After you have picked up the paper up front, look over it to see if you know any of the quesions already.

Chapter 3.1 Notes

Isaac Newton ”Discovered” gravity Invented calculus Devised 3 laws of motion

Newton’s 1 st Law An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted on by an unbalanced force. –Law of Inertia

Force If I asked you to move a cart containing a large, heavy box, what would you do?: (a) push it (b) pull it (c) yell at it till it moved A force is simply a push or a pull (or any action that can cause a change in motion). –But doesn’t have to cause a change in motion

How to Measure Force Newtons – The SI unit for force Pounds – The English unit for force (such as in weight)‏ –There are 4.48 Newtons in 1 pound N = kg*m/s 2 –1N can move 1 kg at an acceleration of 1 m/s 2

Combining Forces All forces acting on an object combine to form the net force. If the forces are balanced (net force = 0), the object is in equilibrium – thus no change in motion Force is a vector like velocity

Friction Always resists motion Static Friction – resistance to starting to move a resting object Air Friction - Stick your hand out a car/bus window and feel the air push against it Sliding/Rolling Friction – When two surfaces rub against each other, such as sliding a wooden block across a table or when a wheel turns on pavement. –Traction utilizes friction

Inertia The property of an object to resist changing its state of motion Amount of inertia depends on objects mass –A semi is harder to move than a bicycle

Reminder about Mass Remember: –Mass is how much “stuff” is in an object –Weight is not the same as mass Mass is a property of an object and doesn’t change; weight does.

Video Introduction