Force, mass and acceleration. 

 - Videocassette (VHS)(ca. 25 min.) : sd., b&w, 1/2 in. 
<br/><br/> Explains Newton's first law of motion, that an object will remain in a state of rest, or of uniform motion in a straight line, unless acted upon by an external resultant force. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Acceleration (Mechanics)--Study and teaching.<br/>Mass (Physics)--Study and teaching.<br/>Force and energy--Study and teaching.