A stone is thrown horizontally at $20\ \text{m/s}$ from the top of a cliff $45\ \text{m}$ high, as shown in the figure. Ignore air resistance and take $g = 10\ \text{m/s}^2$. The time after which its velocity makes $45^\circ$ with the horizontal, and its distance from the point of throwing at that moment, are

Fig. 1: A stone thrown horizontally at 20 m/s from the top of a cliff 45 m high, with its curved path down to the ground.