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Newton’s 2nd law of motion 2014

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Laura Smith
Laura Smith

* Audrey moved a 12kg box at an acceleration of 5m/s^2 * Using the formula Force = Mass x Acceleration * Mass of the box is 12kg * Acceleration is 5m/s^2 * Therefore, Force = Mass x Acceleration = 12kg x 5m/s^2 = 60N The amount of force required to move the 12kg box at a rate of 5m/s^2 is 60N.

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Newton’s Second Law of Motion 8th Science
Force = Mass x Acceleration (F=ma) • AKA: the “Law of Force and Acceleration” • Newton’s second law states that the amount of force is equal to an objects mass times its acceleration. • The acceleration of an object is directly proportional to the net force & indirectly proportional to its’ mass.
Getting Started • First, you need to know the units of Force, Mass & Acceleration. – The units used for force are Newtons (N) – The units used for mass are kilograms (kg) – The acceleration units are meters per second squared (m/sec2).
Acceleration • Is a change in velocity – Speeding up • Positive acceleration – Slowing down • Negative acceleration • Deceleration – Changing direction • unbalanced forces cause objects to accelerate.
Acceleration • Acceleration is directly related to the size of the force and the direction of the force. • It accelerates in the direction you push or pull it.
In other words…. Large Force = Large Acceleration F a
In other words…. Small Force = Small Acceleration F a So….if you push twice as hard, it accelerates twice as much.
But there is a twist…. • Acceleration is INVERSELY related to the mass of the object.
In other words…..using the same amount of force…. F Small acceleration Large Mass a F Small Mass Large acceleration a
Calculating Acceleration • Acceleration Equation Acceleration = (final speed (in m/s) – initial speed (in m/s)) Time (in seconds) A= (sf-si) t
Calculating Speed • Comparison of time and distance – Distance traveled per unit time – Speed = distance ÷ time
Calculating Speed Given Distance & Time D S T Speed = Distance Time Speed = Distance ÷ Time
Let’s Practice • Riley chucks a water balloon at a big, mean looking guy at the park. Running for his life, he travels 100m in 9.83s. What was his average speed? S= Distance/time S= d/t S= 100m/9.83s S=10.17 mps (meters per second)
Calculating Distance Given Speed & Time D S T Distance = Speed • Time Multiply Speed and Time Distance = Speed X Time Speed X Time = Distance
Let’s Practice 1. If you ran 15 km/h for 20 min, how much distance would you cover? Distance = Speed x time D=ST D=15 km/h x (20 min/60) D =
Calculating Time Given Distance and Speed D S T Time = Distance Speed Divide Distance by Time Distance ÷ Speed = Time Time = Distance ÷ Speed
Let’s Practice • Marcy doesn't want to be late for class so she rushes to McDonald’s at lunch. How much time would it take Marcy to walk 2 km to McDonalds for a Big Mac if she walked at a rate of 4.5 km/h? Time = distance/speed T=DS T = 2km / 4.5 km/h T= .44 hours or 26.4 minutes
Calculating Acceleration • Acceleration Equation Acceleration = (final speed (in m/s) – initial speed (in m/s)) Time (in seconds) A= (sf-si) t Oh… I get it now!
Let’s practice… • Rob is really bored one Saturday night and goes outside to study the nocturnal habits of mice in the hayfield. He sees a mouse sniffing along at 0.1 m/s. but it hears and starts to scurry for safety. In just 3.7 s it accelerates to 0.9 m/s. Find its acceleration.
Let’s Practice Acceleration = (final speed (in m/s) – initial speed (in m/s)) Time (in seconds) A= (sf-si) t A= 0.9m/s – 0.1 m/s 3.7s A= 0.8m/s 3.7s A= 0.22 m/s2
Let’s Practice • A roach moves down the hall at 1.2 m/s. When he sees the janitor coming down the hall, he begins to run. After 3.2 s, he is moving at 3.6 m/s. What is his acceleration?
Calculating Force Given Mass and Acceleration F M A Force = Mass x Acceleration Multiply Mass and Acceleration Force = Mass x Acceleration Mass x Acceleration = Force
Let’s Practice • While showing off for some girls at the skate park, Josh D crashes. Josh has a mass of 68 kilograms and an acceleration of 2m/s2 what is Force of Joshes fall? • F=ma • F= 68Kg x 2m/s2 • F= 136N
Calculating Mass Given Force and Acceleration F M A Mass = Force ÷ Acceleration Divide Force by Acceleration Mass = Force ÷ Acceleration Force ÷ Acceleration = Mass
Let’s Practice • Colin skateboards down the sidewalk in front of the school, he pushes of with a force of 16N and accelerates at a rate of 4m/s2. What is Colin’s mass? • M = F ÷ A • M = 16N ÷ 4m/s2 • M = 4Kg
Calculating Acceleration Given Force and Mass F M A Acceleration = Force ÷ Mass Divide Force and Mass Acceleration = Force ÷ Mass Force ÷ Mass = Acceleration
Let’s Practice • Jenna dove off the diving board at camp with a force of 36N. Jenna’s mass is 6Kg. What is her rate of acceleration? • A = F ÷ M • A = 36N ÷ 6Kg • A = 6m/s2
Product: • Audrey moved into a new home on Friday. While moving boxes, she attempted to calculate the amount of force required. The final 12Kg box was moved at a rate of 5m/s2. What amount of force was required to move the box?

