2. NEXT Chapter 3 Newton’s Law Visit www.worldofteaching.comwww.worldofteaching.com For 100’s of free powerpoints

3. NEXTPREVIOUS Newton’s Laws F Newton’s First Law u Law of Inertia F Newton’s Second Law u F = ma F Newton’s Third Law u Action Reaction F Law of Universal Gravitation

4. NEXTPREVIOUS Mass F …is measured in kilograms. F …is the measure of the inertia of an object. F Inertia is the natural tendency of a body resist changes in motion.

5. NEXTPREVIOUS Force F …the agency of change. F …changes the velocity. F …is a vector quantity. F...measured in Newton’s.

6. NEXTPREVIOUS Newton’s First Law F Law of Inertia F “A body remains at rest or moves in a straight line at a constant speed unless acted upon by a force.”

7. NEXTPREVIOUS Newton’s First Law F No mention of chemical composition F No mention of terrestrial or celestial realms F Force required when object changes motion F Acceleration is the observable consequence of forces acting

8. NEXTPREVIOUS Newton’s Second Law The Sum of the Forces acting on a body is proportional to the acceleration that the body experiences F  aF  a  F = (mass) a

9. NEXTPREVIOUS Net Force

10. NEXTPREVIOUS Newton’s Third Law F Action-Reaction F For every action force there is an equal and opposite reaction force

11. NEXTPREVIOUS The Law of Gravity F Every mass exerts a force of attraction on every other mass. F The math… FG = 6.67  10-11 N·m 2 /kg 2

12. NEXTPREVIOUS Gravity Questions F Did the Moon exert a gravitational force on the Apollo astronauts? F What kind of objects can exert a gravitational force on other objects?

13. NEXTPREVIOUS Gravity Questions F The constant G is a rather small number. What kind of objects can exert strong gravitational forces? F If the distance between two objects in space is doubled, then what happens to the gravitational force between them?

14. NEXTPREVIOUS Weight F The weight of an object F W is the gravitational force acting downward on the object. F F W = m g

15. NEXTPREVIOUS Tension (Tensile Force) F Tension is the force in a string, chain or tendon that is applied tending to stretch it. FFTFFT

16. NEXTPREVIOUS Normal Force F The normal force on an object that is being supported by a surface is the component of the supporting force that is perpendicular to the surface. FFNFFN

17. NEXTPREVIOUS Coefficient of Friction  Kinetic Friction F f =  k F N F Static Friction F f   s F N  In most cases,  k <  s.

18. On to problems...