1. 
motion  The natural force produced by a magnetic field.   A measure of the force of gravity on an object.   A device used for measuring weight.   A change in the position or place of something over time in comparison to a reference point. 


2. 
friction  A unit that is a measure of force.   The unit of work in the metric system.   Energy in the form of a push or a pull.   A force that opposes motion between two surfaces that are touching. 


3. 
work  A measure of how fast something moves over a distance.   A measure of the amount of force needed to move an object a certain distance.   The rate at which velocity changes.   A measurement of the motion of something. This is equal to the product of the moving object's mass times its velocity. 


4. 
inertia  A device used for measuring mass.   A force that pulls objects towards each other.   A measure of both the speed and direction of a moving object.   The tendency of an object to resist a change in motion. 


5. 
weight  The amount of matter that an object has.   A measure of the force of gravity on an object.   A force that opposes motion between two surfaces that are touching.   A measure of the amount of force needed to move an object a certain distance. 


6. 
joule  A measure of how fast something moves over a distance.   The natural force produced by a magnetic field.   A device used for measuring weight.   The unit of work in the metric system. 


7. 
mass  A measure of the force of gravity on an object.   The rate at which velocity changes.   The amount of matter that an object has.   A force that pulls objects towards each other. 


8. 
balance  A measure of both the speed and direction of a moving object.   A measure of the amount of force needed to move an object a certain distance.   A device used for measuring mass.   A change in the position or place of something over time in comparison to a reference point. 


9. 
magnetism  The natural force produced by a magnetic field.   A force that opposes motion between two surfaces that are touching.   A device used for measuring mass.   A unit that is a measure of force. 


10. 
spring scale  Energy in the form of a push or a pull.   A device used for measuring weight.   The unit of work in the metric system.   The tendency of an object to resist a change in motion. 


11. 
acceleration  Energy in the form of a push or a pull.   A measurement of the motion of something. This is equal to the product of the moving object's mass times its velocity.   The unit of work in the metric system.   The rate at which velocity changes. 


12. 
velocity  The rate at which velocity changes.   A measure of both the speed and direction of a moving object.   A measure of how fast something moves over a distance.   A force that opposes motion between two surfaces that are touching. 

