Do you love to have fun in the water? On a hot summer day, a dip in a cool pool, lake or river can be delightful.

Others enjoy feeling the wind in their hair as they speed along the surface of the water. Have you ever ridden in a speed boat? It can be a thrilling experience to bump along the tops of the waves and feel the spray of the water.

But what about an even more personal experience riding the waves? What if you could ride a bike or a motorcycle on the water? Wouldn't that be cool? Well, you can come close to that sensation, if you want. All you need is a personal water craft!

You may know these exciting water machines by one of their most popular brand names: Jet Ski®. Personal water craft (PWC) can be found on lakes, rivers and oceans all over the world. Since the late 1960s, these small, fast, personal boats have become extremely popular.

Most regular boats boast large motors that rapidly spin a propeller to move the boat forward. Personal water craft, on the other hand, contain engines that are similar to jet engines in planes. Instead of turning a propeller, personal water craft engines push the craft forward by squirting a powerful jet of water behind the craft.

How does that work? Is it magic? No! It's science, pure and simple. Specifically, it's Isaac Newton's third law of motion at work. You may have heard Newton's third law of motion stated something like this: “every action has an equal but opposite reaction."

Although that might sound confusing, it's easy to understand if you think of a practical example. If you want to move forward on a skateboard, which direction do you push? Forward? No! You push backward. That action (pushing backward) has an equal but opposite reaction (you move forward).

Personal water craft work on this same principle. The engine powers a pump, called an impeller, which sucks in water and blasts it out of a hole in the back of the vehicle. The force of the water pushing backward drives the craft forward.

Because personal water craft — and their passengers — weigh more than the water being pushed out the back of the craft, they need powerful engines that can push the water out fast enough to create enough force to move the craft forward quickly. That's why many personal water craft have engines that are as large as the engines you might find in a small car or large motorcycle!

Although Isaac Newton figured out the science behind personal water craft hundreds of years ago, modern personal water craft weren't invented until the late 1960s. Clayton J. Jacobson is usually given credit for its invention, although many of the important pieces of modern personal water craft, including the impeller and fiberglass body, were already in existence.

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Tomorrow’s Wonder of the Day is a nautical disaster!