The change in pitch of a train's horn as it passes while you are
standing still can be described by the Doppler effect, but that
doesn't explain it.
Answer:

Explanation:
As we know that the that the Astronaut dropped a stone on the surface of the planet takes 0.420 s to fall a distance of d = 1.90 m
so we will have



now we know that the acceleration due to gravity is given as

so we will have


<h2>Answer: in a gaseous state
</h2>
The average kinetic energy of the water molecules is greater in its gaseous state (in the form of water steam).
This is because in the gaseous state the water molecules are well separated from each other and can move freely in all the available space they have; because there are no cohesion forces that bond them.
In contrast to the liquid and solid state, in which the molecules have less movement.
Answer:
The activation energy for this reaction, Ea = 159.98 kJ/mol
Explanation:
Using the Arrhenius equation as:

Where, Ea is the activation energy.
R is the gas constant having value 8.314 J/K.mol
K₂ and K₁ are the rate constants
T₂ and T₁ are the temperature values in kelvin.
Given:
K₂ = 8.66×10⁻⁷ s⁻¹ , T₂ = 425 K
K₁ = 3.61×10⁻¹⁵ s⁻¹ , T₁ = 298 K
Applying in the equation as:

Solving for Ea as:
Ea = 159982.23 J /mol
1 J/mol = 10⁻³ kJ/mol
Ea = 159.98 kJ/mol