v_x\)): Never changes; Vertical Speed (\(v_y\)): Decreases the entire time