A frame-by-frame analysis of a slow-motion video shows that a hovering dragonfly takes 7 frames to complete one wing beat. If the video is shot at 240 frames per second, (a) what is the period of the wing beat, and (b) how many wing beats does the dragonfly perform per second?

Lol I just learned this, here's the short
Large doses of X-Rays are known to cause cell damage and cancer, so
X-Ray technicians have to stand behind the shield. Here's the lengthy
This is because the patient would only be exposed to the small dose of radiation once, which is hardly harmful. However, radiographers deal with this all day every day, which could mean that the small doses could add up. This is why they stand behind a lead screen; the small exposure to the X-Rays aren't harmful alone but frequent exposure could begin to damage your cells and lead to potential genetic mutation. If a patient is often in radiography (a long-stay patient for example), they begin to wear lead aprons whilst being X-rayed in order to prevent the risk of harm. Hope I answered correctly.