The velocity-time graph of the particle moving along a straight line is shown. The rate of acceleration and deceleration is constant and it is equal to $5{ \mathrm{ms}}^{-2}$. If the average velocity during the motion is $20{ \mathrm{ms}}^{-1}$, then the value of $t$ is

The figure shows the $v-t$ graph of a particle moving in straight line. Find the time when particle returns to the starting point.

In a projectile motion assuming no air drag let $t_{0A}=t_1$ and $t_{AB}=t_2$. The horizontal displacement from $O$ to $A$ is $R_1$ and from $A$ to $B$ is $R_2$. Maximum height is $H$ and time of flight is $T$. Now if air drag is to be considered, then choose the correct alternative(s).

A gun is set up in such a way that the muzzle is at ground level as in figure. The hoop $A$ is located at a horizontal distance $40\mathrm{m}$ from the muzzle and is $50\mathrm{m}$ above the ground level. Shell is fired with initial horizontal component of velocity as $40{\mathrm{ms}}^{-1}$. Which of the following is/ are correct?