Velocity-time graph for a car is semicircle as shown here. Which of the following is correct :
Car must move in circular path.
Acceleration of car is never zero.
Mean speed of the particle is $\pi /4 \,\,m/s$.
The car makes a turn once during its motion.
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 :
$Assertion$ : If a body is thrown upwards, the distance covered by it in the last second of upward motion is about $5\, m$ irrespective of its initial speed
$Reason$ : The distance covered in the last second of upward motion is equal to that covered in the first second of downward motion when the particle is dropped.
Two boys are standing at the ends $A$ and $B$ of a ground where $AB = a$. The boy at $B$ starts running in a direction perpendicular to $AB$ with velocity ${v_1}.$ The boy at $A$ starts running simultaneously with velocity $v$ and catches the other boy in a time $t$, where $t$ is