91影视

A system is a collection of related items that act together as pieces of an integrated network or process.

Since$\mathrm{A},\mathrm{B}$, and $\mathrm{C}$are defined as distinct systems, add $螖K$for each system to get the total. If $\mathrm{A}$is stationary then its $K$does not change. Therefore,

$螖K_{\mathrm{A}}=0$

According to the work energy theorem, the force of A on B increases $K_{\mathrm{B}}$by $10\mathrm{J}$and the forces due to environment increase it by $4\mathrm{J}$. Therefore,

$螖K_{\mathrm{B}}=10\mathrm{J}+4\mathrm{J}$

$=14\mathrm{J}$

The force of A on C decreases its kinetic energy by $5\mathrm{J}$and the forces due to the environment increase it by $8\mathrm{J}$. Therefore,

$螖K_{\mathrm{C}}=8\mathbf{J}-5\mathrm{J}$

$=3\mathrm{J}$

The sum of all these change in energy is calculated as follows,

$螖K_{\text{weal}}=螖K_{\mathrm{A}}+螖K_{\mathrm{B}}+螖K_{\mathrm{c}}$

$=0\mathrm{J}+14\mathrm{J}+3\mathrm{J}$

$=17\mathrm{J}$

All of the effort is done to change the kinetic energy of the individual systems because all of the forces are external to the system.

As a result, A, B, and C have the same internal energy.

Therefore,

All of the effort is done to change the kinetic energy of the individual systems because all of the forces are external to the system.

As a result, A, B, and C have the same internal energy.

Therefore,

$螖U_{\text{internal}}=0$

Therefore, total change in kinetic energy is $螖K_{\text{wotal}}=17\mathrm{J}$and $螖U_{\text{intemal}}=0$.

When all three items are considered as one system, the interaction energy increases owing to object interaction. $\mathrm{A}$$onBandC$. Therefore, change in total internal energy is calculated as follows,

$螖U_{\text{intemal}}=10\mathrm{J}-5\mathrm{J}$

$=5\mathrm{J}$

In this case, the kinetic energy is increased by the work done by external forces (environment).

Therefore,

$螖K_{\text{lotal}}=8\mathrm{J}+4\mathrm{J}$

$=12\mathrm{J}$

Hence, the change in total kinetic energy and internal energy is $螖K_{\text{total}}=12\mathrm{J}$and

$螖U_{\text{intemal}}=5\mathrm{J}$respectively.