Why are light-years more convenient than miles, kilometers, or astronomical units (AU) for measuring the distances to stars and
1 answer:
Answer:
Stars and galaxies are very far from the Earth. If their distance were denoted by km or AU then the numbers would be very large. Light-year makes the representation of distance to be concise.
Explanation:
Stars and galaxies are very far from the Earth. If their distance were denoted by km or AU then the numbers would be very large. Light-year makes the representation of distance to be concise.
The distance light travels in one year is called a light-year.
As it can be seen here that 1 light year = 9.46728×10¹⁵ m expressing distances of stars and galaxies which are more than 1 light-year becomes easier. Converting it to km will make it 9.46728×10¹² km does not make much difference.
1 Astronomical unit (almost the distance between the Earth and Sun) = 149597870700 m is also not enough to represent the distances of stars and galaxies.
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Answer:
The total kinetic energy is 2.8m J. (NOTE: m is mass of the sphere)
Explanation:
The total kinetic energy of a sphere is given by the sum of the rotational kinetic energy and the translational kinetic energy. That is,
The rotational kinetic energy is given by
Where is the moment of inertia
and is the angular velocity
The translational kinetic energy is given by
Where is the mass
and is the translational speed (velocity)
∴
But, the moment of inertia of a sphere is given by
Where is mass
and is radius
∴
Also,
∴
Then,
∴
From the question,
Then,
Hence, the total kinetic energy is 2.8m J. (NOTE: m is mass of the sphere)