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A toy car is moving along with 0.40 J of kinetic energy. If thespeed is doubled, what will the new kinetic energy be?

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Given the Kinetic energy of a toy car, K.E.=04.J

To find new Kinetic energy, K.E.' when speed is doubled.

Kinetic energy is given by the formula,


K\mathrm{}E\mathrm{}=(1)/(2)mv^2

Here, m is the mass and v is the speed.

Now, if the new speed v'=2v, then new kinetic energy will be


\begin{gathered} KE^(\prime)=(1)/(2)mv^(\prime2) \\ \end{gathered}


\begin{gathered} K\mathrm{}E\mathrm{}^(\prime)=(1)/(2)m(2v)^2 \\ =(1)/(2)m*4v^2 \\ =4*(1)/(2)mv^2 \\ =4* K.E. \end{gathered}

Substituting the value of K.E. in the above equation, we get


\begin{gathered} K\mathrm{}E\mathrm{}^(\prime)=4*0.4 \\ =1.6\text{ J} \end{gathered}

Thus, the new kinetic energy will be 4 times of initial kinetic energy and its value will be 1.6 J when speed is doubled.

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