a particle moves in a circle of radius 21/22m

with a constant velocity of 1m/s.

find

magnitude of average velocity

and

magnitude of average acceleration in 2 s

first of all if a particle is moving in a circle then its velocity cant be constant....so in ques there should be constant speed instead of constant velocity....

avg velocity = displacement/time

from v you can calculate omega...and then theta i.e. angular displacement

then draw a circle and make a triangle inside it with two sides as radius and third as straight line obtained by joining the arc which is formed due to displacement...

theta will be 44/21 radian thus theta/2 = 22/21 radian which can be also written as pie/3....now use the trigonometry inside the triangle to find the length of the strght line formed due to arc i.e. displacement and it will be (21*underroot3)/22 and thus divide it by time i.e 2 sec and u will get the answer i.e. (21*underroot3)/44....

and for avg acceleration = change in velocity/time

firstly calculate change in velocity i.e. (underroot3) and theen divide it by time.... 

Approved