March 16 2009 What do you know about
March 16, 2009 What do you know about gravity? (at least 2 things!) After you complete the bellringer: Answer the questions on the Pre Test on the worksheet
Goals • To define gravity • To interpret situations using the Universal Law of Gravity.
Q: What’s Gravity? • Gravity is the attraction of one object to another • Attraction occurs when molecules of one object pull on molecules of another object • Gravity pulls things together, toward the center (it does not act DOWN!)
Q: What kinds of objects have gravity? • Anything with mass has gravitational pull/force • You have gravity, so why don’t you notice your own gravity? – Your gravity is VERY small compared to that of the Earth, so you notice the Earth’s gravity but not your own.
Q: Who discovered gravity? • Issac Newton played a big part (remember his apple falling from a tree? ) He probably thought: the apple is speeding up as it moves toward the ground, so there must be a force acting on it (Remember his 2 nd law? F = ma) Let’s call the force gravity, and the associated acceleration “acceleration due to gravity”
Q: Who discovered gravity? • This force reaches all the way to the moon, keeping the moon in orbit!
Q: Who discovered gravity? • Universal Law of Gravitation – All objects in universe experience gravitational attraction (hence UNIVERSAL!) – Newton is famous for observing the universality of gravity
NO HOMEWORK!
- Slides: 8