Answer:

Explanation:
Time can be found by dividing the distance by the speed.

The distance is 45 meters and the speed is 12.5 meters per second.


Divide. Note that the meters, or "m" will cancel each other out.


It will take the dolphin 3.6 seconds to swim a distance of 45 meters are 12.5 meters per second.
1) The mass of the continent is 
2) The kinetic energy of the continent is 274.8 J
3) The speed of the jogger must be 2.76 m/s
Explanation:
1)
The continent is a slab of side 5900 km (so the surface is 5900 x 5900, assuming it is a square) and depth 26 km, therefore its volume is:

The mass of the continent is given by

where:
is its density
is its volume
Substituting, we find the mass:

2)
To find the kinetic energy, we need to convert the speed of the continent into m/s first.
The speed is
v = 1.6 cm/year
And we have:
1.6 cm = 0.016 m

So, the speed is

Now we can find the kinetic energy of the continent, which is given by

where
is the mass
is the speed
Substituting,

3)
The jogger in this part has the same kinetic energy of the continent, so
K = 274.8 J
And its mass is
m = 72 kg
We can write his kinetic energy as

where
v is the speed of the man
And solving the equation for v, we find his speed:

Learn more about kinetic energy:
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Our year would now be 2.8 times longer, we would also be receiving only 1/4 of the energy from the sun that we currently do. This means that we’d now be out beyond the orbit of Mars and right at the edge of the asteroid belt, and things would rapidly get very cold with temperatures expected to drop by around 50 degrees Celsius on average, and that’s with our current atmospheric composition which would not be stable in the new conditions. And also, any living thing on earth would die.
First figure out how many atoms you have with Avogadro's number. Since there are 63.5 grams/mol and you have 50.6 grams, you have (50.6/63.5)6.022E23=4.7986E23 atoms. Since there are 29 protons per atom, there are also 29 electrons per atom, so you should have a total of
29*4.7986E23=1.3916E25 electrons.
Since there is a positive charge you know some of these electrons are missing. How many are missing can be found by dividing the charge you have by the charge on the electron: 1.6E-6/1.6022E-19 = 9.98627E12 electrons are missing.
Now take the ratio of what is missing to what there should be:
9.98627E12/1.3916E25 = 7.1760873E-13