1. Velocity and Acceleration
   When the position of a point moving on a straight line is given by , the velocity and acceleration of point at time are expressed as:
   
   The absolute value of velocity, , is called the speed of point at time , and is called the magnitude of acceleration.
   
   The sign of velocity indicates the direction of motion of point . If , the function is increasing, meaning point is moving in the positive direction. If , the function is decreasing, so point is moving in the negative direction. When , the motion either stops or changes direction.
   
   
   
2. Rate of Change with Respect to Time
   When a physical object has a length , area , or volume at time , and after a time interval these quantities change by , , and respectively, the rate of change of length, area, and volume at time are given as:
1. Rate of change of length :
2. Rate of change of area :
3. Rate of change of volume :