A stone falls from rest. The distance covered by it in the last second of its motion is equal to the distance covered in the first three seconds. What is the height from which the stone was dropped? [Take $g=10 \mathrm{m} {\mathrm{s}}^{–2}$]

The acceleration-time graph of a particle moving along a straight line is as shown in the figure. In what time will the particle acquire its initial velocity?

Each of three graphs represents acceleration versus time for an object that already has a positive velocity at time $t_1$. Which graphs show an object whose speed is increasing for the entire time interval between $t_1$ and $t_2$?

A particle obeys the following $v-t$ graph as shown. The average velocity over $30 \mathrm{s}$ is