Box Displacement Angle
1. **State the problem:** A box is dropped from an aeroplane 2000 m high, moving horizontally at 100 m/s. It takes 20.2 s to hit the ground. We need to find the angle between the horizontal and the displacement vector of the box from the release point.
2. **Identify known values:**
- Initial horizontal velocity, $v_x = 100$ m/s
- Time of flight, $t = 20.2$ s
- Vertical displacement (height), $h = 2000$ m
3. **Calculate horizontal displacement:**
Since horizontal velocity is constant,
$$x = v_x \times t = 100 \times 20.2 = 2020 \text{ m}$$
4. **Calculate vertical displacement:**
The box falls 2000 m vertically downward.
5. **Calculate the angle of displacement:**
The displacement vector has components $x = 2020$ m (horizontal) and $y = 2000$ m (vertical downward).
The angle $\theta$ between the horizontal and the displacement vector is given by
$$\theta = \tan^{-1}\left(\frac{\text{vertical displacement}}{\text{horizontal displacement}}\right) = \tan^{-1}\left(\frac{2000}{2020}\right)$$
6. **Evaluate the angle:**
$$\theta = \tan^{-1}(0.9901) \approx 44.5^\circ$$
7. **Final answer:**
The angle between the horizontal and the displacement of the box is approximately **44.5 degrees** to 3 significant figures.