1. PS-5.7: Explain the motion of objects on the basis of Newton’s three laws of motion: inertia, the relationship among force, mass, and acceleration; and action and reaction forces PS-5.8: use the formula F = ma to solve problems related to force

2.  Newton’s Second law  When a net force acts on an object the object will accelerate in the direction of the net force The larger the net force, the greater the rate of acceleration The larger the mass of an object, the smaller the rate of acceleration  Acceleration can mean speeding up, slowing down, or changing direction

3.  Newton’s 2 nd Law can be described with a formula  Acceleration (m/s 2 ) = net force(N) / mass(kg)  a = F net / m  Pg. 69  Problem: you push a wagon that has a mass of 8kg. If the net force on the wagon is 4N, what is the wagon’s acceleration? What are the steps we should follow?  Do the practice problems on your own

4.  How can net force be found using the 2 nd law?  Rearrange the formula Force = mass * acceleration F = ma Unit of force is Newton

5.  Friction is the force that opposes the sliding motion of two surfaces that are touching each other  Amount of friction will depend on the kinds of surfaces and the force pressing the surfaces together

6.  Four types of friction  Sticking together A strong force pushes more of the surfaces together so a larger force is needed to the microwelds apart  Static Friction The frictional force that prevents two surfaces from sliding past each other  Sliding Friction Force that opposes the motion of two surfaces sliding past each other  Rolling Friction What happens when your car gets stuck in mud or on ice

7.  Air Resistance  Opposes the motion of objects that move through the air  Without air resistance all objects would fall with the same acceleration  Depends on the size and shape of the object Ex: penny and feather

8.  To every action force there is an equal and opposite reaction force  a.k.a. Law of Action and Reaction  The forces are equal and opposite but do not cancel each other out  Two objects, each with only one force acting on it