Kpl.12

12-1
a)
$E_k=\frac{1}{2}mv^2=\frac{1}{2}\cdot60kg\cdot\left(\frac{6}{3{,}6}\right)^2\frac{m}{s}=83J$
b)
$E_k=\frac{1}{2}mv^2=\frac{1}{2}\cdot11kg\cdot\left(\frac{100}{3{,}6}\right)^2\ \frac{m}{S}=4243{,}82...\approx4{,}2kJ$

12-2
$E_{k{,}auto}=\frac{1}{2}mv^2=\frac{1}{2}\cdot1250kg\cdot\left(\frac{90{,}0}{3{,}6}\right)^2\ \frac{m}{s}=390625J$

$E_{k{,}rekka}=E_{k{,}auto}$

$\frac{1}{2}m_{rekka}v_{rekka}^2=E_{k{,}auto}$
$v_{rekka}=\sqrt[]{\frac{E_{k{,}auto}}{\frac{1}{2}m_{rekka}}}$
$v_{rekka}=x$

$x=\sqrt[]{\frac{390625J}{\frac{1}{2}\cdot40000kg}}=4{,}4194...\ \frac{m}{s}=15{,}909...\approx16\frac{km}{h}$

12-5
12-9