Dipesh Rawat
Last Activity: 6 Years ago
(C)7
Th path of the particle is shown by bold line segments and arcs . It is given that on the circle c_k of radius k cm the particle moves k cm. Therefore angular displacement on kth circle is given by the circle already drawn in the previous answer . Therefore:
Theta=k/k radians or 1 radian.
Thus,angular displacement on eaxh circle is 1 radian.
If the particle crosses the x-axis for the first time on circle c_n then;
Total angular displacement=n radians
As the particle crosses the positive direction of
the X axis for the first time on the nth circle c_n.
total angular displacement>2πradians
Thus n>2π and so n= 7
(C)is the correct answer