Newton's laws of motion
- 1. Prepared by: Kayraine Mae E. Caballero, LPT
- 2. This pit crew member is pushing a race car forward. Is the race car pushing back on him? If so, does it push back with the same magnitude of force or a different amount?
- 3. Is a push or pull exerted by an object on another or by the body on the environment. Vector quantity that has magnitude and direction. FORCE
- 4. 2 TYPES OF FORCES CONTACT FORCES - Force between bodies that are in direct contact with each other. 1. Normal Force 2. Friction Force 3. Tension Force
- 5. Normal Force Exerted on an object by any surface that it is contacted with. Perpendicular always to the surface of contact even t any angle.
- 6. Friction Force Exerted on an object by a surface, directed parallel to the surface.
- 7. Tension Force Pulling force exerted by a stretched rope on an object which it is attached.
- 8. 2 TYPES OF FORCES NON-CONTACT FORCES - Force that acts even if interacting bodies are separated by distance. 1. Gravitational Force 2. Electrostatic force
- 9. 4 Fundamental Forces Gravitational Force Electromagnetic Force Strong nuclear Force Weak Nuclear Force
- 11. LAW OF INERTIA What is Inertia? -The tendency of a body to resist in the change of state of motion whether in motion or motionless. Newton’s First law of Motion!
- 12. - “An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by a net force.” Fnet=0 Law of Inertia Newton’s First Law of Motion
- 13. Two Clauses and a Condition
- 14. •Once airborne, unless acted on by an unbalanced force (gravity and air – fluid friction), it would never stop! •Unless acted upon by an unbalanced force, this golf ball would sit on the tee forever.
- 15. Application of Newton’s First Law Because of inertia, objects (including you) resist changes in their motion. When the car going 80 km/hour is stopped by the brick wall, your body keeps moving at 80 m/hour.
- 16. Newton’s Second Law Newton's second law of motion can be formally stated as: “The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.”
- 17. Newton’s Second Law THE BIG EQUATION a = Fnet / m Fnet = m • a 1 Newton = 1 kg • m/s2
- 18. Your Turn to Practice Net Force(N) Mass(kg) Acceleration(m/ s/s) 1. 10 2 2. 20 2 3. 20 4 4. 2 5 5. 10 1 10 The Fnet = m • a equation is often used in algebraic problem solving. The table below can be filled by substituting into the equation and solving for the unknown quantity. Try it yourself to solve. If mass remains constant, doubling the acceleration, doubles the force. If force remains constant, doubling the mass, halves the acceleration.
- 19. Application of Newton’s Second Law Think about the situation when you are pushing your bicycle versus when you are pushing your car. You require more force to be given to the car in order to move it at an equal acceleration as compared to force required to move your bicycle. Bicycle having less mass than a motor cycle accelerates at a lesser force applied on it. Alternatively, if three of your friends help you push the car, you can push the car easily as compared to you doing it alone. Hence, the mass remained the same but the increased force provided more acceleration!
- 20. CHECK YOUR UNDERSTANDING • 1. What acceleration will result when a 12 N net force applied to a 3 kg object? A 6 kg object? • 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2. Determine the mass. • 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? • 4. What is the force on a 1000 kg elevator that is freely at 9.8 m/sec/sec?
- 21. Newton’s Third Law of Motion “For every action, there is an equal and opposite reaction.”
- 22. Newton’s Third Law of Motion The statement means: • in every interaction, there is a pair of forces acting on the two interacting objects. • the size of the forces on the first object equals the size of the force on the second object. • the direction of the force on the first object is opposite to the direction of the force on the second object.
- 23. Newton’s Third Law of Motion According to Newton, whenever objects A and B interact with each other, they exert forces upon each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body.
- 24. Newton’s Third Law of Motion -a force on the chair -and a force on your body. These two forces are called action and reaction forces.
- 25. Application of Newton’s Third Law • Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. In turn, the water reacts by pushing the fish forwards, propelling the fish through the water.
- 26. Application of Newton’s Third Law • Flying gracefully through the air, birds depend on Newton’s third law of motion. As the birds push down on the air with their wings, the air pushes their wings up and gives them lift.
- 27. Other examples of Newton’s Third Law •The baseball forces the bat to the left (an action); the bat forces the ball to the right (the reaction).
- 28. Other examples of Newton’s Third Law •A car is equipped with wheels which spin backwards. As the wheels spin backwards, they grip the road and push the road backwards.
- 29. Newton’s Laws of Motion 1st Law - “An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by a net force.” 2nd Law - “The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.” 3rd Law “For every action, there is an equal and opposite reaction.”
Editor's Notes
- #3: But what causes bodies to move the way that they do?
- #5: Force exerted by the muscle to lift an object
- #10: Gravitational Force – attractive force exerted by objects with mass Electromagnetic Force – force that holds atoms and molecules together Strong Nucelar Force – force between protons and neutrons in a nucleus Weak Nuclear Force – plays a role in a radioactive decay
- #11: ISAAC NEWTON – founder of the science of Mechanics - first to describe the motion of a massive objects - Mathematical Principles of Natural Philosophy – where the 3 laws is contained
- #12: The greater the mass the greater the inertia, the greater the inertia the harder for the motion of the object to be change.
- #16: REPUBLIC ACT 8750 (SEAT BELT USE ACT OF 1999)
- #27: Action-reaction force pairs make it possible for birds to fly.