INTRODUCTION 2 ULTIMATE BOUNCE our team steps onto the court It has wall to wall trampolines and you're about to play the ultimate game of dodgeball Grab a ball and get jumping You jump onto the trampoline and push the stretchy fabric down It pushes back launching you high into the air as you throw your ball at the other team Forces are at the heart of the science trampolines behind
What's happening with each bounce Forces and motion are at work Your first jump is the force that gets your motion going and the force of the stretchy trampoline keeps you bouncing Have you ever wondered about a trampoline's bounce Or why the moon keeps circling Earth Curious scientists also ask these kinds of questions They study the world and think about how it works They test their ideas and come up with answers based on their evidence Everything on Earth and beyond feels the effects of forces 5
CHAPTER 1 WHERE DOES MOVEMENT COME FROM ow do you send a basketball flying into a hoop You need to use force The many different kinds of forces are all just a push or a pull Forces can get things moving or make them stop They're the reason we have motion EARLY THOUGHTS ON FORCES AND MOTION Forces have fascinated scientists for centuries Ancient Greek philosopher Aristotle studied forces It takes forces to make a basket but scientists didn't always understand what forces were or how worked they
He hypothesized that an object's motion was caused by its need to find more objects like it Aristotle wondered whether rocks and soil were attracted to each other since they were both made of earth He tested his theory and observed it being confirmed in nature Modern scientists know that rocks fall because of gravity But Aristotle's hypotheses gave later scientists lots of ideas to test Aristotle's early questions started to form our understanding of forces and motion DIFFERENT FORCES Although he was wrong about the cause Aristotle did understand that motion begins with a push or a pull Aristotle thought objects on Earth were made of a combination of four elements water earth air and fire He saw rocks fall to the ground and thought the motion was caused by the rock's need to find more elements earth
