1. Newton’s Laws of Motion

3.  A force is a push or a pull  A force is a vector  Force has both magnitude and direction  Unit for force is Newtons (N)

4.  When a more than one force acts on a body at the same time, each individual force is called a component force  The total sum of all the component forces acting on an object is the resultant force  For any one object, there can be several component forces, but only be one resultant force.  Sometimes, resultant force is also called “net force”

5.  When there is no resultant force (or resultant force = 0), the object is said to be balanced  When there is a resultant force, the object is said to be unbalanced.  We will discuss more about balanced and unbalanced forces in this chapter, and later in chapter 5.

6.  Textbook on Penny Board (stationary)  Learning Point: An object at rest will want to remain at rest – this effect is sometimes referred to as “inertia”  Another illustration: when you are standing still in a stationary bus, and the bus suddenly accelerates forward

7.  Textbook on Penny Board (moving)  Learning Point: an moving in a straight line will want to continue moving in a straight line.  Another illustration: when a vehicle suddenly brakes  Application: Safety features of a Car (seatbelt and headrest)

8.  When there is no resultant force (i.e. balanced forces)  An object at rest remains at rest  An object in uniform motion remains in uniform motion  uniform motion = travelling in a straight line AND constant speed

9.  BMW Motorbike Table Cloth Trick http://www.youtube.com/watch?v=vfnt8Sdj7cs http://www.youtube.com/watch?v=vfnt8Sdj7cs  Mythbusters Attempt (Part 1) http://www.youtube.com/watch?v=_faLNmcAR eA http://www.youtube.com/watch?v=_faLNmcAR eA  Mythbusters Attempt (Part 2) http://www.youtube.com/watch?v=cuSAQX5Ze Yg http://www.youtube.com/watch?v=cuSAQX5Ze Yg  How it’s really done? http://www.youtube.com/watch?v=j4cbYkm2N Uk http://www.youtube.com/watch?v=j4cbYkm2N Uk

10.  Pull a light person sitting on a pennyboard (constant force)  What do you observe while the person is being pushed? Is the speed constant?  Push a heavier person with the same force.  Push the same person, but with a larger force.  What do you observe?

11.  When there is a resultant force F resultant,  The object experiences an acceleration in the same direction of F resultant  This acceleration is the ratio of F resultant to the mass of the object  Equation form: F resultant = ma

12.  Textbook Pg 54, Work Example 3.2  A boy pushes a stationary box of mass 20 kg with a force of 50 N. Calculate the acceleration of the box (assume no friction)  F= ma  a = F/m  = (50)/(20)  = 2.50 ms -2 in the direction of the applied force

13.  Newton’s First Law:  Object at rest remains at rest  Object in uniform motion remains in uniform motion  Newton’s Second Law:  F = ma