Answer:
Ball D. Among the four balls in this picture, ball D is the only one whose kinetic energy is greater than [tex]0[/tex].
Step-by-step explanation:
Consider an object of mass [tex]m[/tex]. If this object is moving at a speed of [tex]v[/tex], the kinetic energy of this object would be:
[tex]\displaystyle \frac{1}{2}\, m \cdot v^{2}[/tex].
The speed [tex]v[/tex] of ball A, B, and C are all [tex]0[/tex]. Hence, the kinetic energy of these three balls would be [tex]0\![/tex].
The speed of ball D is greater than [tex]0[/tex]: [tex]v = 2\; \rm m \cdot s^{-1}[/tex]. The kinetic energy of this ball would be:
[tex]\begin{aligned} {\rm KE} &= \frac{1}{2}\, m \cdot v^{2} \\ &= \frac{1}{2}\times \rm 0.43\; \rm kg \times \left(2\; \rm m \cdot s^{-1}\right)^{2}\\ &= 0.86\; \rm J\end{aligned}[/tex].
Hence, the kinetic energy of ball D is the greatest among the four balls in this picture.
