Question

A particle is moving in a circle of radius R as shown in the Fig.
a.What is its displacement when it covers (i) half the circle, (ii) full circle?
b.What is its distance when it covers(i) half the circle and (ii) full circle?

Answer 1

Displacement is the vector drawn from the initial position to the final position, and its magnitude is equal to the shortest distance between the initial and final positions.
i. Hence, displacement is equal to the diameter of the circle = 2 R.
ii. As initial and final positions are same, i.e., displacement will be zero.
b; Distance is the length of the path travelled by the particle. Hence, distance traveled in case (i) will be equal to $\pi R$. Hence, distance traveled in case (ii) will be equal to 2$\pi R$