Newton’s Laws of Motion

1. Newton’s Laws of Motion

2. Newton’s First Law of Motion • An object at rest remains at rest, and an object in motion remains in motion, unless acted on by an unbalanced force • also called the “Law of Inertia” – the greater an object’s mass, the greater its inertia

3. Newton’s Second Law OF Motion • The acceleration of an object depends on the mass of the object and the amount of force applied to the object • Also called the “Law of Acceleration” – acceleration of an object increases as its mass decreases, and as the force applied increases

4. Acceleration, Force, and Mass • Explains why objects fall to Earth at the same rate a = F/m orF = m × a a = acceleration F = force m = mass A 50 kg skater pushes off from a wall with a force of 200 N. What is the skater’s acceleration? a = F/m = 200 N/50 kg = 4 m/s²

5. Newton’s Third Law of Motion • Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first • Also called the “Law of Action-Reaction” – all forces act in pairs, but never on the same object

6. Momentum • An object’s mass multiplied by its velocity • the more momentum an object has, the harder it is to stop or change direction • as mass and/or velocity of an object increases, the momentum of the object increases

7. Calculating Momentum p = m × v p = momentum m = mass v = velocity What is the momentum of an ostrich with a mass of 120 kg that runs with a velocity of 16 m/s north? p = m × v = 120 kg × 16 m/s north = 19,200 kg · m/s north

8. The Law of Conservation of Momentum • Any time objects collide, the total amount of momentum stays the same

9. Collisions • Move as one object with a mass equal to the combined masses of the objects • Move in the direction of the object with greater momentum • Momentum gets transferred to other objects causing them to move in different directions • Total momentum of all the objects remains the same Sticking Together Bouncing Off Each Other