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Opener. PICK UP A NOTE PACKET FROM THE SIDE COUNTER Describe a force (what does it do? What is it?). Newton’s 1 st Law of Motion. Today I will: Define and distinguish between mass, weight and volume Solve for mass and weight. Chapter 4. What is mass?.

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  1. Opener PICK UP A NOTE PACKET FROM THE SIDE COUNTER Describe a force (what does it do? What is it?)

  2. Newton’s 1st Law of Motion • Today I will: • Define and distinguish between mass, weight and volume • Solve for mass and weight Chapter 4

  3. What is mass? Mass – the amount and type of material present a measurement of inertia; the more mass an object has the more inertia it has Scalar quantity SI units kilogram

  4. Scientific definitions: Mass – the quantity of matter in an object; a measure of the inertia, or “laziness,” that an object exhibits in response to any effort made to start it, stop it, or otherwise change its state of motion

  5. How are mass and volume different? • Mass – the amount and type of material present • Volume – measure of space and is measured in units such as cubic centimeters, cubic meters, and liters • Object may have a large mass but not a large volume • Example: Take two bags of the same volume, fill one with feathers and one with rocks, do they have the same mass…. • NO

  6. Mass is NOT weight!

  7. How are mass and weight different? Mass is the amount and type of material present Weight is a measure of the gravitational force acting on the object and depends on the objects location.

  8. Weight – the force of gravity on an object It is a vector quantity Weight is a force F = ma …..so = m SI units: Newton (N)which is kg*m/s2 1 kg = 2.2 lbs

  9. Find you weight in Newtons! X = your mass (kg) = m = m (-9.8 )

  10. While they are not the same; they are directly proportional to each other Objects with great mass have great weight; objects with little mass have little weight Mass and Weight

  11. Today I will: Define force Identify the different types of forces Mass and weight: Which one is universal and why?

  12. Vocab… • Force – any push or pull

  13. Force A force is a push or pull. An object at rest needs a force to get it moving; a moving object needs a force to change its velocity. The magnitude of a force can be measured using a spring scale.

  14. Forces… • What is a force? • Any push or pull on an object • Forces are vector quantities

  15. Types of Forces Weight – force of gravity on an object; acts directly downward Support or Normal force – force acting upward on an object opposing gravity; acts perpendicular to the surface Tension – name given to the force on ropes, strings or chains

  16. Types of Forces con’t • Friction – • force between materials that touch as they move past each other • caused by irregularities in the surface • When friction is present, some force is required to keep an object moving • Acts in a direction that opposes the objects motion

  17. Galileo Con’t Inertia – objects resistance to change of motion

  18. Today I will: Opener: Explain balanced and unbalanced forces Define equilibrium and net force Explain the relationship between net force and motion Name the 4 types of forces and describe each

  19. Balanced vs Unbalance forces Balanced Forces = all forces acting on the object cancel each other out Unbalanced Forces (external) = the forces acting on an object do not cancel out; there is a resulting force

  20. When forces are balanced: Objects at rest: will remain at rest (a balanced force acting on them) Objects in motion: will keep moving with a constant velocity

  21. When forces are Unbalanced: Objects at rest: will move when an unbalanced force acts on them Objects in motion: moving at a constant velocity will accelerate

  22. To get the object to move you must apply a force!!

  23. Vocab • Net force - the combination of all forces acting on an object • (Net force is the resultant force or the sum of all forces) • Add up all the forces in the x and y direction

  24. Equilibrium – occurs when all the forces add up to zero (so the net force is zero); there are forces acting on the object but they all cancel out • Means objects have a balanced force acting on them (so they are at rest or they are moving with a constant velocity)

  25. What does it mean to say that forces are unbalanced or external? The net force is not zero!

  26. Two Categories of Net force • Net force = 0 • Object is in equilibrium • Object is not moving or moving at a constant velocity • Acceleration = 0 • Net force ≠ 0 • Object is accelerating

  27. CDP (blue packet) Back of 4-1 (4-6) Front of 4-2 Back of 4-3 (rest of packet we will do later)

  28. Today I will: Opener: Determine tension in ropes that are at placed at angles Explain Newton’s First Law of Motion and how it relates to motion and inertia Give an example of Newton’s First Law in action Explain what it means to have a net force of zero. Have out CDP

  29. Concept Check Define net force How does net force relate to motion of the object

  30. Go over homework: CDP (blue packet) Back of 4-1 (4-6) Front of 4-2 Back of 4-3 (rest of packet we will do later)

  31. What happens if the ropes are not straight up and down but are out at an angle?

  32. Back of CDP 4-2 and front of 4-3

  33. Historical Figures • Aristotle (384 – 322 BC) • 2 categories of motion • natural motion – straight up or straight down; didn’t think there was a reason …just thought that is what objects do….objects just fall • Violent motion – imposed motion; result of forces pushing or pulling • Thought that the Earth was the center of everything.

  34. Copernicus (Nicolaus Copernicus February 19, 1473 – May 24, 1543) • Earth and other planets move around the sun • Book published on day of his death

  35. Homework: Bookwork found on pages 56-58 all plug-n-chug

  36. Galileo – (Galileo Galilei February 15, 1564 – January 8, 1642) Big supporter of Copernicus Believed in the theory of the sun centered universe Studied under house arrest Studied the fact that objects all fall at the same rate (sentenced in 1633 – was in his sixties)

  37. Galileo – (Galileo Galilei February 15, 1564 – January 8, 1642) • Galileo looked at how things worked rather than why • Known as the “father of modern day physics”

  38. How did the incline work?

  39. Incline planes… • Turn to page 45 in book…. • Refer to pictures for information

  40. Galileo and Kepler Letters recorded as early as 1597 (Galileo in early thirties)

  41. Excerpt from letter to Kepler: August of 1610 My dear Kepler, I wish that we might laugh at the remarkable stupidity of the common herd. What do you have to say about the principal philosophers of this academy who are filled with the stubbornness of an asp and do not want to look at either the planets, the moon or the telescope, even though I have freely and deliberately offered them the opportunity a thousand times? Truly, just as the asp stops its ears, so do these philosophers shut their eyes to the light of truth."

  42. Complete bookwork: all think and solve

  43. Isaac Newton January 4, 1643 – March 31, 1727 • Newton’s Law of Inertia also called Newton’s First Law • Every object continues in a state of rest, or of motion in a straight line at constant speed, unless it is compelled to change that state by unbalanced forces exerted upon it.

  44. NOTE: Saying in a straight line at a constant speed is the same thing as saying CONSTANT VELOCITY! This means the object is NOT accelerating

  45. Newton’s First Law - video

  46. Punching and Newton’s First Law

  47. Demonstrations Hammer Cup and penny Friction

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