Biomechanics Biomechanical Principles Newtons Laws Learning Objectives Learning
Biomechanics Biomechanical Principles – Newton’s Laws
Learning Objectives Learning Objective: Define and apply Newton’s Laws of motion 1 - Inertia 2 - Acceleration 3 - Reaction Learning Outcomes: All: Describe Newton’s 3 Laws of motion Most: Apply Newton’s Laws to a variety of sporting examples Some: Explain how athletes can apply Newton’s Laws to maximise performance
Key Terms • Inertia – resistance of a body to change • Acceleration - change in velocity over time • Force = any interaction that, when unopposed, will change the motion of an object force = mass x acceleration (N) • Velocity = displacement / time • Momentum = the amount of motion a body has (kgm/s) momentum (Kgm/s) = mass (Kg) x velocity (m/s) • Impulse = force applied for a period of time Impulse = force x time (N-s) (Newton seconds) or Kgm/s
Newton’s First Law - Inertia • An object will continue to remain at rest or uniform motion unless acted upon by an external unbalanced force • An object will only move or change movement if a force acts on it • https: //www. youtube. com/watch? v=LEHR 8 YQ Nm_Q&safe=active
Newton’s 2 nd Law- Acceleration • The rate of change of momentum of an object is directly proportional to the unbalanced force in the direction of force • The bigger the force, the faster an object will move. • A bigger object needs a larger force to move it • https: //www. youtube. com/watch? v=Zv. Prn 3 a. BQ G 8&safe=active
Newton’s 3 rd Law of Motion • For every action there is an equal and opposite reaction • https: //www. youtube. com/watch? v=Egqc. Gr. B 3 re 8&safe=active
Newton’s Laws in Sport Task: - create a video to demonstrate each of Newton’s Laws in action in sports - in your video you must explain how each of Newton’s laws is applied and show the performance can be maximised using the law
Example Newton’s First Law - Inertia • Football Free kick https: //www. youtube. com/watch? v=2 VRAT 4 wd. R MQ • The ball won’t move unless it’s kicked – force from the leg action upon it. • Pushing a car • https: //www. youtube. com/watch? v=fpn. G 3 p. RUgl o • You need more force to push a bigger object
Example Newton’s First Law - Acceleration • Shot put https: //www. youtube. com/watch? v=r. JOWTgr pfmc https: //www. youtube. com/watch? v=zs 97 EQNJT FA&safe=active • The bigger the force- the faster the object will go
Example • Newton’s 3 rd Law – Reaction • Trampolining • https: //www. youtube. com/watch? v=kdx 4 Ab. R 8_90&safe=active • When you push down on the trampoline, it pushes you back up • The more force pushed down, the more force pushes you up, the higher you go
Calculating Momentum • A rugby player mass 90 Kg is running at 10 m/s. What is the players momentum? • momentum = 90 Kg 10 m/s = 900 Kgm/s • A 4 man bobsleigh crew mass 630 Kg (the maximum allowable by the rules) is travelling at 42. 5 m/s (the current world record at 153 Km/hour). What is its momentum? • momentum = 630 Kg x 42. 5 m/s = 26 775 Kgm/s • How fast does the rugby player have to run to have the same speed as the bobsleigh travelling at 2 m/s? • bobsleigh momentum = 630 Kg x 2 m/s = 1260 Kgm/s • rugby player momentum (1260 Kgm/s) = 90 Kg x velocity therefore. . . velocity = 1260/90 = 14 m/s
Quick Quiz 1. 2. 3. 4. Describe Newton’s 1 st Law of Motion (1) Describe Newton’s 2 nd Law of Motion (1) Describe Newton’s 3 rd Law of Motion (1) Give an example of each of the Laws in action (3)
Exam Questions • June 2010 – 4 a (6)…. Using Newton’s Laws of Motion, explain the effect of the resultant force acting on the hockey ball. • Jan 2011 – 4 d (20) …. Use Newton’s Laws of Motion to explain the relationship between impulse and the motion of a high jumper during take off. • June 2012 – 4 b (5) Using Newton’s Laws of Motion, explain how, during take-off, a high jumper is able to maximise the height they can achieve
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