A question about speed of light

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SUMMARY

This discussion focuses on calculating the distance between two objects moving at high speeds, specifically a person walking at 5 km/h and a car traveling at 60 km/h relative to the person. The conversation also addresses the implications of two objects, X and Y, both traveling at the speed of light (186,000 miles per second), with Y having a head start of 186,000 miles. It is concluded that after one hour, both objects will remain 186,000 miles apart, as they travel at the same speed. The discussion emphasizes the importance of understanding relative velocity and the limitations of objects approaching the speed of light.

PREREQUISITES
  • Understanding of relative velocity concepts
  • Basic knowledge of speed and distance calculations
  • Familiarity with the speed of light (186,000 miles per second)
  • Ability to convert units (e.g., km/h to m/s)
NEXT STEPS
  • Study relative velocity calculations in physics
  • Learn about the implications of traveling at or near the speed of light
  • Explore the concept of time dilation in special relativity
  • Investigate the mathematical principles behind distance and speed over time
USEFUL FOR

Students of physics, educators teaching kinematics, and anyone interested in the principles of motion and the speed of light will benefit from this discussion.

nirky
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If there is a person walking along the road at the speed of 5km/h and a car traveling in the same direction as the person at 60km/h relative to the person. How to calculate their the distance between them?

Also the velocity of light is 186 000 miles per second and what if both object X and Y can travel at 186 000 miles per second but object Y has an head start of 186 000 miles. How far apart would they both be in an hour? Or will there be no difference between them?

Thanks also for your help.
 
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nirky said:
If there is a person walking along the road at the speed of 5km/h and a car traveling in the same direction as the person at 60km/h relative to the person. How to calculate their the distance between them?
Insufficient information. They could be adjacent, they could be a mile apart.

You could calculate how far apart they are after a given duration since they passed each other. Is that what you're asking?

They are separating at 55km/h. That's 55,000 metres every 3600 seconds.
Convert that to units of your choice, say metres per second, and multiply by the number of seconds of your desired duration.
nirky said:
Also the velocity of light is 186 000 miles per second
c = 186,262mi/s.

Not nitpicking - this will matter in your scenario:
nirky said:
and what if both object X and Y can travel at 186 000 miles per second but object Y has an head start of 186 000 miles. How far apart would they both be in an hour? Or will there be no difference between them?

Thanks also for your help.
They cannot travel at the speed of light (unless they're photons). But at 186,000mi/s (99.86c), they are still 262mi/s short, so it's OK.

They are traveling at the same speed. After one hour, they will be the same distance - 186,000 miles - apart. Is there a reason you would think otherwise?
 
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