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Philosophiae Naturalis Principia Mathematica (1686)

Philosophiae Naturalis Principia Mathematica (1686). Law of Inertia A body at rest, or in constant motion will remain at rest, or in constant motion unless acted upon by a NET FORCE. Newton’s 1 st Law of Motion. Inertia is the resistance of an object to motion –

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Philosophiae Naturalis Principia Mathematica (1686)

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  1. Philosophiae Naturalis Principia Mathematica (1686)

  2. Law of Inertia A body at rest, or in constant motion will remain at rest, or in constant motion unless acted upon by a NET FORCE. Newton’s 1st Law of Motion Inertia is the resistance of an object to motion – The amount of resistance varies directly with the mass.

  3. Newton’s 1st Law of Motion

  4. The acceleration is in the direction of the net force. The acceleration is directly proportional to the net force, and inversely proportional to the mass. Newton’s 2nd Law of Motion

  5. Force causes acceleration M M M Newton’s 2nd Law of Motion F a F a F a • More force = more acceleration • Doubling the force doubles the acceleration

  6. Acceleration: Time Rate of change of velocity (Requires a Net Force) A NET FORCE always is needed to produce an acceleration

  7. Newton’s 2nd Law of Motion m - measured in kg a - measured in m/s2 Therefore: Force – measured in kg x m/s2 - Newton(N)

  8. Acceleration due to GravityForce (gravity) is same for all objects regardless of mass. Gravity acceleration force on earth is: g = 9.8 m/s2. 2. The ratio of the gravitational force to the mass is the same for all objects.

  9. Newton’s 2nd Law of Motion How much horizontal net force is required to accelerate a 1,000 kg car at 2 m/s2?                                                        

  10. What does the slope of a Force vs. Acceleration graph give? Slope = Mass Force (N) Acceleration (m/s2)

  11. “Law of Action and Reaction” When one body exerts a force on another body, the second exerts an equal but opposite force back on the 1st body “For every action (force) there is an equal and opposite reaction (force)” Newton’s 3rd Law of Motion Can you identify 6 pairs of action reaction forces?

  12. Newton’s 3rd Law of Motion

  13. Newton’s 3rd Law of Motion For every action (force) there is an equal and opposite reaction (force.)

  14. Demolition Derby Newton’s 3rd Law of Motion When two cars of different size collide, the forces on each is the SAME in magnitude (but in opposite direction). However, the same force on a smaller car means a bigger acceleration!

  15. Newton’s 3rd Law of Motion

  16. A mass of 20 kg is pulled horizontally by a force of 25N at an angle • of 300 to the horizontal, if the frictional force is 3 Newtons: • Draw a free body diagram showing all the forces on the block. • Find the normal force • Calculate the acceleration of the block

  17. Find the tension in each cord for the systems shown in Figure. (Neglect the mass of the cords!).

  18. A 25-kg block is initially at rest on a horizontal surface. A horizontal force of 75 N is required to set the block in motion. After it is in motion, a horizontal force of 60 N is required to keep the block moving with constant speed. Find the coefficients of static and kinetic friction from this information

  19. 10 Newtons • What is the magnitude of the acceleration of a 2 kg object • when the net force on the object is 10 N? • 10 m/s2 • 20 m/s2 • 5 m/s2

  20. A 0.5 kg model airplane is initially at rest. If a 10N force is applied to it for 2 s, its final velocity would be 5 m/s 20 m/s 40 m/s 10 m/s 30 m/s 10 N

  21. A 15 N force is applied to a mass M that is adjacent to the wall, as shown below. If the mass is 2 kg, the force that the wall exerts on the mass is equal to: • 0 N • 2 N • 15 N • 19.6 N • 30 N

  22. In the diagram below, a force F is applied to a mass M at an angle  with the horizontal. What is the magnitude of the normal force? • Mg – F sin  • Mg + F sin  • Mg / F sin  • F sin  / Mg • Mg

  23. In the figure, the coefficient of sliding friction between the small block and the table top is 0.2. If the pulley is frictionless and massless what will be the acceleration of the blocks once they are released from rest? • 0.5g • 0.6g • 0.7g • 0.8g • 0.9g

  24. A mass M rests on top of a frictionless inclined plane. Which of the following statements is correct about the normal force acting on the mass as the angle of Elevation increases? • The normal force increases • The normal force decreases • The normal force increases, then decreases • The normal force decreases, then increases • The normal force remains constant

  25. The coefficient of static friction between a box and a ramp is 0.5. The ramp’s incline angle is 30 degrees. If the box Is placed at rest on the ramp, the box will: • Accelerate down the ramp • Accelerate briefly down the ramp then slow down and stop • Move with constant velocity down the ramp • Remain at rest • None of the above

  26. When bottom (Smoothest) block is struck with hammer, it slides quickly from under the top blocks, which drop very nearly straight down.

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