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Newton’s 1 st Law

Newton’s 1 st Law. November 27. Mrs. Brown. Newton’s First Law : Objects at Rest stay at rest, objects in motion, stay in motion until acted on by an unbalanced force. Warm - Up: Write Newton’s First Law in your journal. Today’s Agenda: Complete Warm-Up Review Explore Newton’s Laws

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Newton’s 1 st Law

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  1. Newton’s 1st Law November 27 Mrs. Brown Newton’s First Law: Objects at Rest stay at rest, objects in motion, stay in motion until acted on by an unbalanced force. • Warm - Up: • Write Newton’s First Law in your journal. • Today’s Agenda: • Complete Warm-Up • Review • Explore Newton’s Laws • In-Depth – Newton’s 1st Law

  2. What is the Net Force?

  3. If the piano is pushed for 20 meters, how much work is done?

  4. 200 N 85 N What is the Net Force?

  5. Balanced Force Equal forces in opposite directions produce no motion Explain why the forces are balanced.

  6. Unbalanced Forces Unequal opposing forces produce an unbalanced force causing motion What is the magnitude of forces on the truck?

  7. Background Sir Isaac Newton (1643-1727) He was an English scientist and mathematician famous for his contributions to our understanding of motion and gravity.

  8. Newton’s First LawINERTIA 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.

  9. Newton’s First Law (Law of Inertia) • INERTIA is the tendancy of an object to ______________ in the motion of the object • more _____ means more ______ resist CHANGE mass Inertia

  10. INERTIA more MASS means more INERTIA

  11. Objects at rest, tend to stay at rest… … until acted on by an unbalanced force!

  12. Newton’s First Law is also called the Law of Inertia Inertia: the tendency of an object to resist changes in its state of motion

  13. Inertia Objects in motion, tend to stay in motion… … until acted on by an unbalanced force.

  14. If objects in motion tend to stay in motion, why don’t moving objects keep moving forever? Things don’t keep moving forever because there’s almost always an unbalanced force acting upon them. A book sliding across a table slows down and stops because of the force of friction. If you throw a ball upwards it will eventually slow down and fall because of the force of gravity.

  15. In outer space, away from gravity and any sources of friction, a rocket ship launched with a certain speed and direction would keep going in that same direction and at that same speed forever.

  16. What is this unbalanced force that acts on an object in motion? • There are four main types of friction: Friction! • Sliding friction: ice skating • Rolling friction: bowling • Fluid friction (air or liquid): air or water resistance • Static friction: initial friction when moving an object

  17. Quiz- Which Has More Inertia?

  18. Examples of Inertia • Headrests are placed in cars to prevent whiplash injuries during rear-end collisions. • While riding a skateboard (or wagon or bicycle), you fly forward off the board when hitting a curb, a rock or another object which abruptly halts the motion of the skateboard. Inertia… it will get you every time. Watch where you’re going.

  19. More Examples from Real Life A powerful locomotive begins to pull a long line of boxcars that were sitting at rest. Since the boxcars are so massive, they have a great deal of inertia and it takes a large force to change their motion. Once they are moving, it takes a large force to stop them. On your way to school, a bug flies into your windshield. Since the bug is so small, it has very little inertia and exerts a very small force on your car (so small that you don’t even feel it).

  20. Newton’s First Law Activity 1: Egg Drop Activity 2: Crazy Coin Trick Activity 3: Coin-In-A-Cup Activity 4: “Bombing the Basket” Activity 5: Tablecloth Trick Activity 6: Broken Nose or Whiplash?

  21. Exit Slip: In your own words write the First Law of Motion. Draw a picture that demonstrates the 1st Law of Motion.

  22. Newton’s 1st Law November 28 Mrs. Brown Reminders: FINISH DISCUSSION QUESTIONS on the BACK of LAB SHEET for HOMEWORK!!! • Warm - Up: • How does Newton’s First Law apply to the picture to the right? • Today’s Agenda: • Complete Warm-Up • Review Net Force • Explore Newton’s Laws of Inertia Lab • 5. Homework – finish last page of Lab

  23. Warm Up: How is Newton’s 1st Law demonstrated in the picture below?

  24. How does this represent the Law of Inertia?

  25. The graph probably depicts -- • A jogger running at a constant speed in the park • A child skipping for 15 meters then walking for 20 meters • A car driving at a constant speed, stopping at a red light, then continuing at a constant speed • D. A student sitting in a desk What is the average speed of the object in the graph?

  26. What was Michael’s average speed? Which graph best shows Michael’s motion? Speed Distance Distance Time Time Time

  27. What is the Net Force on the Object? 20 N 10 N If the object is moved for 100 cm, how much work was done?

  28. What is the net force?

  29. Describe the forces?

  30. Newton’s First LawINERTIA 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.

  31. Newton’s First Law (Law of Inertia) • INERTIA is the tendancy of an object to ______________ in the motion of the object • more _____ means more ______ resist CHANGE mass Inertia

  32. INERTIA more MASS means more INERTIA

  33. Objects at rest, tend to stay at rest… … until acted on by an unbalanced force!

  34. Inertia Objects in motion, tend to stay in motion… … until acted on by an unbalanced force.

  35. If objects in motion tend to stay in motion, why don’t moving objects keep moving forever?

  36. What is this unbalanced force that acts on an object in motion? • There are four main types of friction: Friction! • Sliding friction: ice skating • Rolling friction: bowling • Fluid friction (air or liquid): air or water resistance • Static friction: initial friction when moving an object

  37. Newton’s First Law Activity 1: Egg Drop Activity 2: Crazy Coin Trick Activity 3: Coin-In-A-Cup Activity 4: “Bombing the Basket” Activity 5: Tablecloth Trick Activity 6: Broken Nose or Whiplash?

  38. Newton’s 2nd Law November 29 Mrs. Brown Reminders: Projects Due December 17!! • Warm - Up: • In your journal write - “Newton’s Law of Inertia would apply at a grocery store when….” • Today’s Agenda: • Turn in Homework • Demonstration of Newton’s 2nd Law of Motion Some fun demonstrations of the Law of Inertia.

  39. Explain Newton’s First Law in your own words.

  40. How does this demonstrate Newton’s First Law?

  41. Newton’s Law of Force Acceleration: any change in velocity…. ___________, ____________ or ___________ Slows down turns Speeds up

  42. Newton’s Law of Force F = ma To find MASS, you would ___________ force by acceleration. To find ACCELERATION, you would _____________ force by mass. F DIVIDE a m DIVIDE

  43. The more mass an object has, the more ________ required to cause it to accelerate. FORCE

  44. What does F = ma say? that the mass or the speed of an object determines the amount of force required to move it. Something very massive that’s moving very slowly, like a glacier, can still have great force. Something very small that’s moving very quickly, like a bullet, can still have a great force.

  45. Mass affect Acceleration Force affects acceleration Mass Force

  46. If an equal amount of force is applied to the two cars above, the heavier car will accelerate _____________. MORE SLOWLY

  47. A bowling ball and a soccer ball are both pushed with 1kN of force, why does the soccer ball accelerate more?

  48. Can you see the relationship between force, mass and acceleration? Explain.

  49. Newton’s Second Law Acceleration: any change in velocity. If the dog increases the force, the acceleration will __. If the mass of the rock increases, the acceleration will __.

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