Question

Two positively charged particles $X$ and $Y$ are initially far away from each other and at rest. $X$ begins to move towards $Y$ with some initial velocity. The total momentum and energy of the system are $p$ and $E$.Then:

• A. if $Y$ is fixed, both $p$ and $E$ are conserved.
• B. if $Y$ is fixed, $E$ is conserved, but not $p$.
• C. if both are free, $E$ is conserved, but not $p$.
• D. if both are free to move,$p$ is conserved but not $E$.

Answer 1

Answer: (B)

As we know that total energy is conserved for any system. When $X$ is moving momentum of the system will change. If $Y$ is fixed $E$ is conserved but not momentum.