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How fast would a 6.0 m-long sports car have to be going past you in order for it to appear only 5.5 m long?

(a) 0.198c
(b) 0.200c
(c) 0.202c
(d) 0.204c

User Zalavari
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1 Answer

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Final answer:

To make a 6.0 m-long sports car appear only 5.5 m long, it must travel at a velocity of 0.200 times the speed of light, which is option (b) 0.200c.

Step-by-step explanation:

The question is about the phenomenon known as length contraction in special relativity. To find out how fast a 6.0 m-long sports car needs to travel to appear as 5.5 m long, we can use the length contraction formula:


L = L0 * √(1 - v^2/c^2)

Where:

  • L is the contracted length (5.5 m in this case).
  • L0 is the proper length (6.0 m).
  • v is the velocity of the object.
  • c is the speed of light in a vacuum (approximately 3.00 x 10^8 m/s).

We need to solve for v:

5.5 m = 6.0 m * √(1 - v^2/c^2)


By squaring both sides and then rearranging for v, we calculate that the velocity v works out to be 0.200c, which corresponds to answer option (b) 0.200c.

User Gopinath
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