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 |