21) Acceleration from D to E: 
22) The acceleration of the bus from D to E is 
Explanation:
21)
The acceleration of an object is equal to the rate of change of velocity of the object. Mathematically:

where
u is the initial velocity
v is the final velocity
t is the time elapsed
In this problem, we want to measure the acceleration of the bus from point D to point E. We have:
- Initial velocity at point D: u = 0
- Final velocity at point E: v = 5 m/s
- Time elapsed from D to E: t = 21 - 16 = 5 s
Therefore, the acceleration between D and E is

22) This question is the same as 21), so the result is the same.
Learn more about acceleration:
brainly.com/question/9527152
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Answer:
and 
Explanation:
The wavelength of a visible light is 727.3 nm.

The formula is as follows :

f is the frequency of the visible light

Energy of a photon is given by :
E = hf, h is Planck's constant

Red color has a frequency of
and energy per photon is
.
Before we answer this question, let us first understand
what alternate hypothesis is.
The alternative hypothesis is the hypothesis which is
used in the hypothesis testing and this is opposite to the null hypothesis.
This is the test hypothesis which is usually taken to be that the observations
are the result of a real effect in an experiment.
In this case since what we want to set up is the
statistical test to see if the waves are dying down, then this means we are
trying to determine if the wave height are decreasing, so lesser than 16.4
feet. Therefore:
The alternative hypothesis would state (ANSWER)
Ha: μ less than 16.4 feet and
P-value area is on the left of the mean.
While the null hypothesis is the opposite and would state
H0: mu equals 16.4 feet
Answer:
Tangential acceleration is in the direction of velocity - along the circumference of a circle if the object is undergoing circular motion
a = (V2 - V1) / T
Radial acceleration is perpendicular to the direction of motion if the object is not moving in a straight line (perhaps along the circumference of a circle)
a = m V^2 / R = m ω^2 R where R is the radius vector of the velocity - note that the Radius vector is directed from the center of motion to the object and for circular motion would be constant in magnitude but not in direction