Velocity and acceleration of a particle at some instant of time are v = (2i-j+2k ) m/s and a = (i + 6j-k) m/s2 . then the speed of the particle is ....................... at a rate of ............................ m/s2.
(a)increasing , 2
(b)decreasing , 2
(c)increasing , 4
(d)decreasing , 4
