Question

Safawi kicked a ball with an initial speed of 20 ms-1 at 30º angle. If the ball experienced a constant vertical acceleration of -9.81 ms-2, calculate the ball’s maximum height and distance. Explain how soccer player could apply the force of summation theory to optimize his kicks performance.  

Answer 1

Explanation & Calculations

• Apply $\uparrow\,v^2 = u^2+2as$ to calculate the max height.

$\qquad\qquad \begin{aligned} \small 0^2&=\small (20\sin30\,ms^{-1})^2+2(-9.81\,ms^{-1}\times h)\\ \small h&=\small 5.1\,m \end{aligned}$

• Apply $\small s = \frac{u^2}{2g}\sin 2\theta$ horizontally to calculate the distance.

• The player moves the dominant leg bent at first and extends it just before hitting the ball.
• For this to happen good, the leg should be bent sufficiently.
• The bent leg is easier to move around the hip than the extended leg.

• The opposite hand on the other side needs to be kept fully extended while the leg is bent and hatched while the leg is fully extended.