By the time of its completion in 1884, the Washington Monument in the United States had a height of 169 m.

By the time of its completion in 1884, the Washington Monument in the United States had a height of 169 m. Since then, it has plunged into the ground at an average speed of 12.7 cm / year. How long does it take to level off the surface?

We bring the initial data on speed and lengths to the same units:

One meter equals 100 cm, then 169m = 169 × 100 = 16,900 cm.

The units of account will not correspond to the international system of units of SI, but the solution to this problem will be correct.

The height in this case is physically similar to distance, and the required time is the travel time.

Knowing the speed V = 12.7 cm / year and the distance S = 16 900 cm, the time t, in this case in years, is determined:

t = S: V [year];

t = 16 900: 12.7 = 1330.7 years;

Round off: 1,330.7 = 1331 years;

Answer: The Washington Monument will be leveled to the surface of the earth in 1331 from the date of its foundation in 1884.