Linear motion

Linear motion, also called rectilinear motion, is one-dimensional <a href="/facts/Motion_(physics)/dCnP7MlB">motion</a> along a <a href="/facts/Line_(mathematics)/gJqsr4Gj">straight line</a>, and can therefore be described mathematically using only one spatial <a href="/facts/Dimension/0ktmUyac">dimension</a>. The linear motion can be of two types: uniform linear motion, with constant <a href="/facts/Velocity/Q3o1LVDe">velocity</a> (zero <a href="/facts/Acceleration/UVDmjYvR">acceleration</a>); and non-uniform linear motion, with variable velocity (non-zero acceleration). The motion of a <a href="/facts/Point_particle/4MPToN8W">particle</a> (a point-like object) along a line can be described by its position 
 
 
 
 x
 
 
 {\displaystyle x}
 
, which <a href="/facts/Time-variant_system/sDEWpWGg">varies</a> with 
 
 
 
 t
 
 
 {\displaystyle t}
 
 (time). An example of linear motion is an athlete running a <a href="/facts/100-meter_dash/fhxY7E6F">100-meter dash</a> along a straight track.
Linear motion is the most basic of all motion. According to <a href="/facts/Newton%27s_first_law_of_motion/XKzGTXK1">Newton's first law of motion</a>, objects that do not experience any <a href="/facts/Net_force/XzbmueXk">net force</a> will continue to move in a straight line with a constant velocity until they are subjected to a net force. Under everyday circumstances, external forces such as <a href="/facts/Gravity/bqAN7DdQ">gravity</a> and <a href="/facts/Friction/d0108Rpu">friction</a> can cause an object to change the direction of its motion, so that its motion cannot be described as linear.
One may compare linear motion to general motion. In general motion, a particle's position and velocity are described by <a href="/facts/Vector_(geometric)/bCLrdksy">vectors</a>, which have a magnitude and direction. In linear motion, the directions of all the vectors describing the system are equal and constant which means the objects move along the same axis and do not change direction. The analysis of such systems may therefore be simplified by neglecting the direction components of the vectors involved and dealing only with the <a href="/facts/Magnitude_(mathematics)/KCn9PoF0">magnitude</a>.

Linear motion open-in-new

Linear motion