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Force and Motion Review
- 1.
- 2. •A force issimply a push or a pull. •All forces have both size and direction.
- 3. Do you remember… •BrainPop: Force video clip
- 4. NET FORCES When twoor more forces are combined!
- 5. Some tips: 1. Forcesin the same direction- add the two forces together. + = 1. Forces in different directions- subtract the two and figure out which direction was the stronger of the two. - =
- 6. Balanced vs. unbalancedforces • Unbalanced: when the net force on an object is not zero. These produce a change in motion. • Balanced: when the net force on an object equals zero. These do NOT produce change in motion.
- 7. What is motion? •Whenan object changes position over time when compared with a reference point we say that the object is in motion.
- 8. Speed • The rateat which an object moves. • Depends on distance traveled and the time it takes to travel that distance.
- 9. Speed Formula Average speed= total distance total time
- 10. Velocity •The speed ofan object in a particular direction ***Don’t confuse this with speed…they don’t mean the same thing!!
- 11. • Velocity mustALWAYS include a direction Ex: an airplane’s velocity might be 600 km/h south
- 12. •Velocity changes asspeed OR direction changes
- 13. Resultant Velocity. •SAME DIRECTION:add the two velocities together. •DIFFERENT DIRECTION: subtract the two velocities.
- 14. Acceleration •The rate atwhich velocity changes. •To change velocity (change speed or direction or BOTH) • BrainPop: Acceleration video clip
- 15. • It isnot just HOW MUCH velocity changes, but it is also HOW FAST it changes. • The faster velocity changes, the greater the acceleration is.
- 16. Acceleration Formula Acceleration= finalvelocity – starting velocity time it takes to change velocity • Velocity is expressed in meters per second (m/s) and time is expressed in seconds (s), so acceleration is expressed in meters per second per second (m/s/s)
- 17. Newton’s Laws ofMotion BrainPop: Newton’s Laws of Motion video clip 1 2 3
- 18. Newton’s First Law (lawof inertia) An object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force. 1
- 19. Balanced Force Equal forcesin opposite directions produce no motion
- 20. Unbalanced Forces Unequal opposingforces produce an unbalanced force causing motion
- 21. Newton’s First Law(law of inertia) • Mass (kg)is the measure of the amount of matter in an object. • INERTIA is a property of an object that describes how much it will resist change to the motion of the object • More mass an object has means more inertia the object will have.
- 22. • There arefour main types of friction: –Sliding friction: ex. ice skating –Rolling friction: ex. bowling –Fluid friction (air or liquid): ex. air or water resistance –Static friction: ex. initial friction when moving an object What is this unbalanced force that acts on an object in motion?
- 23. This will helpup remember: Newton’s First Law video clip
- 24. Newton’s Second Law Forceequals mass times acceleration. 2
- 25. Newton’s Second Law Force= Mass x Acceleration • Force is measured in Newtons • ACCELERATION of GRAVITY Earth) = 9.8 m/s2 • WEIGHT is a measure of the force of gravity on the mass of an object • Weight (force) = mass x gravity (Earth) • BrainPop: Gravity video clip
- 26. This will helpup remember: Newton’s Second Law video clip
- 27. Newton’s Third Law Forevery action there is an equal and opposite reaction. 3
- 28. Newton’s 3rd Law •For every action there is an equal and opposite reaction. Book to earth Table to book
- 29. Think about it. . . What happens if you are standing on a skateboard or a slippery floor and push against a wall? You slide in the opposite direction (away from the wall), because you pushed on the wall but the wall pushed back on you with equal and opposite force. Why does it hurt so much when you stub your toe? When your toe exerts a force on a rock, the rock exerts an equal force back on your toe. The harder you hit your toe against it, the more force the rock exerts back on your toe (and the more your toe hurts).
- 30. Action: earth pullson you Reaction: you pull on earth Action and Reaction on Different Masses Consider you and the earth
- 31. Action: tire pusheson road Reaction: road pushes on tire
- 32. Action: rocket pusheson gases Reaction: gases push on rocket
- 33. This will helpup remember: Newton’s Third Law video clip
- 34. Now its timeto create your own… • You will each be assigned a specific topic within Force and Motion. • You with be responsible for creating a 2-3 minute review video for your topic. Each of you are about to receive the rubric for how your video will be graded. • Using the information you have just reviewed, develop a plan for how you want to present your material. • You will have the rest of the class period to work on this project.
- 35. Don’t forget… • Ifyou need help, you can ask your classmates questions or ask for suggestions using our Facebook page: www.facebook.com/MsAutrysScienceClass