If a body is moving with a constant velocity its acceleration is (zero, changing).

_____ is the distance traversed by a body in a particular direction in unit time. 

(stationary, zero, changing, constant, displacement, velocity, speed, acceleration, stationary but not zero, increases)

Observe the figure and answer the questions.

Sachin and Sameer started on a motorbike from place A, took the turn at B, did a task at C, travelled by the route CD to D and then went on to E. Altogether, they took one hour for this journey. Find out the actual distance traversed by them and the displacement from A to E. From this, deduce their speed. What was their velocity from A to E in the direction AE? Can this velocity be called average velocity?

A ball is rolling from A to D on a flat and smooth surface. Its speed is $2 \mathrm{cm}/\mathrm{s}$. On reaching B, it was pushed continuously up to C. On reaching D from C, its speed had become $4 \mathrm{cm}/\mathrm{s}$. It took $2$ seconds for it to go from B to C. What is the acceleration of the ball as it goes from B to C?