Three girls skating on a circular ice ground of radius $200 \;m$ start from a point $P$ on the edge of the ground and reach a point $Q$ diametrically opposite to $P$ following different paths as shown in Figure. What is the magnitude of the displacement vector for each ? For which girl is this equal to the actual length of path skate ?
Displacement is given by the minimum distance between the initial and final positions of a particle. In the given case, all the girls start from point $P$ and reach point $Q$. The magnitudes of their displacements will be equal to the diameter of the ground.
Radius of the ground $=200 \,m$ Diameter of the ground $=2 \times 200=400 \,m$
Hence, the magnitude of the displacement for each girl is $400\, m$. This is equal to the actual length of the path skated by girl $B$.
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