Position, path length and displacement
* Displacement is the change in the position of the body.
Average velocity and average speed
* Speed is a scalar whereas velocity is a vector.
* The average velocity is the ratio of the change in position or displacement and the time interval in which the displacement occurs.
* The unit of velocity is m/s or km/h.
* Average speed is the ratio of the total path length and the total time taken for the motion.
* The unit for speed is m/s or km/h.
Instantaneous velocity and speed
* When a body moves in a straight line, the magnitude of its velocity is equal to its speed.
* The velocity at an instant or instantaneous velocity is the limit of the average velocity as the time interval △t becomes infinitesimally small.
Acceleration
* Acceleration of a body is the rate of change of its velocity with time.
* The SI unit of acceleration is m/s2.
* Acceleration can be either positive or negative.
* The positive and negative signs for acceleration depend on the direction of motion and the magnitude of velocity of the body.
Kinematic equations for uniformly accelerated motion
* The v-t graph can be used to calculate the displacement of a body.
* Kinematic equation for uniform rectilinear motion is x=x0 +v(t-t0)
* Kinematic equations for uniformly accelerated rectilinear motion are:
1. V= V0 + ⍺ (t-t0)
2. (x – x0) = v0(t – t0) + 1/2 ⍺(t – t0)2
3. v2 = v02+ 2 ⍺ (x – x0)
Relative velocity
* Relative velocity is obtained by differing relative distance with respect to time.