Безопасно ли отключать ноутбук во время его работы, а затем подключить его обратно?

Am I damaging my Hewlett-Packard laptop by leaving it running, unplugging it from an outlet, then walking a few feet to the next outlet and plugging it back in? My brother-in-law says that I am.

No, it should be fine. Laptops are designed to switch between battery and main power.

Stuff to watch out for? Tripping hazards. While barrel connectors are fairly robust, they have been known to fail, especially with a sideways “impact” force. Completely unplugging the power connector would mitigate both this and the risk of tripping. There are special mechanisms for laptop HDDs that park the head in case you drop it.

In essence, anything that can kill a laptop while moving it would kill it anyway. I have had a few desktop divas experience the same failure modes, so it is not especially dangerous to move a laptop.

Your brother-in-law has an outdated view of how rechargeable batteries work. Older laptops used NiCd batteries, which were susceptible to the memory effect. Their maximum charge could be reduced if they were repeatedly partially discharged and then charged. There were all sorts of attempts to mitigate this, including waiting until the battery was discharged before charging it again. It is debatable whether the memory effect was real or not.

Modern laptops use lithium-ion batteries, which have no such problem. They also have sophisticated hardware and software to monitor the battery, keeping it in good condition and preventing anything a consumer is likely to do from harming it.