1. Ms. Mitchell’s 6th Grade Greenbriar West Elementary 2007-2008 Matter

2. Topics Mass Force –Gravity –Weight –Tides –Our Solar System Energy –Potential Energy –Kinetic Energy Power

3. Mass What is mass? Does a party balloon have more mass than a candy bar? How do you figure out an object’s mass?

4. Force – Key Points What is a force? Why does gravity exert a force on you? If an object is not moving does that mean that there are no forces on it?

5. Forces The cool car is in my driveway. Are there any forces on the car? If so, draw them. driveway

6. Gravitational Force - Questions So what causes a gravitational force? Is there a gravitational force on the moon? –Is it larger or smaller than the gravitational force on the Earth?

7. Universal Law of Gravitation F = m (GM e /R e 2 ) = mg (i.e. weight) –Where F = force on an object with mass, m G = gravitational constant = 6.7 x 10 -11 m 3 /kg*s 2 M e = mass of the Earth = 5.94 x 10 24 kg R e = radius of Earth = 6.38 x 10 6 m g = acceleration due to gravity = 9.81 m/s 2 Circle the terms above that are constants

8. Acceleration Due to Gravity There is a force exerted on an object as the result of the mass of the Earth –Therefore, the object is accelerated (I.e. the speed increases) when released At time = 0 seconds, an object is released with no velocity One second later, it is going 9.81 meters/second Therefore, the acceleration due to gravity is 9.81 meters/second per second which is the same as 9.81 m/s 2

9. Gravitational Force Gravitational force keeps us “stuck” to the Earth!!! We actually pull on the Earth but the Earth is too big to move!!! Earth Person F F F person = F earth How much you weigh depends on your mass and the mass of the planet you are on.

10. Weight vs Mass Weight is a force: W = m g  m = mass and  g = acceleration due to gravity = 9.81 m/s 2 m (kg)W (Newtons) 1098 549 12118 552 18177 547 878 Mass, kg Weight, Newtons 0 2 4 6 8 10 12 14 16 18 20 40 0 20 60 80 100 120 140 160 180 PLOT THE DATA!!

11. Review of Science Terms Constant – _____________________________ Variables – _____________________________ Independent Variable – ___________________ Dependent Variable – ____________________

12. Gravitational Force - Questions Is there a gravitational force on a person standing on the moon? –Is it larger or smaller than the gravitational force on the Earth? –Why?

13. How the Moon Causes Tides Since the water in the oceans are liquid they are pulled out of shape by the moon’s gravitational force –Causes water level to rise thus creating tides (i.e. water seemingly getting deeper and shallower for no apparent reason) Earth Moon Water bulging up

14. Our Solar System The Sun is the center of the solar system –Why is it the center? –Why is it useful to have the Sun as the center? Nine planets orbit the Sun –Inner planets are small and rocky What are they? –Outer planets are large and gaseous (mostly) What are they?

15. Our Solar System Inner Planets –Mercury –Venus –Earth –Mars Which planet is hottest? Which planet is coldest? Does this make sense? Outer Planets –Jupiter –Saturn –Uranus –Neptune –Pluto How do you think Pluto was added to our solar system?

16. Inner Planets The time it takes for a planet to orbit the Sun (i.e. orbital period) is proportional to how far the planet is away from the Sun. –Will it take more or less than a year for Venus to orbit the Sun?

17. Asteroid Belt Asteroids are rocky and metallic objects that orbit the Sun but are too small to be considered planets. –Range in size from pebbles to as large as 1000 km –Sixteen asteroids have a diameter of 240 km or greater. Most asteroids are contained within a main belt that exists between the orbits of Mars and Jupiter. –Some have orbits that cross Earth's path and some have even hit the Earth in times past. Asteroids are material left over from the formation of the solar system…

18. Outer Planets - How do the outer (or Jovian) planets differ from the inner (or terrestrial) planets?

19. Planets By Size !!!!!! Mars is the same mass as Earth but half the size – what does that tell you about the density of Mars? Jupiter weighs more than any other planet – twice as heavy as the nest most massive (Saturn). –On which planet would you weigh the most – or would you weigh the same on every planet?

20. Potential and Kinetic Energy What is energy? What is potential energy? What is kinetic energy?

21. Potential Energy Does the box have any stored energy here?

22. Potential Energy What happens when we let go of the box? If the box is to move show the direction of the box. Label the forces on the box!!!!

23. Work, Energy, and Power Review: Force is a push or a pull –Exerting a force over a distance is WORK For example, pushing the desk across the room is “a lot of work” –ENERGY is the ability to do work For example, a compressed spring has the ability to push some object a distance –POWER is the consumption of energy over time For example, power is consumed when a light bulb is left on for a period of time (light bulb dissipates energy)

24. Quick Review of Science Facts Force - ___________ Work - ___________ ____________________ Energy - __________ ___________________ Power - __________ ___________________ Constant – ___________ ______________________ Variables – ___________ _______________________ Independent Variable – _____________________ Dependent Variable – ___ _______________________