Relativity_velocity addition and doppler effect

In summary: The Attempt at a SolutionThis problem seems to involve calculating relativistic velocities and frequency shifts. Are you familiar with the equations needed for these calculations? The first question may be answerable if all the objects involved are moving in a single line, but the second question may require a different approach. It's also important to consider the direction of movement of the ship and the moon of Eridani in order to answer the questions accurately.
  • #1
kkkeleven
1
0

Homework Statement


The Enterorise NCC1701 is cruising 0.6c above the moon of Eridani when it spots a Klingon warbird sunwards.
i. It fires a proton torpedo at speed 0.75c relative to the ship at the Klingon warbird. Assuming the proton torpedo does not accelerate, at what velocity must the Klingon warbird move to evade the proton torpedo I. relative to Enterprise II. relative to the moon of Eridani.
ii. Seeing that the warbird has moved just enough to evade the proton torpedo, the Enteprise proceeds to “open hailing frequencies”. The ship’s computer scans the library and determines that Klingon warbireds communicate at frequencies of 2.00 THZ, which frequency must the Enterprise use?
iii. Just as the Enterprise is about to send the message, colonists on the moon of Eridani also wants to hail the Klingon warbird. What frequencies should they use?

Thank you very much!

Homework Equations





The Attempt at a Solution


 
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  • #2
This is a bad problem

the direction of movement of the ship vs. the moon of Eridiani isn't given so you can't answer the questions about this moon.

How can the torpedo not accelerate and stil hit the Klingon ship if it tries to evade? It seems the first question is only answerable if the warbird and the enterprise and the torpedo all move only on a single line. Then you can use the equation for relativistic velocity addition.
 
  • #3
kkkeleven said:

Homework Statement


The Enterorise NCC1701 is cruising 0.6c above the moon of Eridani when it spots a Klingon warbird sunwards.
i. It fires a proton torpedo at speed 0.75c relative to the ship at the Klingon warbird. Assuming the proton torpedo does not accelerate, at what velocity must the Klingon warbird move to evade the proton torpedo I. relative to Enterprise II. relative to the moon of Eridani.
ii. Seeing that the warbird has moved just enough to evade the proton torpedo, the Enteprise proceeds to “open hailing frequencies”. The ship’s computer scans the library and determines that Klingon warbireds communicate at frequencies of 2.00 THZ, which frequency must the Enterprise use?
iii. Just as the Enterprise is about to send the message, colonists on the moon of Eridani also wants to hail the Klingon warbird. What frequencies should they use?

Thank you very much!

Welcome to PF :smile:
We don't provide solutions to students, but we give hints to point you in the right direction.

Homework Equations

What equations, dealing with relativistic velocities, are you aware of?
Any equations dealing with how frequency shifts with velocity?
 

FAQ: Relativity_velocity addition and doppler effect

What is the theory of relativity and how does it relate to velocity addition and the Doppler effect?

The theory of relativity, proposed by Albert Einstein, states that the laws of physics are the same for all observers, regardless of their relative motion. This includes the addition of velocities and the Doppler effect, which are two phenomena that demonstrate the effects of relativity.

How does velocity addition work in the theory of relativity?

In classical physics, velocities are simply added together. However, in the theory of relativity, velocities are combined using the relativistic velocity addition formula, which takes into account the effects of time dilation and length contraction at high speeds.

Can you explain the Doppler effect in terms of relativity?

The Doppler effect is the change in frequency or wavelength of a wave as it is observed by an observer in motion. In the context of relativity, this effect is due to the relative motion of the source and the observer, and the time dilation and length contraction that occur as a result of their velocities.

How does the Doppler effect impact our understanding of the universe?

The Doppler effect is used in astronomy to determine the motion and distance of celestial objects. By analyzing the Doppler shift of light from distant galaxies, scientists can gather information about the expansion of the universe and the presence of dark matter.

Is the theory of relativity applicable only to objects moving at high speeds?

No, the theory of relativity applies to all objects and phenomena in the universe. However, the effects of relativity become more noticeable at speeds approaching the speed of light. In everyday life, these effects are not noticeable, but they become significant in the context of space travel and astronomical observations.

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