 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

 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

 Explains why objects fall to Earth at the same rate a = F/m or F = 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

 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

 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

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

 Any time objects collide, the total amount of momentum stays the same

Sticking TogetherBouncing Off Each Other  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