An arachnid has eight legs.
Answer:
c. they travel through all forms of matter
Explanation:
Convection is the transfer of heat from one place to another via the movement of fluids. It happens from higher energy level to lower energy level to bring equilibrium to the system.
For vertical set up , if the hot water is places on top of cold water, direction of convection will be from top to bottom. So, gravity can play a role in increasing the rate of flow of energy. if the cold water is places on top of hot water, direction of convection will be from bottom to top. So, gravity can play a role in decreasing the rate of flow of energy.
for Horizontal set up, when hot and cold water are placed side by side, gravity will not playing a role in the flow of energy.So, the position of hot or cold water would not matter.
Explanation:
It is given that,
The thinnest soap film appears black when illuminated with light with a wavelength of 535 nm, 
Refractive index, 
We need to find the thickness of soap film. The soap film appear black means there is an destructive interference. The condition for destructive interference is given by :

t = thickness of film
m = 0,1,2....
= refractive index


For thinnest thickness, m = 1


Hence, this is the required solution.
Answer: work done = 64,000J or 64KJ.
Explanation:
Work is said to be done if a force applied makes the object to move through a distance in the direction of the applied force. Work is the product of force and perpendicular distance in the direction of the applied force. It is represented by W, measured in Joules(J) and a scalar quantity.
Thus, work done(J)= force(N) × distance(m)
From the the question,
applied force= 1600N
distance=40m
Therefore, work= 1600 × 40
W= 64,000J
But, 1 kilojoules = 1000J
Therefore, 64,000J = 64,000 ÷ 1000
= 64KJ
Work done is 64KJ