91影视

• Work on the cylinder-rod-earth system is$\mathrm{W}=+100\mathrm{J}$ .

• The gravitational potential energy increase is,$\mathrm{螖笔贰}=20鈥�\mathrm{J}$.
• The kinetic energy increase is, $\mathrm{螖碍贰}=50鈥�\mathrm{J}$.

Here the relation between work done and energy can be used to find change in thermal energy. It is known that the energy can neither be created nor be destroyed but it gets transformed into some other form. In this case that is termed as work done. Here the concept of work done on the system due to all energies - potential energy, kinetic energy, and thermal energy can be used.

Formula:

The work done is given by,

$\mathrm{W}=\mathrm{螖碍贰}+\mathrm{螖笔贰}+{\mathrm{螖贰}}_{\mathrm{th}}$

We have

$\mathrm{W}=\mathrm{螖碍贰}+\mathrm{螖笔贰}+{\mathrm{螖贰}}_{\mathrm{th}}$

As given the work, kinetic and potential energy put in the above equation. we get,

$$\begin{gathered} 100鈥�\mathrm{J}=50鈥�\mathrm{J}+20鈥�\mathrm{J}+{\mathrm{螖贰}}_{\mathrm{th}} \\ {\mathrm{螖贰}}_{\mathrm{th}}=+100鈥�\mathrm{J}-50鈥�\mathrm{J}-20鈥�\mathrm{J} \\ {\mathrm{螖贰}}_{\mathrm{th}}=+30鈥�\mathrm{J} \end{gathered}$$

Therefore, the change${\mathrm{螖贰}}_{\mathrm{th}}$ is$30鈥�\mathrm{J}$ .