Here's a sneak peak at what's to come in the activity. Slide 4: Why are we learning all this? Well, we are about to do a really fun activity. That means they are both accurate and precise! Figure 1: Projectile motion. And finally, in the bottom right picture, all the shots are close together and hit the bull's-eye.
In the bottom left picture, the shots are all close together, meaning they are precise, but they are not close to the bull's-eye, so they are not accurate. In the top right picture, the shots are closer to the bull's-eye, which means the accuracy is getting better, but they are not close to each other (meaning they are not precise). That means the shots are neither accurate nor precise. In the top left picture, none of the shots are very close to the bull's-eye or to each other. Slide 3: These four pictures help un undertand the concepts of accuracy and precision.
In the picture on the screen, do you think the string that is wrapped around the spoon-shaped part should be really tight or really loose? (Answer: Tight.) If the string is tight, do you think more or less force is applied to the projectile or object? (Answer: More force.) If a projectile is launched from an angle greater than 45º, where will it go? (Answer: It will go higher, but not cover as much horizontal distance.) If the same projectile is launched from an angle less than 45º, where will it go? (Answer: It will not go as high and therefore is pulled to the ground more quickly by gravitational force, and thus, falls short.) Now let's talk about force. Remember this fact because you will need to apply it to the construction of your catapults in the upcoming activity. Slide 2: To make a projectile cover the most horizontal distance possible, it should be launched from a 45º angle. Did you know that they are used to launch planes on aircraft carriers where runway space is limited? Engineers have found many useful and fun modern applications for this ancient technology! But even today, catapults are used for many different purposes. Slide 1: When you hear the word "catapult," you might only think of devices that were used during battles in the Middle Ages. Have students answer questions on the Engineering Fun! Catapult Presentation Notes while going through the slides.) Consider reviewing the following information during the presentation. (Optional: show the attached Engineering Fun! Catapult Presentation. Lesson Background and Concepts for Teachers Following the lesson, challenge students to complete the associated activity Right on Target: Catapult Game to build accurate and precise catapults using simple materials. This means the projectile will go faster and farther. The more force you apply by pulling back the rubber band on the slingshot, the bigger the force applied to the projectile.
If you've ever launched something from a plastic spoon (hopefully not food at your brother or sister!), you might know that if you add more force by pulling the top of the spoon back farther, the projectile goes faster and farther. Think of the simplest type of catapult possible: a plastic spoon. How do you think force affects the speed of the Ping-Pong ball and the distance it travels? (Answer: More force means more speed and more distance.) The more force you apply to a catapult, the more force is applied to the object being launched. If we are trying to hit targets with the catapults, we need to discuss a few science concepts. Let's say we want our catapults to launch Ping-Pong balls at a certain target. These days, catapults are used for a variety of reasons, from toys to even launching planes and jets from aircraft carriers that have limited runway space! Who has heard of catapults? What do they consist of? (They consist of a lever and a wheel-and-axel.) What are catapults used for? (Listen to student ideas and experiences.) Originally catapults were designed for use during battles or wars. Like engineers following the engineering design process, before we begin designing or building, we must research catapults and learn as much as we can about them. We are preparing for an activity we will get to do very soon, during which we will design and build our own catapults. Today we are going to learn all about catapults and the important math and science concepts behind them.
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