If a freely falling body travels in the last second a distance equal to the distance travelled by it in the first three seconds,the time of the travel is ........ $sec$.

$A$ ball is projected vertically up from the ground. Boy $A$, standing at the window of the first floor of a nearby building, observes that the time interval between the ball crossing him while going up and the ball crossing him while going down is $2 \ s$. Another boy $B$, standing on the second floor, notices the time interval between the ball passing him twice, during up and down motion, is $1 \ s$. Calculate the difference between the vertical positions of boy $B$ and boy $A$. (Assume $g = 10 \ m \ s^{-2}$) (in $m$)

Two balls are released from the same position at a height of $500 \ m$ above the ground, one after the other, with an interval of $1 \ s$. What is the distance between the two balls when the first ball hits the ground (in $m$)? (Acceleration due to gravity $g = 10 \ m/s^2$)

If a ball is thrown vertically upwards with speed $u$,the distance covered during the last $t$ seconds of its ascent is

If a ball is thrown at a velocity of $45 \,m/s$ in the vertical upward direction,what would be the velocity profile as a function of height? (Assume $g = 10 \,m/s^2$)

$A$ body is thrown vertically upwards with a velocity of $35 \ m/s$ from the ground. The ratio of the speeds of the body at times $3 \ s$ and $4 \ s$ of its motion is (Acceleration due to gravity $= 10 \ m/s^2$)