2.  Isaac Newton  Smart Guy  Liked Apples  Invented Calculus  Came up with 3 laws of motion  Named stuff after himself

3.  Inertia is how much an object resists a change in its velocity.  Measured by mass

4.  An object at rest stays at rest unless acted on by an external force. An object in motion continues to travel with constant velocity unless acted on by an external force.  Law of Inertia

5.  The acceleration of an object is in the direction of the net external force acting on it. It is proportional to the net external force, and is inversely proportional to the mass of the object. -- or --

6.  When two objects interact they each exert a force on the other. These forces are equal in magnitude and opposite in direction.  Forces always occur in pairs

7. “Action-Reaction” forces never cancel out because they act on different objects.

10.  F = ma  m is measured in kg  a is measured in m/s 2  F is measured in kg m/s 2, called a Newton (N)

11.  Acts at a distance (gravitational field)  Force due to Gravity = Weight  Acceleration due to Gravity = Constant  g = 9.8 m/s 2

12.  Contact Force  Acts perpendicular to the surface

13.  Contact force  Acts parallel to the surface  Acts opposite the direction of motion

14.  Contact force  Acts opposite the direction the spring is stretched or compressed  Proportional to stiffness of spring and how much it is stretched or compressed

15.  k = spring constant (N/m)  x = displacement from equilibrium (m)  negative shows direction

16.  Contact force  Force exerted by a string or rope  Always acts along the string or rope  Equal on both ends of the string or rope* * Unless you have a pulley with mass, like in AP Physics

19.  Friction is a resistive force caused by two surfaces sliding across each other.  Always acts opposite the direction of motion

20.  Static Friction - F s  Friction force between two stationary surfaces.  Kinetic Friction – F k  Friction force between two sliding surfaces.  F s is always greater than F k  Harder to start moving than to keep moving

21.  Coefficient of friction describes how rough the surface is. Higher is rougher.  Denoted by the Greek letter mu (μ)  pronounced “mew”  μ s = coefficient of static friction  μ k = coefficient of kinetic friction  μ is always positive, usually between 0 and 1.

22.  Regardless of type (static or kinetic)  To find static friction, use μ s  To find kinetic friction, use μ k

25. 1. Draw the object and ALL forces acting ON the object 2. Draw and label all forces as vectors starting on the object and pointing the direction the force is acting 3. Draw and label the direction of acceleration as a vector that doesn’t touch the object

26.  Draw the FBD for a box sitting at rest on a table. FNFN FgFg

27.  Draw the FBD for a box being pushed across a rough table at a constant speed. FNFN FgFg F push FfFf v

28.  Draw the FBD for a box being accelerated to the right across a rough table. FNFN FgFg F push FfFf a

29.  Draw the FBD for a box sliding down a rough hill. FNFN FgFg FfFf a

30.  Draw the FBD for a box hanging from a rope. T FgFg

31.  FBDs are used to set up net force equations  Net force equations will be used to solve all Newton’s Laws problems.

33.  For any individual force F = ma  For all forces on an object F net = ma  F net = vector sum of all forces acting on an object  Separate F net equations for x and y directions

34.  For each object: 1. Draw a Free Body Diagram 2. Resolve forces at angles into x & y components using sine and cosine 3. Direction of acceleration is the positive direction 4. Write F net equations in x & y directions 5. Solve

35.  x-direction  y-direction FNFN FgFg F push FfFf a

36.  x-direction  y-direction T FgFg a