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Why does the earth “have more gravity,” i.e. g is larger on earth, than does the moon?

Physics 1710 —Warm-up Quiz. Answer Now !. 0. 39% 55 of 140. 0. Why does the earth “have more gravity,” i.e. g is larger on earth, than does the moon?. The earth as an atmosphere. The earth has a larger diameter. The earth has more mass. The earth rotates faster. None of the above.

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Why does the earth “have more gravity,” i.e. g is larger on earth, than does the moon?

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  1. Physics 1710—Warm-up Quiz Answer Now ! 0 39% 55 of 140 0 Why does the earth “have more gravity,” i.e. g is larger on earth, than does the moon? • The earth as an atmosphere. • The earth has a larger diameter. • The earth has more mass. • The earth rotates faster. • None of the above.

  2. Physics 1710—Chapter 14 Fluid Dynamics 0 Analysis: The earth has an atmosphere because of its larger g, not vis versa. The larger diameter means smaller g~1/R2 The larger mass of the earth m = 4/3πρR3 makes a larger g=GM/R2 Gravity has nothing to do with the rate of rotation.

  3. Physics 1710—Chapter 14 Fluid Dynamics 0 Summary: Pressure is the force per unit area. P =F/A Unit of pressue [Pacal] = [N]/[m2] The hydrostatic pressure is P = Po + ρgh Archimedes’ Principle: Fbouyant = ρfluid g V Equation of Continuity: A1v1 = A2v2 Bernoulli’s Equation:P + ½ ρv2 + ρgy = constant.

  4. 0 Physics 1710—Chapter 14 Fluid Dynamics 80/20Pressure = Force per unit Area P = F /A

  5. Physics 1710—Chapter 14 Fluid Dynamics 0 80/20The unit of pressure in SI units is the Pascal [Pa] = 1 Newton/ m2 1 Newton force 1 Pascal pressure: 1 square meter area

  6. Physics 1710—Chapter 14 Fluid Dynamics 0 80/20Standard atmosphere = 1.0 atm =101 kPa =14.7 psi Tire pressure A few 100 kPa

  7. Physics 1710—Chapter 14 Fluid Dynamics 0 Which applies the greatest pressure on their foot?

  8. Physics 1710—Chapter 14 Fluid Dynamics 0 40% 57 of 140 Answer Now ! 0 Which applies the greatest pressure on their foot? • Man. • Elephant. • Woman.

  9. Physics 1710—Chapter 14 Fluid Dynamics 0 Force = 200 lb = 891 N Foot Area = 36.2 in2 = 0.023 m2 p = F/A =200/(2 x 36.2) = 2.8 psip = 891/(2 x 0.023) = 19 kPa Force = 4,000 lb = 17,800 N Foot Area = 43.5 in2 = 0.028 m2 p = F/A =4000/(4 x 43.5) = 23. psip = 17800/(4 x 0.028) = 159 kPa Force = 100 lb = 445 N Foot Area = 12.7 in2 = .0082 m2 p = F/A =100/(2 x 12.7) = 3.9 psip = 445/(2 x 0.0082) = 27 kPa

  10. Physics 1710—Chapter 14 Fluid Dynamics p = 19 kPa p = 159 kPa p = 27 kPa 0 Force = 100 lb = 445 N Heel Area = 0.16 in2 = .0001 m2 p = F/A =100/(2 x 0.16) = 313. psip = 445/(2 x 0.0001) = 2200. kPa

  11. Physics 1710—Chapter 14 Fluid Dynamics 0 The Mysterious Swami Seat

  12. Physics 1710—Chapter 14 Fluid Dynamics 0 80/20Pressure = Force per unit Area p = F /A Same Force Different Area ∴Different Pressure

  13. Physics 1710—Chapter 14 Fluid Dynamics 0 Pressure is the hydraulic stress: Hydraulic Stress: Bulk Modulus B Stress = modulus x strain σ = F/A = p = B ε = B ΔV/V ΔV P V

  14. Physics 1710—Chapter 14 Fluid Dynamics P 0 Pressure is isotropic: V

  15. Physics 1710—Chapter 14 Fluid Dynamics P P P P 0 F1= A1P; F2 = A2P Pressure is isotropic:

  16. Physics 1710—Chapter 14 Fluid Dynamics h F P 0 F = m g = (Ah)ρfluid g P = F/A = ρfluid g h A Hydrostatic Pressure is due to weight of fluid above:

  17. Physics 1710—Chapter 14 Fluid Dynamics P P 0 F = AΔP - mg= A ρfluid g Δh – mg F = Fbouyant - mg Fbouyant = ρfluid g V Archimedes Pressure A V - mg

  18. Physics 1710—Chapter 14 Fluid Dynamics P P 0 Fbouyant = ρfluid g V Archimedes Pressure V - ρfluid V g

  19. Physics 1710—Chapter 14 Fluid Dynamics 0 V constant if fluid is incompressible. A1v1 = A2v2 Continuity

  20. 0 Physics 1710—Chapter 14 Fluid Dynamics ΔW = ½ m v2 + mg y dW/dV = ½ ρ v2 +ρg y = d (Fy)/dV = dF/dA =ΔP ½ ρ v2 +ρg y =ΔP Work done on fluid

  21. Physics 1710—Chapter 14 Fluid Dynamics Summary: Pressure is the force per unit area. P =F/A Unit of pressue [Pacal] = [N]/[m2] The hydrostatic pressure is P = Po + gh Archimedes’ Principle: Fbouyant = ρfluid g V Equation of Continuity: A1v1 = A2v2 Bernoulli’s Equation:P + ½ ρv2 + ρgy = constant.

  22. Physics 1710—Chapter 11 App: E & E No Talking! Think! Confer! Why does the platform spin faster when he brings his arms in? Peer Instruction Time

  23. Physics 1710—Chapter 11 App: E & E 10 0% 0 of 1 Answer Now ! Why does the platform spin faster when he brings his arms in? • He increases his angular momentum. • He increase his moment of inertia. • He decrease his moment of inertia. • He pushes against the inertia of the weights. • None of the above

  24. Physics 1710—Chapter 14 Fluid Dynamics 10 0% 0 of 1 Answer Now ! Where should the fulcrum be place to balance the teeter-totter?

  25. Physics 1710—Chapter 14 Fluid Dynamics 10 0% 0 of 1 Answer Now ! Which way will the torque ladder move? • Clockwise • Counterclockwise • Will stay balanced

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