Answer: friction is used when 2 and 2 things mix and come together but normally friction slows things down but when buttering a pan it doesnt slow down
Answer:
Differences
microscopic refers to substances visible to the naked eye
macroscopic are substances invisible to naked eye
Similarities
both refer to different scales that are useful to determining the size to different compounds.
Explanation:
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Answer:
Therefore the ratio of diameter of the copper to that of the tungsten is

Explanation:
Resistance: Resistance is defined to the ratio of voltage to the electricity.
The resistance of a wire is
- directly proportional to its length i.e

- inversely proportional to its cross section area i.e

Therefore

ρ is the resistivity.
The unit of resistance is ohm (Ω).
The resistivity of copper(ρ₁) is 1.68×10⁻⁸ ohm-m
The resistivity of tungsten(ρ₂) is 5.6×10⁻⁸ ohm-m
For copper:


......(1)
Again for tungsten:

........(2)
Given that
and 
Dividing the equation (1) and (2)

[since
and
]



Therefore the ratio of diameter of the copper to that of the tungsten is

Velocity = Frequency x Wavelength
= 18 x 13 = 234 mm/s