Three particles, located initially on the vertices of an equilateral triangle of side $L,$ start moving with a constant tangential acceleration towards each other in a cyclic manner, forming spiral loci that coverage at the centroid of the triangle. The length of one such spiral locus will be
The length of second's hand in watch is $1 \,cm.$ The change in velocity of its tip in $15$ seconds is
The co-ordinates of a particle moving in $x-y$ plane are given by : $\mathrm{x}=2+4 \mathrm{t}, \mathrm{y}=3 \mathrm{t}+8 \mathrm{t}^2 .$ The motion of the particle is :