Respuesta :
Given the mass of the object, m= 8 kg.
Final speed of the object, v = 8 m/s
Initial speed of the object, u = 4 m/s
To find work done required to increase the speed from 4 m/s to 8 m/s
Work done = change in kinetic energy
Kinetic energy initially when speed is 4 m/s is given by
[tex]KE._u=\frac{1}{2}mu^2[/tex]Substituting the values, initial kinetic energy will be
[tex]\begin{gathered} K\mathrm{}E._u=\frac{1}{2}\times8\times4^2 \\ =64\text{ J} \end{gathered}[/tex]Similarly, final kinetic energy will be
[tex]\begin{gathered} K\mathrm{}E._v=\frac{1}{2}mv^2 \\ =\frac{1}{2}\times8\times8^2 \\ =256\text{ J} \end{gathered}[/tex]Work done will be
[tex]\begin{gathered} W=K\mathrm{}E._v-K.E._u \\ =256-64 \\ =192\text{ J} \end{gathered}[/tex]Thus, the required work done is 192 J.
