Answer:
[tex]9\:\mathrm{J}[/tex]
Explanation:
Kinetic energy is given by the following equation:
[tex]KE=\frac{1}{2}mv^2[/tex], where [tex]m[/tex] is mass in [tex]\mathrm{kg}[/tex] and [tex]v[/tex] is velocity in [tex]\mathrm{m/s}[/tex].
Since the cell phone's mass is given in grams, we need to convert this into kilograms:
[tex]80\:\mathrm{g}\cdot \frac{1\:\mathrm{kg}}{1000\:\mathrm{g}}=0.08\:\mathrm{kg}[/tex].
Therefore, the kinetic energy of the cell phone is:
[tex]KE=\frac{1}{2}\cdot 0.08\cdot 15^2=\fbox{$9\:\mathrm{J}$}[/tex].
