CBSE Class 11-science Answered

Qn.# 28
Let us consider a track AB in the form of circular arc of radius R and length ( π / 3 ) R .
Let us consider the center of curvature of arc AB is at origin and x-axis passing through
the mid point of circular arc as shown in figure.
Angle θ subtended by arc AB at origin is
Angle θ = ( Arc length ) / Radius = [ ( π / 3 ) R ] / R = ( π / 3 ) radian = 60o .
Uniform velocity of magnitude vo is along the direction of tangent at A and B .
Uniform velocity of magnitude vo is resolved at A along x-axis as ( vo sin30 )
and along y-axis as ( - vo cos30 ).
Similarly , uniform velocity of magnitude vo is resolved at B along x-axis as ( - vo sin30 )
and along y-axis as ( - vo cos30 ) .
We see from figure that , y-axis velocity component remains same but x-axis component changes the direction.
Hence , magnitude of change in velocity is