The distance from Earth to the star Epsilon Eridani is about 10.5 light years. Which of the following statements is true?
2 answers:
Answer:
B. It takes a ray of light 10.5 years to travel from Earth to Epsilon Eridani.
Explanation:
Light year is the unit of the distance between two points. It is defined as the distance traveled by light from one point to other for given interval of time.
So here if the distance is given as 10.5 light years then it means the distance between Earth and the given star is same as that the distance traveled by the light in 10.5 years.
So here we can say that distance is
so here the correct answer will be
B. It takes a ray of light 10.5 years to travel from Earth to Epsilon Eridani.
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Answer:
Constant speed: yes
Constant velocity: no
Explanation:
Let's remind the definition of speed and velocity:
- Speed is a scalar quantity, which is equal to the ratio between the distance covered (regardless of the direction) and the time taken:
- Velocity is a vector quantity, so it has both a magnitude and a direction. The magnitude is equal to the rate between the displacement of the object and the time taken, while the direction is the same as the displacement.
In this problem, we notice that:
- The speed of the car remains constant, as it is 90 km/h
- However, its direction of motion changes while the car travels round the corner: this means that the direction of the velocity is also changing, therefore velocity is not constant.