Average velocity and instantaneous velocity.

 

Question: a particle moves according to

      x = - t2 + 2 t +3,
      y = 0.5 t2 - 2.5 t +2.

Find its average velocity between t = 1 s and t =2 s.

 

Answer:

                                          

 


Instantaneous velocity

 

Question: a particle moves according to

      x = - t2 + 2 t +3,
      y = 0.5 t2 - 2.5 t +2.

Find its velocity at t = 2 s in unit-vector notation and  as a magnitude and an angle.

 

Answer:

                               


The direction of the instantaneous velocity of a particle is always tangent to the particle's path at the particle's position.

                              

Question: a particle moves along a circular path as shown in the following figure.  If 

through which quadrant the particle is moving when it is traveling (a) clockwise and counterclockwise?

                                                                     

 

Answer:

(a) Clockwise: the particle is moving in the first quadrant.  The velocity vector particle is tangent to the particle's path. The velocity vector points in the direction of the particle's motion.

       

(b) Counterclockwise: the particle is moving in the third quadrant.