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Warm-Up, Tuesday December 13

If you are not wearing a seat belt and the car you are in suddenly stops, how will your body move? Is this a type of acceleration?. Warm-Up, Tuesday December 13. Yes, you are accelerating because you have a change of direction. You will be thrown forward. What moves you?. Human Ingenuity.

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Warm-Up, Tuesday December 13

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  1. If you are not wearing a seat belt and the car you are in suddenly stops, how will your body move? Is this a type of acceleration? Warm-Up, Tuesday December 13 Yes, you are accelerating because you have a change of direction. You will be thrown forward.

  2. What moves you? Human Ingenuity Knowledgeable, Inquirer • MYP Question: • AoI: • IB Learner: • EQ: • What is the relationship between velocity and acceleration? S8P3. Students will investigate relationship between force, mass, and the motion of objects. Determine the relationship between velocity and acceleration. b. Demonstrate the effect of balanced and unbalanced forces on an object in terms of gravity, inertia, and friction.

  3. Work Session Check Directed Reading 6 Notes: Newton’s 2nd Law of Motion

  4. Opening: Tug of War Part I: Two students each hook a spring scale onto a string. Both students pull on the string with 2 Newtons of force. - Describe the force acting on the string (balanced or unbalanced). - Is the force a push or pull motion? - What is the motion of the string?

  5. Tug of War (Part II) One student exerts 5 Newtons of force on the string. One student exerts 3 Newtons of force on the string. - Describe the force acting on the string (balanced or unbalanced). - What is the motion of the string? Part I: Balanced Force – string isn’t moving; pull motion Part II: Unbalanced force – string moves toward the student with 5 Newtons

  6. Yes, write this down. Units of Measurement: • Mass – kilograms • Force - Newtons One Newton (N) is force required to accelerate 1 kg mass 1 meter per second per second. • Acceleration - meter per second per second (1 m/s2) Think miles per hour – if your speed increases one mph every hour your acceleration would be one mile per hour per hour.

  7. Newton’s 2nd Law of Motion The acceleration of an object depends on the mass ofthe object and the amount of force applied. Confusing! I know, I’ll CHUNK it. • The acceleration of an object (horizontally) • * depends on the mass ofthe object. • * depends on the amount of force • applied.

  8. Newton also stated, “The acceleration of an object is directly proportional to the net force & inversely proportional to it’s mass.” What does that mean?? • Simply: • As force increases, acceleration increases • As mass increases, acceleration decreases.

  9. Expressing Newton’s 2nd Law mathematically A = F or F = m x a m Newton’s second law explains why objects fall to Earth with the same acceleration. Force = mass x acceleration

  10. A B C You have to exert only a small force on the cart to accelerate it. B. The same amount of force will not accelerate the full cart as much as the empty cart. A greater force is needed to accelerate the full cart.

  11. Look at the figure below. Determine the rate of acceleration. Use the formula F= M x A Multiply both sides by M F = M x A F = M x A M M A = Force/Mass = 100N/50 kg = 50 m/s2

  12. Sample Problem (IAN – with notes)62) What is the net force on a 52kg water skier being accelerated at 2 m/s2 Force = mass x acceleration F = 52 Kg x 2 m/s2 = 104 Kg x m/s2 kg F = 104 m/s2 Convert Units

  13. Suppose that an elephant and a feather are dropped off a very tall building from the same height at the same time. • Suppose also that air resistance could somehow be eliminated such that neither the elephant nor the feather would experience any air drag during the course of their fall. • Which object - the elephant or the feather - will hit the ground first? In the absence of air resistance, they fall at the same rate of acceleration.Free Fall = 9.8 m/s2.

  14. Since we DO have to account for air resistance while on Earth, the _________ will fall to earth faster. elephant • The elephant has more mass than the feather. • Greater mass equals, a greater force of gravity. • The elephant continues to accelerate . . . The feather reached terminal velocity.

  15. Closing Physics of Sky Diving

  16. Closing • Using Newton’s 2nd Law of Motion, explain what is happening in the image below. (The elephant is on roller skates.) Will the elephant move? Explain your answer. Use terms such as mass, force, and Newtons.

  17. Warm-Up Here's a block which is not moving and has two forces on it. One force points to the left and the other to the right. The forces are equal. What will the block’s subsequent motion be? Stationary(no movement) the forces are balanced.

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