Term | Definition |
Motion | When an object changes position over time relative to a reference point |
Reference Point | A moving or nonmoving object used to see a changing position (Ex. earths surface, trees, buildings |
Speed | The distance traveled divided by the time taken to travel that distance |
How to determine speed | Total distance / Total time |
Velocity | The speed of an object in a particular direction |
Difference between speed and velocity? | Direction (N, S, E, W) |
Acceleration | The rate at which velocity changes (speed, direction or both) over time |
Difference between velocity and acceleration | How fast the change (speed or direction) is |
Force | A push or a pull exerted on an object in order to change the motion of the object. Has both size and direction. |
Net Force | The combination of all of the forces acting on an object |
How can net force (same direction) be determined? | Add the forces |
How can net force (opposite direction) be determined? | Subtract the smaller force from the larger force |
Balanced Force | Net Force of 0 N, will not cause a change in the motion of a moving object. Does not cause a nonmoving object to start moving |
Unbalanced Force | Net Force not equal to 0 N. will product a change in motion. Necessary to cause a nonmoving object to start moving |
Friction | A force that opposes motion between two surfaces that are in contact |
Kinetic Friction | Friction between two moving objects (Applying brakes on a bike or write with a pencil) |
Static Friction | When a force is applied to an object but does not cause the object to move (ex box on a table) |
How is friction harmful? | Causes holes in your socks, top soil to blow away |
How is friction helpful? | Pencils to write on paper, keeps us from slipping and falling when we walk |
Ways to reduce friction | Use lubricants, switch from sliding to rolling kinetic friction, make surfaces smoother |
Ways to increase friction | Make surfaces rougher, increase the force pushing the surfaces together |
Gravity | A force of attraction between objects that is due to their masses |
How can you over come gravity? | You must apply forces |
Law of Universal Gravitation: Part 1 | Gravitational force increases as mass increases |
Law of Universal Gravitation: Part 2 | Gravitational force decreases as distance increases |
Difference between mass and weight | The mass of an object does not change |
Weight | A measure of the gravitational force exerts on an object (its value can change with the location of the object in the universe) |
Mass | A measure of the amount of matter in an object |