Some questions regarding gravity

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SUMMARY

This discussion addresses two questions regarding the nature of gravity and motion in extreme conditions. The first question posits whether gravity ceases to function for objects approaching the speed of light. The conclusion is that gravity continues to increase an object's velocity and momentum, with momentum increasing indefinitely as velocity approaches the speed of light, due to the relativistic factor gamma (γ). The second question confirms that a bullet fired vertically upwards on the moon will land at the same speed it was fired, as the moon's environment approximates a vacuum.

PREREQUISITES
  • Understanding of Einstein's theory of relativity
  • Familiarity with the concept of momentum (p = mγv)
  • Knowledge of gravitational effects in a vacuum
  • Basic physics of projectile motion
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  • Study Einstein's theory of relativity in detail
  • Explore the implications of relativistic momentum
  • Research gravitational effects in low-gravity environments
  • Examine the physics of projectile motion in vacuum conditions
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Physicists, students of physics, and anyone interested in the principles of gravity and motion in relativistic contexts.

saln1
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2 random thoughts that struck me:

Q1. If an object is moving downwards towards a large mass at just under the speed of light, will the effects of gravity effectively "stop working" in order to keep the velocity below c?

Q2. If a bullet is fired vertically upwards on the surface of the moon, will the speed at which it lands be the exact same as the speed at which it left the gun, since it's effectively moving in a vacuum?
 
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saln1 said:
2 random thoughts that struck me:

Q1. If an object is moving downwards towards a large mass at just under the speed of light, will the effects of gravity effectively "stop working" in order to keep the velocity below c?

Q2. If a bullet is fired vertically upwards on the surface of the moon, will the speed at which it lands be the exact same as the speed at which it left the gun, since it's effectively moving in a vacuum?

Q1: Gravity will continue increasing the object's velocity and momentum. The velocity approaches c, but the momentum, which is given by p=m\gamma v keeps increasing without approaching a limit, because \gamma approaches infinity as v approaches c.

Q2: yes
 

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