Respuesta :
New kinetic energy:
If the initial kinetic energy of a car is 0.3 MJ and the speed of the car decreased two times then the new kinetic energy will be 0.075 MJ.
The calculation for kinetic energy:
Step-1:
It is given that the car has a kinetic energy of 0.3 MJ. It is required to find the new kinetic energy when the car's speed decreases two times from its initial speed.
Let the mass of the car is m and the initial speed of the car is v.
It is known that the kinetic energy is calculated as,
[tex]\text{K.E}=\frac{1}{2}\times \text{mass}\times\text{speed}^2[/tex]
Therefore the initial kinetic energy is the car is,
[tex]\text{K.E}_1=\frac{1}{2}\times \text{m}\times\text{v}^2[/tex]
Step-2:
The speed of the car is decreased two times. Thus the speed becomes v/2. Therefore the final kinetic energy is the car is,
[tex]\text{K.E}_2&=\frac{1}{2}\times \text{m}\times(\frac{v}{2})^2\\&=\frac{1}{4}\times\frac{1}{2}\times \text{m}\times\text{v}^2\\&=\frac{1}{4}\times\text{K.E}_1\\&=\frac{1}{4}\times {0.3}\text{ MJ}\\&=0.075 \text{MJ}[/tex]
To know more about kinetic energy, refer to:
https://brainly.com/question/10417121
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