1. A circular billboard with a diameter of 4 m is exposed to the wind. Estimate the total force exerted on the structure by a wind that has a direction normal to the structure and a speed of 20 m/s....

1. A circular billboard with a diameter of 4 m is exposed to the wind. Estimate the total force exerted on the structure by a wind that has a direction normal to the structure and a speed of 20 m/s. Assume T = 10°C and p = 101 kPa absolute. Use Table 11.1 in §11.3.

2. Consider a large rock situated at the bottom of a river and acted on by a strong current. Estimate a typical speed of the current that will cause the rock to move downstream along the bottom of the river. List and justify all assumptions. Show all calculations and work in SI units. Use Table 11.1 in §11.3.