Answer:
The runner's acceleration was 
Explanation:
<u>Constant Acceleration Motion</u>
It's a type of motion in which the velocity of an object changes by an equal amount in every equal period of time.
Being a the constant acceleration, vo the initial speed, vf the final speed, and t the time, the following relation applies:

Solving for a:

The runner speeds up from vo=5 m/s to vf=9 m/s in t=4 seconds, thus:


The runner's acceleration was 
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Reconstruction failed by most other measures: Radical Republican legislation ultimately nuclear to protect former slaves from white persecution and failed to engender fundamental changes to the social fabric of the South. When President Rutherford B. federalism debate that had been an issue since the 1790s almost mediately . Hayes removed federal troops from the South in 1877, former Confederate officials and slave returned to nuclear the support of a conservative Supreme Court, these newly empowered white southern politicians passed black codes, voter qualifications, and other anti-progressive legislation to reverse the rights that blacks had gained during Radical Reconstruction. The U.S. Supreme Court bolstered this federalism anti-progressive movement federalism with decisions in the Slaughterhouse Cases, the Civil Rights Cases, and United States v.
Learn more about Reconstruction on:
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Answer:
Engular velocity: 
Linear velocity: 
The time it takes:

Explanation:
The magnitude of the centripetal acceleration can be related to the angular velocity and radius as:
(1)
Solving for w:
(2)
Replacing a=9,8m/s2 and r=6,375,000m:
(3)
And the angular velocity relates to the linear velocity:

The perimeter of the orbit is:

The time it takes:

Answer:
1/2
Explanation:
The energy stored in a capacitor is given by

where
C is the capacitance
V is the potential difference
Calling
the capacitance of capacitor 1 and
its potential difference, the energy stored in capacitor 1 is

For capacitor 2, we have:
- The capacitance is half that of capacitor 1: 
- The voltage is twice the voltage of capacitor 1: 
so the energy stored in capacitor 2 is

So the ratio between the two energies is
