Answer:
If a star is moving toward Earth, its light waves appear to be squeezed together. The decreasing distance between Earth and the star effectively shortens the wavelength of the starlight received by Earth. This shifts the star's spectral lines toward the blue end of the spectrum.
Explanation:
Answer:
The rate at which velocity changes.
Explanation:
Acceleration is when motion changes, it is the rate at which velocity changes.
Within a single medium, the product of (wavelength) x (frequency)
is always the same number, for all waves. (It's the wave-speed.)
This means that longer wavelengths must have lower frequencies,
and shorter wavelengths must have higher frequencies, in order for
the product to always come out to be the same.
Disease
Lack of natural reourses
war
asteroid
Polution.
Answer:
F2 = 4.5N
Explanation:
This problem involves the application of newton's second law of motion we would treat both boxes as a composite body, combining their masses. The net force (the sum of all forces acting on the boxes) causes the mass M (both boxes) to move with an acceleration a. Three forces act on the boxes, F and the two frictional forces.
So
F – f1 – f2 = Ma
M = m1 +m2
Given m1 = 1kg and m2 = 3kg, F = 12N, f1 = 2N, f2 = 4N.
The frictional forces have a negative sign because they oppose the direction of motion.
So
12 - 2 - 4 = (1 +3)×a
6 = 4a
a = 6/4 = 1.5m/s²
Each of the boxes moves the same acceleration a = 1.5m/s²
So the force on the right box is F2 = m2a = 3×1.5 = 4.5N
