Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected] everyone on Earth sat down in the ocean, how far would the water rise? – Zahkaev and ViktorHypothetical questions, like what would happen if everyone on Earth went for an ocean swim at once, are fun to think about. And using math, you can get pretty close to a real answer. Let’s start by considering a smaller version of the same question.Bathtub mathIf you fill a bathtub all the way to the top and hop in, you know you’re in for a soggy cleanup. The water overflows because your body pushes it out of the way – something called displacement. Since the tub has a solid bottom and sides, the only direction the water can go is up and out.AdvertisementAdvertisementThe amount of space an object – in this case, you – takes up is called volume. The volume of water that overflows the tub is equal to the volume of your body.Now think about a situation where the bathtub is only half full. As you hop in, the volume of your body still pushes the water up. You can calculate how much the water level in the tub will rise with a few simple math equations.Suppose the bathtub is a rectangular box. You can figure out how much the water level will rise when you sit down in the tub by considering how much volume you are adding to the tub and what size area you are spreading this volume over. The amount the water level rises is equal to the added volume divided by the area.For a bathtub that is 5 feet long and 2 feet wide, the area is 10 square feet.AdvertisementAdvertisementNow, let’s figure out your volume. To make the math easier, let’s suppose that you, like the bathtub, are also a rectangular box. Let’s say you are about 4 feet tall and 2 feet wide (from left to right) and 1 foot deep (from front to back). The volume of your body would be 4 feet x 2 feet x 1 foot, or 8 cubic feet.When you sit down, you are adding the …
