Question

question 3 of 10
you kick a soccer ball straight up into the air with a speed of 21.2 m/s. how long does it take the soccer ball to reach its highest point?
a. 4.8 s
b. 1.5 s
c. 2.2 s
d. 3.1 s

Explanation:

Step1: Identify the kinematic - equation

The kinematic equation $v = v_0+at$ is used. At the highest - point, the final velocity $v = 0$. The initial velocity $v_0 = 21.2$ m/s and the acceleration $a=-g=- 9.8$ m/s² (negative because it acts in the opposite direction of the initial velocity).

Step2: Rearrange the equation for time $t$

From $v = v_0+at$, we can solve for $t$: $t=\frac{v - v_0}{a}$. Substitute $v = 0$, $v_0 = 21.2$ m/s, and $a=-9.8$ m/s² into the formula.
$t=\frac{0 - 21.2}{-9.8}=\frac{-21.2}{-9.8}\approx2.2$ s

Answer:

C. 2.2 s