A particle moves in space along the path $z = ax^3 + by^2$ in such a way that $\frac{dx}{dt} = c = \frac{dy}{dt}.$ Where $a, b$ and $c$ are contants. The acceleration of the particle is
$(6ac^2x + 2bc^2 ) \, \widehat k$
$(2ax^2 + 6by^2 ) \, \widehat k$
$(4bc^2x + 3ac^2 )\, \widehat k$
$(bc^2x + 2by) \, \widehat k$
The velocity- time graph of a body falling from rest under gravity and rebounding from a solid surface is represented by which of the following graphs?
The acceleration of a particle which moves along the positive $x-$axis varies with its position as shown. If the velocity of the particle is $0.8 m/s$ at $x = 0$ , the velocity of the particle at $x = 1.4$ is(in $m/s$)