Acceleration-time graph for a particle is given in figure. If it starts motion at $t=0$, distance travelled in $3 \,s$ will be ........... $m$
Read each statement below carefully and state with reasons and examples, if it is true or false
A particle in one-dimensional motion
$(a)$ with zero speed at an instant may have non-zero acceleration at that instant
$(b)$ with zero speed may have non-zero velocity.
$(c)$ with constant speed must have zero acceleration.
$(d)$ with positive value of acceleration must be speeding up.
A particle initially at rest starts moving from reference point. $\mathrm{x}=0$ along $\mathrm{x}$-axis, with velocity $v$ that varies as $v=4 \sqrt{\mathrm{x} m} / \mathrm{s}$. The acceleration of the particle is __________$ \mathrm{ms}^{-2}$.