IES Grant Module Format. Module 15- Gravity

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1 IES Grant Module Format Grade Level- 8th Module 15- Gravity PA State Standard (# & short description) S6.C.3.1.2: Explain why gravitational force depends on how much mass the objects have and the distance between them. S8.C.3.1.1: Describe forces acting on objects (e.g., friction, gravity, balanced versus unbalanced). Module Objective(s) Students will be able to define the force of gravity Picture Prompts- Gravity Slide Show Essential Question(s) Module #15 1. Do Now: Pre-test (10 minutes) 2. Video Clip: 3. Vocabulary: Gravity- that gravity is the tendency of objects with mass to accelerate towards each other The raindrops fell to the ground because of gravity Mass- is a physical property of matter that explains how much matter is in an object The bowling ball had a greater mass than the basketball

2 Weight- is a force which is calculated by multiplying the acceleration of gravity times mass. My weight is greater on Jupiter because Jupiter has a larger mass than the Earth Sir Isaac Newton- Sir Isaac Newton lived from He is known as one of the greatest scientists that ever lived. Force- A push or pull on matter Gravity is a force that pulls things toward the ground 4. Lecture Part 1: Isaac Newton. You have heard of him right? His name seems to keep coming up when we talk about motion, and force, and today...gravity. Sir Isaac Newton lived from He is known as one of the greatest scientists that ever lived. The story says Isaac Newton was sitting under an apple tree when an apple fell on his head. He was curious as to why this happened. So Isaac Newton did his thing and researched gravity. What is gravity? You need to know that gravity is the tendency of objects with mass to accelerate towards each other. That s pretty crazy. And what does that mean? Listen to this lecture and you ll find out. We have all experienced gravity here on Earth. Gravity is actually a universal law, that means it occurs everywhere in the universe. Gravity affects all things, both on Earth as well

3 as in the universe. All objects are attracted to each other due to the force of gravity. But lets worry about us right now on Earth. You are probably sitting in your chair right now, which is sitting on the floor, because of gravity. Here is another example, when I drop this ball what s going to happen? It s going to fall right? Of course. It falls because of gravity! Gravity is one of the forces in nature. Gravity is based on two things. Write this down, gravity is based on mass And the distance it is from another object. Because the Sun is so massive (has so much mass), the Sun s gravity is what holds our Earth and the other planets in our solar system together, even though the Earth is so far away (93 millions miles away). Since Jupiter is the largest planet (by mass), it has the most gravity of all the planets. Pluto because of its small mass, has the least amount of gravity of all the planets. So therefore we can understand that gravity is greater when the mass is larger. Gravity is also greater when the distance is shorter. That is why we, as humans, stick to the Earth instead of get pulled to Sun, because we are really close to the Earth- right, we are on it right now. (and even on the Earth, you actually weigh less on top of a tall mountain than at sea level- because we are further away from the center of the earth, pretty cool huh.) So we mentioned Mass? What is mass? Note this, Mass is a physical property of matter that explains how much matter is in an object. Basically mass is the amount of stuff in an

4 object. Which has more mass, a bowling ball or a basketball? A bowling ball right, its full of bowling ball stuff, where a basketball if full of air. The mass an object has, the more gravity is has. Because mass is the amount of matter in an object, the mass does not change when gravity changes. So even if you could stand on our massive sun, you would still have the same mass. Mass doesnt change. How about weight? We all have weight as well. We measure weight by stepping on the scale, by doing that we are measuring how much gravity is pulling you down. That how a scale works. Write this down- Weight is a force which is calculated by multiplying the acceleration of gravity times mass. So when we say we want to lose weight, we really mean we want to lose mass. Add this to your notes- Weight can change when gravity changes. An elephant on the Earth would weigh less on the Moon, because gravity is less on the moon. An elephant s mass would not change if he went to the moon. In your homework reading tonight you will see approximately how much you would weigh if you could visit different planets. Your mass remains the same, but your weight would change due to the mass of the planet you visit. Lets review. Isaac Newton studied gravity. Gravity is a force that pulls objects towards the Earth. Gravity depends on mass and distance. The more massive an object, the more gravity. The close you are to an object the greater the force

5 of gravity. Gravity affects all things on Earth and in the universe. This ends our module on gravity. 5. Activity: Gravity Activity- drop different size and shape objects- watch them fall. Discuss gravity (discuss wind resistance). 6. Review Notes: Address Note-taking students, Go to the last page of your notes and write five lecture points, you may refer to your notes, Address all other students, Fill in any gaps in your notes. 7. Post Test: 8. Homework/Follow-up: Gravity Reading