More Related Content

Newton’s 2nd law of motion 2014

  • 1. Newton’s Second Law of Motion 8th Science
  • 2. Force = Mass x Acceleration (F=ma) • AKA: the “Law of Force and Acceleration” • Newton’s second law states that the amount of force is equal to an objects mass times its acceleration. • The acceleration of an object is directly proportional to the net force & indirectly proportional to its’ mass.
  • 3. Getting Started • First, you need to know the units of Force, Mass & Acceleration. – The units used for force are Newtons (N) – The units used for mass are kilograms (kg) – The acceleration units are meters per second squared (m/sec2).
  • 4. Acceleration • Is a change in velocity – Speeding up • Positive acceleration – Slowing down • Negative acceleration • Deceleration – Changing direction • unbalanced forces cause objects to accelerate.
  • 5. Acceleration • Acceleration is directly related to the size of the force and the direction of the force. • It accelerates in the direction you push or pull it.
  • 6. In other words…. Large Force = Large Acceleration F a
  • 7. In other words…. Small Force = Small Acceleration F a So….if you push twice as hard, it accelerates twice as much.
  • 8. But there is a twist…. • Acceleration is INVERSELY related to the mass of the object.
  • 9. In other words…..using the same amount of force…. F Small acceleration Large Mass a F Small Mass Large acceleration a
  • 10. Calculating Acceleration • Acceleration Equation Acceleration = (final speed (in m/s) – initial speed (in m/s)) Time (in seconds) A= (sf-si) t
  • 11. Calculating Speed • Comparison of time and distance – Distance traveled per unit time – Speed = distance ÷ time
  • 12. Calculating Speed Given Distance & Time D S T Speed = Distance Time Speed = Distance ÷ Time
  • 13. Let’s Practice • Riley chucks a water balloon at a big, mean looking guy at the park. Running for his life, he travels 100m in 9.83s. What was his average speed? S= Distance/time S= d/t S= 100m/9.83s S=10.17 mps (meters per second)
  • 14. Calculating Distance Given Speed & Time D S T Distance = Speed • Time Multiply Speed and Time Distance = Speed X Time Speed X Time = Distance
  • 15. Let’s Practice 1. If you ran 15 km/h for 20 min, how much distance would you cover? Distance = Speed x time D=ST D=15 km/h x (20 min/60) D =
  • 16. Calculating Time Given Distance and Speed D S T Time = Distance Speed Divide Distance by Time Distance ÷ Speed = Time Time = Distance ÷ Speed
  • 17. Let’s Practice • Marcy doesn't want to be late for class so she rushes to McDonald’s at lunch. How much time would it take Marcy to walk 2 km to McDonalds for a Big Mac if she walked at a rate of 4.5 km/h? Time = distance/speed T=DS T = 2km / 4.5 km/h T= .44 hours or 26.4 minutes
  • 18. Calculating Acceleration • Acceleration Equation Acceleration = (final speed (in m/s) – initial speed (in m/s)) Time (in seconds) A= (sf-si) t Oh… I get it now!
  • 19. Let’s practice… • Rob is really bored one Saturday night and goes outside to study the nocturnal habits of mice in the hayfield. He sees a mouse sniffing along at 0.1 m/s. but it hears and starts to scurry for safety. In just 3.7 s it accelerates to 0.9 m/s. Find its acceleration.
  • 20. Let’s Practice Acceleration = (final speed (in m/s) – initial speed (in m/s)) Time (in seconds) A= (sf-si) t A= 0.9m/s – 0.1 m/s 3.7s A= 0.8m/s 3.7s A= 0.22 m/s2
  • 21. Let’s Practice • A roach moves down the hall at 1.2 m/s. When he sees the janitor coming down the hall, he begins to run. After 3.2 s, he is moving at 3.6 m/s. What is his acceleration?
  • 22. Calculating Force Given Mass and Acceleration F M A Force = Mass x Acceleration Multiply Mass and Acceleration Force = Mass x Acceleration Mass x Acceleration = Force
  • 23. Let’s Practice • While showing off for some girls at the skate park, Josh D crashes. Josh has a mass of 68 kilograms and an acceleration of 2m/s2 what is Force of Joshes fall? • F=ma • F= 68Kg x 2m/s2 • F= 136N
  • 24. Calculating Mass Given Force and Acceleration F M A Mass = Force ÷ Acceleration Divide Force by Acceleration Mass = Force ÷ Acceleration Force ÷ Acceleration = Mass
  • 25. Let’s Practice • Colin skateboards down the sidewalk in front of the school, he pushes of with a force of 16N and accelerates at a rate of 4m/s2. What is Colin’s mass? • M = F ÷ A • M = 16N ÷ 4m/s2 • M = 4Kg
  • 26. Calculating Acceleration Given Force and Mass F M A Acceleration = Force ÷ Mass Divide Force and Mass Acceleration = Force ÷ Mass Force ÷ Mass = Acceleration
  • 27. Let’s Practice • Jenna dove off the diving board at camp with a force of 36N. Jenna’s mass is 6Kg. What is her rate of acceleration? • A = F ÷ M • A = 36N ÷ 6Kg • A = 6m/s2
  • 28. Product: • Audrey moved into a new home on Friday. While moving boxes, she attempted to calculate the amount of force required. The final 12Kg box was moved at a rate of 5m/s2. What amount of force was required to move the box?