Answer:
Explanation:
A light year is a unit of length and is defined as "the distance a photon would travel in vacuum during a Julian year at the speed of light at an infinite distance from any gravitational field or magnetic field. "
In other words: It is the distance that the light travels in a year.
This unit is equivalent to , which mathematically is expressed as:
Doing the conversion:
This is the distance from Earth to Sirius in miles.
Both require time, but velocity requires displacement and speed requires distance.
Explanation:
Speed and velocity are two different quantities. In fact:
- Speed is a scalar quantity, which gives a measure of how fast an object is moving, regardless of its direction. Therefore, it only has a magnitude, which is given by the ratio between distance covered and time taken:
Therefore, speed does not take into account the direction of motion.
- Velocity, on the other hand, is a vector quantity, so it has magnitude and a direction.
The magnitude of the velocity is given by
where displacement is a vector connecting the initial point with the final point of motion of an object.
The direction of the velocity corresponds to the direction of the displacement.
It must be noted also that in certain situations, the average velocity is zero, while the speed is not zero: for example, for an object completing a circle in a certain time interval, its speed is not zero, while its velocity is zero (because the object returns to the starting point, so the displacement is zero.
Therefore, the correct answer is
Both require time, but velocity requires displacement and speed requires distance.
Learn more about speed and velocity:
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