1. Motion, Forces, and Simple Machines

2. 1. Average speed is defined as the total distance traveled divided by the travel time. *The formula used to calculate average speed is: s=d/t *To find the distance (d), the formula changes to: d=s x t 2. instantaneous speed is the speed of an object at any instant of time. 3. Velocity is the speed of an object and its direction of motion 4. acceleration describes how velocity changes with time Formula: A = change in speed/time

3. 5. Force: a push or pull; is measured in newtons; causes an object to accelerate, and can change the direction of an objects motion. Example: Gravity is a pull that all objects exert on each other

4. A. Newton’s First Law States: An object at rest stays at rest unless an unbalanced force acts on it. *An object moving in a straight line at constant speed will continue doing that unless acted on by a force. This force is called friction. It is a force that resists motion between 2 surfaces that are in contact. It always acts opposite to the direction of motion. Sir Isaac Newton

5. * Inertia is the tendency to resist a change in motion. * The more mass (amount of matter in an object) an object has, the greater the inertia. ** Example: A toothpick has less inertia than a pencil because it has less mass.

6. B. Newton’s Second Law * States: A net force changes the velocity of the object and causes it to accelerate. *The more mass or inertia an object has, the harder it is to accelerate. More mass = less acceleration ** Example: pushing a refrigerator vs. pushing a grocery cart

7. C. Newton’s Third Law States: Forces always occur in equal but opposite pairs. In other words, for every action, there is an equal and opposite reaction. States: Forces always occur in equal but opposite pairs. In other words, for every action, there is an equal and opposite reaction. ** Example: A rocket blasting off Space Shuttle Columbia

9. 7. Work and Simple Machines * A. Work is defined as when a force causes an object to move in the same direction that the force is applied. It is measure in joules. * To calculate work, we use the following formula: W = f x d (f = force and d = distance) * Machines can change the size and direction of the force.

10. b. Simple machines: machines that use only one movement. **Examples: inclined plane, wedge, screw, lever, wheel and axle, pulley c. Compound machines: combination of simple machines **Example: can opener (wedge and inclined plane) d. Ideal machine: machine where there is no friction; the work done by the input force is equal to the work done by the output force.

11. Types of Simple Machines A. Pulley * object with a groove, like a wheel, with a rope or chain running through the groove. * Changes the direction of the input force. * Example: flagpole

12. B. Lever * First simple machine ever invented by humans * Rod or plank that pivots around a fixed point. The pivot point is called the fulcrum. *There are 3 types: first class (screwdriver) second class (wheelbarrow) and third class (hockey stick) * A lever can increase force or increase the distance or increase the distance over which a force is applied. over which a force is applied. * Example: pry bar

13. C. Wheel and axle * 2 round objects that are attached and rotate together about the same axis. The larger object is the wheel and the smaller object is the axle.Example: doorknob d. Inclined plane * Sloped surface, sometimes called a ramp * Allows you to lift a heavy load by using less force over a greater distance Example: ramp Wheel and axle Inclined plane

14. e. Wedge * Moving inclined plane with one or two sloping slides * Changes the direction of the force you apply * Example: front teeth, knives, axes f. Screw * An inclined plane wrapped around a post * Like a wedge, it also changes the direction of the force you apply. * Example: a screw screw Log-splitting wedge

16. ADD THE INFORMATION FROM THE NEXT TWO SLIDES TO BOTTOM OF THE NOTE TAKING SHEET

17. Energy *The ability to do work or cause change

18. Energy comes in many forms. There are 2 types of energy that relate to motion: 1. Potential energy - stored energy/energy of position example: roller coaster at the top of a hill or holding a ball in your hand 2. Kinetic energy - energy in motion example: roller coaster going down a hill or dropping a ball and it bouncing