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matter and motion
| Question | Answer |
|---|---|
| What is an object that appears to stay in place? | reference point |
| What is an objects change of position relative to its reference point? | motion |
| What are some examples of reference directions? | north,east,south,west |
| What is the unit for speed? | meters per second |
| What is the average speed formula? | distance/time |
| What must velocity include? | a reference point |
| An objects velocity is constant only if its _______ and ______ changes | speed and directions |
| What is the rate at which velocity changes? | acceleration |
| What changes when speed changes? | velocity |
| What is an increase in velocity? | positive acceleration |
| What is a decrease in velocity? | negative acceleration |
| What unit is acceleration expressed in? | meters per second |
| What is a push or a pull? | a force |
| What two things do forces have? | size and direction |
| What is a change in an objects motion caused by? | a force |
| What is the unit that force is expressed in? | newtons |
| What is the combination of all the forces acting in an object? | net force |
| When two forces act in opposite directions, what direction determines the net force? | the larger one |
| When the forces on an object produce a net force of 0N, the forces are ________ | balanced |
| When the net force is not at 0N, the forces on the object are _________ | unbalanced |
| Unbalanced forces produce a change in what two things? | motion and direction |
| Unbalanced forces are necessary to make a nonmoving object start doing what? | moving |
| What is the force that opposes motion between two surfaces that are in contact? | friction |
| The surface of an object has to be ______ to have friction | rough |
| Friction depends on what two things? | 1.pushing the surfaces together 2. the roughness of the object |
| Does changing the amount of surfaces that come in contact effect the amount of friction? | NO |
| What are the two types of friction? | Kinetic friction and static friction |
| What has a larger force? (kinetic or static friction) | kinetic friction |
| What are lubricants? | substances that reduce the amount of friction on an object |
| You can increase a force by...? | pushing the surfaces together |