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Do now!

Do now!. Can you read each others “Density questions” that you did for homework?. This lesson – 2.4 Pressure. Relate (without calculation) pressure to force and area. Recall and use the equation P = F/A. Oh no!. YouTube - falling through ice YouTube - Jason Falls Through Ice.

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Do now!

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  1. Do now! Can you read each others “Density questions” that you did for homework?

  2. This lesson – 2.4 Pressure • Relate (without calculation) pressure to force and area. • Recall and use the equation P = F/A

  3. Oh no! YouTube - falling through ice YouTube - Jason Falls Through Ice

  4. Spread the force over a greater area

  5. Camels

  6. Snow shoes Tom

  7. Caterpillar tracks

  8. House foundations

  9. My sofa!

  10. Sharp?

  11. I had a dream

  12. Death?

  13. Drawing pins

  14. Pressure N Pressure = Force Area N/m2 or Pa m2

  15. Pressure F N Pressure = Force Area P A x Can you copy this please? N/m2 or Pa m2

  16. An example A woman of weight 600N has a total shoe area of 150 cm2 and a man of weight 750 N has a total shoe area of 360 cm2. What is the pressure beneath their feet?

  17. An example A woman of weight 600N has a total shoe area of 150 cm2 and a man of weight 750 N has a total shoe area of 360 cm2. What is the pressure beneath their feet? Angelina pressure = force/area = 600/150 = 4 N/cm2 Brad pressure = force/area = 750/360 = 2.1 N/cm2

  18. Bunny Suicides involving pressure

  19. Bunny Suicides involving pressure

  20. Bunny Suicides involving pressure

  21. Bunny Suicides involving pressure

  22. Calculating your own pressure Can you do the calculations carefully and neatly on the graph paper to show your pressure (don’t forget you have two feet!) and stick it in your book

  23. Pressure under a car

  24. Pressure under a car • Mass = 2000kg • Weight = mg = 2000x10 = 20000N • Area = ? • Pressure = ?

  25. U571 • YouTube - Ocean Odyssey - Ocean Pressure • YouTube - Styrofoam cup vs. deep sea • YouTube - U-571 Trailer

  26. Fluid pressure acts in all directions • Copy!

  27. Pressure and depth Pressure increases with depth (P = ρgh)

  28. Let’s try some questions! Page 63, questions 1 to 4.

  29. That’s it! • Let’s remind ourselves of what we have done in this unit.

  30. Newton’s 1st Law If there is no resultant force acting on an object, it will move with constant velocity. (Note the constant velocity could be zero). Remember?

  31. Newton’s 1st law If there are no forces, or the forces are balanced – constant velocity Pushing force friction NO RESULTANT FORCE

  32. Newton’s 2nd law There is a mathematical relationship between the resultant force and acceleration. Resultant force (N) = mass (kg) x acceleration (m/s2) F = ma

  33. An example What will be Mr Porter’s acceleration? Mass of Mr Porter and bike = 100 kg Pushing force (100 N) Friction (60 N)

  34. An example Resultant force = 100 – 60 = 40 N FR = ma 40 = 100a a = 0.4 m/s2 Mass of Mr Porter and bike = 100 kg Pushing force (100 N) Friction (60 N)

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