The answer would be
C. Rods and Cones
Given parameters:
Displacement = 8km
Velocity = 3.8km/h
Unknown:
time = ?
Solution:
Velocity is displacement divided by time.
Velocity = 
Displacement = velocity x time
Input the parameters:
8 = 3.8 x time
Time = 
= 2.1s
The time taken is 2.1s
Answer:
The term rotational and irrotational flow is associated withe the flow of particles in fluid.
The common example of irrrotational flow can be seen on the carriages of the Ferris wheel (giant wheel).
Explanation:
- If the fluid is rotating along its axis with the streamline flow of its particles,then this type of flow is rotational flow.
- Similarly if fluid particles do not rotate along its axis while flowing in a stream line flow then it is considered as the irrotational flow.
- In majority, if the flow of fluid is viscid then it is rotational.
- Fluid in a rotating cylinder is an example of rotating flow.
Well hydrogen would be the main element, as a process called nuclear fusion with both helium and hydrogen atoms occurs within stars. And planets are the products of dead stars that have burned through their supplies of hydrogen, helium, and carbon. Planets are a product of this.
