Usually, the forces that start the oscillation of buildings are the wind and microearthquakes.
Answer:

Given:
Mass (m) = 3.0 kg
Uniform speed (v) = 20 m/s
Length of string (r) = 40 cm = 0.4 m
To Find:
Tension in the string (T)
Explanation:
Tension (T) is the string will be equal to centripetal force (
).

Substituting value of m, v & r in the equation:


Tension in the string (T) = 3 kN
Drift velocity is equal to displacement of the moving object per unit time. The SI unit for displacement is meters while that of time is second. Hence the derived SI unit of velocity is meter per second. This also applies to electron mobility which relates to the displacement per unit time of a moving electron
Complete Question
An oil tanker has collided with a smaller vessel, resulting in an oil spill in a large, calm-water bay of the ocean. You are investigating the environmental effects of the accident and need to know the area of the spill. The tanker captain informs you that 18000 liters of oil have escaped and that the oil has an index of refraction of n = 1.1. The index of refraction of the ocean water is 1.33. From the deck of your ship you note that in the sunlight the oil slick appears to be blue. A spectroscope confirms that the dominant wavelength from the surface of the spill is 485 nm. Assuming a uniform thickness, what is the largest total area oil slick
Answer:
The largest total area of the oil slick 
Explanation:
From the question we are told that
The volume of oil the escaped is 
The refractive index of oil is 
The refractive index of water is 
The wavelength of the light is 
Generally the thickness of the oil for condition of constructive interference between the oil and the water is mathematically represented as

Where is the order of interference of the light and it value ranges from 1, 2, 3,...n
It is usually take as 1 unless stated otherwise by the question
substituting value
The are can be mathematically evaluated as

Substituting values

