The change of color. Each color has a different wavelength therefore a different frequency.
Most clouds form in the atmosphere when moist air rises expands and cool to the dew point. When the air above reaches its saturation point, the water vapor is attracted to dust particles which when they accumulate the hold on tho each other and form clouds. Evaporation and condensation is what causes saturation above. When the clouds become heavy enough with moisture, the water then fall to earth as rain. <span />
Answer:
4v/3
Explanation:
Assume elastic collision by the law of momentum conservation:

where v is the original speed of car 1, v1 is the final speed of car 1 and v2 is final speed of car 2. m1 and m2 are masses of car 1 and car 2, respectively
Substitute 

Divide both side by
, then multiply by 6 we have



So the final speed of the second car is 4/3 of the first car original speed
The train would need the greatest amount of force due to weight! If you think of it, a baseball won't need much force to stop it, but if you have a heavy train, it will need excessive force to stop the train. The answer would be #3
I hope this answer helps!
Sorry if it doesn't make sense, as I don't know that much about physics! I am just thinking of what makes sense.
Answer:
The force F is created by the reaction of the Earth to the thrust of the rods, whereby the thrust is created by a force of action and reaction.
Explanation:
To answer this question, let's write Newton's second law of the two axes
Y Axis
Fy + N - W = 0
Fy + N = W
X axis
Fx - fr = 0
Fx = fr
The force F is created by the reaction of the Earth to the thrust of the rods, whereby the thrust is created by a force of action and reaction.
The direction of this force is along the length of the rods that are in an Angle, where the x and y components of the force come from
In general this force is small because the rubbing of the skis is small