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Chapter 9+10 Science
Motion and Forces
| Question | Answer |
|---|---|
| What is motion? | The state in which one object‘s distance from another is changing. |
| What is a reference point? | A place or object used for comparison to determine if an object is in motion. |
| What is the International System of Units | A system of measurement based on multiples of ten and on established measures of mass, length, and time. |
| What is a meter? | The basic SI unit of length. |
| What is speed? | The distance an object travels per unit of time. |
| What is average speed? | The overall rate of speed at which an object moves; calculated by dividing the total distance an object travels by the total time. |
| What is instantaneous speed? | The speed of an object at one instant of time. |
| What is velocity? | Speed in a given direction. |
| What is slope? | The steepness of a line on a graph, equal to its vertical change divided by its horizontal change. |
| What is acceleration? | The rate at which velocity changes. |
| What is a force? | A push or a pull. |
| What is a newton? | A unit of measure that equals the force required to accelerate 1 kilogram of mass at 1 meter per second per second. |
| What is net force? | The overall force on an object when all the individual forces acting on it are added together. |
| What are unbalanced forces? | Forces that produce a nonzero net force, which changes an object’s motion. |
| What are balanced forces? | Equal forces acting on an object in opposite directions. |
| What is friction? | the force that two surfaces exert on each other when they rub against each other. |
| What is static friction? | the friction that acts on objects that are not moving |
| What is sliding friction? | the friction that occurs when two objects slide over each other |
| What is rolling friction? | the friction that occurs when an object rolls over a surface |
| What is fluid friction? | the friction that occurs when an object moves through a liquid or gas |
| What is gravity? | a force that pulls objects together. |
| What is mass? | the amount of matter in an object |
| What is weight? | the force of gravity on a person or object |
| What is a free fall? | The motion of a falling object when the only force acting on it is gravity. |
| What is air resistance? | The fluid friction experienced by objects falling through the air. |
| What is terminal velocity? | The greatest velocity a falling object can achieve. |
| What is projectile? | an object that is thrown |
| What is inertia? | The tendency of an object to resist any change in its motion. |
| What is momentum? | The product of an object’s mass and velocity. |
| What is the law of conservation of momentum? | The rule that in the absence of outside forces the total momentum of objects that interact does not change. |
| When is an object in motion? | if it changes position relative to a reference point |
| How do scientists measure distance? | SI units |
| How do you know an object's speed and velocity? | speed = distance over time and velocity is speed and direction |
| How can you graph motion? | slope |
| What kind of motion does acceleration refer to? | increasing speed, decreasing speed, and changing direction |
| How is acceleration calculated? | final speed - initial speed over time |
| What graphs can be used to analyze the motion of an accelerating object? | speed and distance vs. time graphs |
| How is a force described? | by its strength and its direction |
| How are unbalanced and unbalanced forces related to an objects motion? | unbalanced forces change and balanced do not change the object's motion |
| What factors determine the strength of the friction force between two surfaces? | how hard the two surfaces push together and the types of surfaces involved |
| What factors affect the gravitational force between two objects? | mass and distance |
| Why do objects accelerate during free fall? | the force of gravity is an unbalanced force |
| What is Newton's first law of motion? | an object at rest will remain at rest and an object in motoion will remain in motion until acted upon by an unbalanced force |
| What is Newton's second law of motion? | F=ma |
| What is Newton's third law of motion? | if one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object. |
| How can you determine the momentum of an object? | mass x velocity |
| What is displacement? | how far an object has moved in relation to its starting point |
| What is an example of sliding friction? | riding a bike and you hit the brakes to stop |
| What is an example of static friction? | pushing a car |
| What is an example of rolling friction? | riding a skateboard |
| What is an example of fluid friciton? | surfing |