Direction 63264

A railway car weighing 10 t moves around the Earth at a speed of 10 m/s. Determine the kinetic energy of the car relative to the Earth and relative to another car moving at a speed of 10 m/s relative to the Earth, both in the same direction and the opposite direction.

Correct answer:

E₁ =  500000 J
E₂ =  0 J
E₃ =  2000000 J

Step-by-step explanation:

$$\begin{gathered} m=10\text{t}\to \text{kg}=10\cdot 1000\text{kg}=10000\text{kg} \\ v=10\text{m/s} \\ {E}_1=\frac{1}{2}\cdot m\cdot v^2=\frac{1}{2}\cdot 10000\cdot 10^2=500000\text{J} \end{gathered}$$

$$\begin{gathered} v_2=v-v=10-10=0\text{m/s} \\ {E}_2=\frac{1}{2}\cdot m\cdot v_2^2=\frac{1}{2}\cdot 10000\cdot 0^2=0\text{J} \end{gathered}$$

$$\begin{gathered} v_3=v+v=10+10=20\text{m/s} \\ {E}_3=\frac{1}{2}\cdot m\cdot v_3^2=\frac{1}{2}\cdot 10000\cdot 20^2=2000000\text{J} \end{gathered}$$

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