hi, so the material that would normally form mineral crystals does not have time to form a crystalline structure because of very rapid cooling after volcanically erupting into the air or onto the surface. Obsidian is a volcanic glass.
Answer:
The value is 
Explanation:
From the question we are told that
The operating temperature is 
The emissivity is 
The power rating is 
Generally the area is mathematically represented as

Where
is the Stefan Boltzmann constant with value

So


Answer:
Energy due to air resistance = 31.8 Joules
Explanation:
According to the law of conservation of energy, energy can neither be created nor destroyed but can be transformed from one form to another
Kinetic Energy + Energy due to air resistance = Potential energy..........(1)
If there is no energy loss due to air resistance, potential energy = kinetic energy
mass, m = 1.5 kg
height, h = 4.0 m
speed, v = 6 m/s
Kinetic energy = 0.5 mv²
Kinetic energy = 0.5 * 1.5 * 6²
Kinetic energy = 27 Joules
Potential Energy = mgh
Potential energy = 1.5 * 9.8 * 4
Potential energy = 58.8 Joules
From equation (1)
27 + Energy due to air resistance = 58.8
Energy due to air resistance = 58.8 - 27
Energy due to air resistance = 31.8 Joules
A new jxo rib is excellent is.