# Geologists place tiltmeters on the sides of volcanoes to measure the displacement of the surface as magma moves inside the volcano. Although most tiltmeters today are electronic, the traditional tiltmeter, used for decades, consisted of two or more water-filled metal cans placed some distance apart and connected by a hose. The figure(Figure 1) shows two such cans, each having a window to measure the water height. Suppose the cans are placed so that the water level in both is initially at the 5.0cm mark. A week later, the water level in can 2 is at the 6.6cm mark. Cans are 100m apart.

Q: Did can 2 move up or down relative to can 1?

A: Can 2 has moved down

Q: By what distance??????

Q: Where is the water level now in can 1?????

## To determine the distance by which can 2 moved relative to can 1, we need to compare the change in water level between the two cans.

Given that can 1 and can 2 were initially at the same water level of 5.0 cm, and a week later, the water level in can 2 is at the 6.6 cm mark, we can find the difference in water levels between can 1 and can 2.

Change in water level = Water level in can 2 - Initial water level in can 2

Change in water level = 6.6 cm - 5.0 cm

Change in water level = 1.6 cm

Therefore, can 2 moved down relative to can 1 by a distance of 1.6 cm.

To find the current water level in can 1, we need to subtract the distance by which can 2 moved from its initial water level.

Current water level in can 1 = Initial water level in can 1 - Distance moved by can 2

Current water level in can 1 = 5.0 cm - 1.6 cm

Current water level in can 1 = 3.4 cm

So, the water level in can 1 is now at the 3.4 cm mark.