
(a)
The time taken by the blob to move from A to B if the distance from point A to point B in the following figure is
(a)

Answer to Problem 16Q
Solution:
Explanation of Solution
Given data:
Distance between point A and point B is
Speed of the blob is
Blob moves toward Earth from point A through a distance
Blob moves in a side ways, transverse direction through a distance
Formula used:
The expression for the speed of any object is written as,
Here,
Explanation:
Write the expression for the speed of blob.
Rearrange this for
Substitute
Conclusion:
Therefore, the time taken by blob to move from A to B is
(b)
The year in which the light from B reaches Earth if the distance from A to point B in the following figure is
(b)

Answer to Problem 16Q
Solution:
Explanation of Solution
Introduction:
If any object appears to be moving faster than the speed of light, the motion of that object is called superluminal motion. Some astronomical objects such as quasars, blazars, radio-galaxies show superluminal motion.
Explanation:
It is given that the light from the blob at A reaches Earth in
Conclusion:
Therefore, the year in which the light from B reaches the Earth is
(c)
The apparent speed of the the blob moving across the sky as seen from the Earth if the distance from point A to point B in the following figure is
(c)

Answer to Problem 16Q
Solution:
The speed of the the blob moving across the sky appears to be 1.7 times the speed of light.
Explanation of Solution
Given data:
Distance between two points in the sky is
Time taken by light to travel from one point to another is
Formula used:
The expression for the speed of any object is written as,
Here,
Explanation:
Write the expression for the speed of blob.
Substitute
Conclusion:
Therefore, the apparent speed of the the blob is 1.7 times the speed of light.
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Chapter 24 Solutions
Universe
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