Always Remember 

For uniform rectilinear motion, 

i.e., for an object moving with constant velocity along a straight line  

1.  The average and instantaneous velocities are equal. 

2.  The average and instantaneous speeds are the same and are equal to the magnitude of the velocity. 

For nonuniform rectilinear motion 

1.  The average and instantaneous velocities are different. 

2.  The average and instantaneous speeds are different. 

3.  The average speed will be different from the magnitude of average velocity

For uniform acceleration, for a rectilinear motion: 

1. Velocity-time graph is linear. 

2. The area under the velocity-time graph between two instants of time t1 and t2 gives the displacement of the object during that time interval.  

3. The slope of the velocity-time graph is the acceleration of the object.

For nonuniform acceleration in a rectilinear motion: 

1. Velocity-time graph is nonlinear.  

2. The area under the velocity-time graph between two instants of time t1 and t2 gives the displacement of the object during that time interval. 

3. The instantaneous acceleration of the object at a given time is equal to the slope of the tangent to the curve at that point. 

While using the concept of area under the curve, the origin of the velocity axis (for v-t graph) must be zero.

Motion in two dimensions can be resolved into two independent motions in mutually perpendicular directions.