Define velocity as the rate at which displacement changes with time.
In an experiment, two objects A and B are released from the side of a building, as shown in Fig. 1.1. Object A is let go from rest at a height of $10.0\,\text{m}$ above level ground. Object B is launched with an initial upward velocity of $3.0\,\text{m s}^{-1}$ from a height $h$ above the ground. Both objects require the same time to reach the ground and they do not collide. Air resistance is negligible. Calculate $h$.
In a second experiment, object B is let go from the same height as in (b) with a speed of $6.0\,\text{m s}^{-1}$ at an angle of $60^{\circ}$ to the vertical, as shown in Fig. 1.2. State and explain whether the time taken for object B to reach the ground is less than, the same as, or greater than in the first experiment.
Using energy ideas, state and explain whether the speed of object B on reaching the ground is less than, the same as, or greater than in the first experiment.