PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
While practicing free kicks, a soccer player launches a ball from ground level so that it lands on level ground at the same height from which it was kicked. Air resistance is negligible.
(a) Describe how the horizontal component of the ball’s velocity changes, if at all, during the flight. Support your answer with reasoning based on forces acting on the ball.
(b) Explain why the magnitude of the ball’s velocity just before it lands equals the magnitude of its initial velocity.
(c) Compare the time it takes for the ball to rise from launch to its highest point with the time it takes to fall from its highest point back to the ground. Justify your comparison in terms of appropriate kinematic quantities.
(d) The player repeats the kick with a larger initial speed but maintains the same launch angle. Explain qualitatively how the time of flight changes, if at all, and cite the relevant kinematic relationships in your argument.