ABSTRACT
The fundamental quantities that represent motion are time and length. In the SI unit system, the unitoftimeissecond(s),andthatoflengthismeter(m).Theunitsofvelocityandaccelerationare meterpersecond(m/s)andmeterpersecondsquared(m/s2), respectively. The standard gravitational accelerationis9.80665m/s2. To express rotation, the angle, angular velocity, and angular accelerationareused,andtheirunitsintheSIsystemareradian(rad),radianpersecond(rad/s),andradian persecondsquared(rad/s2), respectively. Degree, minute, and second have been conventionally used,whicharedenotedbythesymbols°,′,and″,respectively,and1°=π/180rad,1′=(1/60)°,and 1″ = (1/60)′. The unit of frequency is hertz (Hz); 1 Hz = 1 s−1.
