Answer:
Force, 
Explanation:
We have,
Masses of two twins are 54 kg each
They are placed at a distance of 0.02 m
It is required to find the force of gravity between them. The formula used to find the gravitational force between masses is given by :

plugging all the known values:

So, the force of gravity between them is
.
Answer: a. both reliable and valid
The parameters used to describe a particular trait or characteristic in a human behavior should be reliable and valid, in order to determine the response of the population with respect to a particular stimulus.
Answer:
1) Used in optical instruments such as telescopes.
2) Used to form mirages
Explanation:
1) Perhaps the simplest example of this is the astronomical refractor telescope with a right-angle eyepiece holder. Astro scopes mostly point at things high in the sky, but it is inconvenient to place your eye low to look up through the scope, so the light path is bent 90 degrees just before the eyepiece. This can be done with a mirror, but using a simple 45 degree prism (internal angles 45, 45, and 90 degrees) will do the 90 degree bend more efficiently.
2) So when a light pass from cold air to hot air light tends to bend from its path which is known as refraction. As the light get refracted it reaches to a point where the light tends to form 90 degree angle.
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Answer:</u></h2>
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<u>Force = kgm/s² ⟶ Newton</u>
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Explanation:</u></h2>
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According to the formula we've learnt,
- Force = mass × acceleration.
To find force in terms of base units, we must first identify the base SI units of mass & acceleration.
- Base SI unit of mass = kg (kilogram)
- Base SI unit of acceleration = m/s² (meter per second squared)
So, the base unit of force is,
- Force = mass × acceleration.
- <u>Force = kgm/s² ⟶ Newton</u>
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Hope it helps!

Answer:
Metals
Explanation:
The group of elements with few valence electrons that conducts heat and electricity is known metals. Metals are good conductors of heat and electricity. The outer electrons in metals are loosely bound to the atom and are thus able to freely move around and conduct electricity and heat.