2.3 newton´s first and second lawsPresentation Transcript
Chapter 2: Forces Miss Luzma Fabre
Section 3: Newton´s First and Second Laws If an object is not moving, it will not move unless a force acts on it
If an object is already moving, it will continue to move at a constant velocity until a force acts to change either its speed or direction
The First Law of Motion (or law of inertia) Newton´s first law of motion states that an object at rest will remain at rest, and an object moving at a constant velocity will continue moving at a constant velocity, unless it is acted upon by an unbalanced force
Inertia Is the tendency of an object to resist a change in motion Ex: moving forward in your seat when the car stops
Inertia depends on mass The greater the mass of an object is, the greater its inertia, and the greater the force required to change its motion Ex: full grocery cart vs empty grocery cart
How does Newton´s first law explain what happens to passengers when a car stops quickly?
The Second Law of Motion
Mass= 55 kg Acceleration= 2 Net force (F m/s2 net)= ?
Changes in force and mass Ways to increase acceleration: Mass or Force
Practice problems1. What is the net force on a 1000 kg object accelerating at 3 m/s2?2. What net force is needed to accelerate a 25 kg cart at 14 m/s2?3. What is the mass of a car that accelerates at a rate of 5 m/s2 due to a force of 4000 N?4. What is the acceleration of a 0.15 kg hockey puck that receives a net force of 1.8 N?