$A$ balloon is at a height of $81\, m$ and is ascending upwards with a velocity of $12\, m/s$. $A$ body of $2\, kg$ weight is dropped from it. If $g = 10\, m/s^2$,the body will reach the surface of the earth in ......... $s$.

$A$ player throws a ball upwards with an initial speed of $29.4\; m s^{-1}$. Choose the $x=0\; m$ and $t=0\; s$ to be the location and time of the ball at its highest point. Let the vertically downward direction be the positive direction of the $x$-axis. Determine the signs of position,velocity,and acceleration of the ball during its upward and downward motion.

$A$ ball is thrown vertically upwards with a velocity of $15 \ m/s$. To what maximum height will it reach? (Take $g = 10 \ m/s^2$)

Which of the following statements is correct?

Can a particle moving in a straight line have zero velocity and non-zero acceleration at any instant? Give an example.

$A$ body falls freely for $10 \ s$. What is its average velocity during this journey (in $m/s$)? (Take $g = 10 \ m/s^2$)