Force and motion
This document discusses motion and forces. It covers topics like speed and velocity, balanced and unbalanced forces, friction, Newton's laws of motion, and more. Speed describes the rate of change in an object's position over time, while velocity also includes direction. Balanced forces are equal and opposite, resulting in no net force and no acceleration. Unbalanced forces cause a change in velocity or acceleration. Friction opposes motion between surfaces and depends on factors like the types of surfaces and force between them. Newton's laws state that an object at rest or in motion will remain so unless acted upon by an unbalanced force, more force results in more acceleration proportional to mass, and for every action there is an equal and opposite reaction
Force and motion
- 2. Speed & Velocity • Speed - the rate of change in position over time (distance/time) • Instantaneous speed • Average speed • How is velocity different from speed? Velocity describes both speed and direction
- 3. Change in Velocity What makes an object change velocity?
- 4. Force • Push or Pull • Forces can cause a change in velocity • Examples: Gravity Magnetism Friction
- 5. Balanced Forces Forces that – act on the same object – are opposite in direction – are equal in size
- 6. Balanced Forces Book on table 1. Weight of the book is downward force caused by gravity 2. Table pushes back with an equal and opposite force Net force is zero
- 7. Unbalanced Forces Forces that are NOT opposite and equal What do they cause? CHANGE IN VELOCITY ACCELERATION
- 8. Friction Force that opposes motion between 2 surfaces Depends on the: • types of surfaces • force between the surfaces
- 9. Types of Friction • Static Friction: (Couch Potato) – Force between objects at rest • Sliding Friction: (Ice skating) – Solid surfaces slide over each other • Rolling Friction: (Rollerblading) – An object rolls over a surface. • Fluid friction: (Submarine) – An object moves through a fluid
- 10. Friction Friction is greater... –between rough surfaces –when there’s greater force between surfaces (such as more weight)
- 11. Lubricant Changes sliding friction into fluid friction
- 12. Friction Is friction always bad?
- 13. Gravity The attractive force between all objects in the universe
- 14. Acceleration of Gravity Near the surface of the earth the acceleration due to gravity is 9.8 m/s/s
- 15. Newton’s 1 Law st An object at rest remains at rest and an object in motion will continue moving at a constant velocity unless acted on by unbalanced forces.
- 17. Newton’s 1 Law st INERTIA • tendency of an object to resist any change in its motion • increases as mass increases
- 18. Newton‘s 2 nd Law If more force is applied, an object will be accelerated _____ more
- 19. Newton’s 2 nd Law • More force means more acceleration • More mass means less acceleration Force = mass X acceleration F = ma
- 20. Newton’s 3 rd Law For every action, there is an equal and opposite reaction. Forces occur only in pairs – Act on different objects – Equal and opposite
- 21. Newton’s 3 rd Law The hammer exerts a force on the nail to the right. The nail exerts an equal but opposite force on the hammer to the left.
- 22. Momentum
- 23. Terminal Velocity The final speed of a falling object.
- 24. Terminal Velocity Air resistance is offsetting the the weight of the object
- 26. Forces End
- 27. Force Aristotle's idea: For an object to move at a constant speed, a constant force must be applied.
- 28. Force Newton’s idea: An object moving at a constant speed will continue at that speed without additional force being applied.
- 29. Balanced Forces