Chapter 13 – Forces in Motion

1. Chapter 13 – Forces in Motion

2. Types of Motion • Constant Motion – motion that is constant and steady

3. Types of Motion • Variable Motion – motion that moves in many directions and at many speeds

4. Types of Motion • Periodic Motion – back and forth steady movement

5. Types of Motion • Circular Motion – movement in circles

6. Types of Motion • Vibrational Motion – movement that is quick, back and forth vibrations

7. Speed • The distance an object travels in a certain amount of time. • To find the speed divide the distance and the time it took to go that distance • S = D/T • Sammy the Snail

8. Velocity Describes the speed and direction of an object’s motion. Example: The plane is moving west at 300mph. Speed and Velocity

9. Point of Reference Motion measured as a relationship between two objects. Reference point

10. Force • A push or a pull that acts on an object. • Forces can make a moving object speed up, slow down, or change directions.

11. Gravity • The force of attraction between two objects causing them to have weight. • Examples • Apple falling out of a tree. • Skydiver landing on the ground.

12. Magnetism • A force that pushes and pulls on other objects • Push – two north poles will push away from each other • Pull – a north pole and a south pole will pull toward each other

13. Electricity • All objects that are electrically charged will exert forces on each other. • Oppositely charged objects are attracted to each other. • Objects with the same chare are repelled, and move away from each other

14. Friction • The force between moving parts that tends to slow them down. Magic School Bus – Plays Ball

15. Work • Work is done when a force moves an object. • If the force does not make the object move, then no work has been done • Work is done only when the object moves

16. Power • The rate at which work is done. • Walking up a hill and running up the same hill take the same amount of work. Since running up the hill is faster than walking, the amount of power needed to run is greater.

17. Newton’s Laws of Motion The Science of Sports

18. Newton’s 1st Law of Motion • An object at rest stays at rest until a force acts on it. An object moving at a constant speed will continue to move in a straight line and at a constant speed until a force acts on it.

19. Inertia • The tendency of an object to resist any change in motion • The physical property that keeps an object moving after the accelerating force is gone.

20. Newton’s 2nd Law of Motion • Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

21. Acceleration • The rate at which the velocity of an object changes over time.

22. Newton’s 3rd Law of Motion • For every action there is an equal and opposite re-action.

23. Air Resistance • The force that acts to slow down any object moving through air.

24. Pulley • A pulley consists of a rope or cable that runs through a grooved wheel. • Makes work easier by changing the direction of the force • Examples – flagpole, window blinds

25. Wheel and Axle • A wheel and axle is made up of a circular object and a shaft. • Examples – doorknob, bicycle wheel

26. Lever • A lever is a stiff bar rotating around a fixed point called a fulcrum. • Makes work easier by changing the direction of a force. • Examples – hammer, shovel

27. Inclined Plane • An inclined plane consists of a flat surface with one end higher than the other. • Examples – wheelchair ramp, playground slide

28. Screw • An incline planed wrapped around a center rod • Examples – base of jar lid, light bulb base

29. Wedge • A wedge is two inclined planes placed back to back • Examples – knife, axe, fork, nail, doorstop