Classical mechanics and specific relativity

In summary: Since the speed of light is the same in all inertial frames, it would not make a significant difference. In summary, the conversation revolved around calculating the time it takes for neutrons from the sun to reach the earth, and whether a solution based on classical mechanics would differ from one based on special relativity. It was determined that for slow speeds, classical mechanics works fine, but for speeds close to that of light, special relativity is necessary. It was also discussed that the speed of light is the same in all inertial frames, so it would not make a significant difference in the calculations. Finally, the conversation touched on the behavior of neutrons as they reach the earth and slow down to thermal equilibrium.
  • #1
nuclear
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i was asked to calculate the time that the neutrons from the sun reach the earth. i had no problem with that but my problem comes from the 2nd part.

i was asked "would you expect a solution based on classical mechanices to differ significantly from one based on special relativity and why?"

what i thought is: there's no difference since the speed of light is the same in the inertial frame since light travel through the vacuum to reach the Earth without being affects by gravity.

is that thought valid? i dun have much knowledge in relativity.

also, i was asked to predict what will happen to the neutrons that reach the Earth with their full initial energy and then slow down to thermal equilibrium with atoms in the atmosphere.

my answer: neutrons slow down due to the decrease in temperature and decay since its halflife is just 10.25 minutes and it took 8.3 minutes to reach the earth.

again, is that reasonable?

thanks for your help. appreciate that
 
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  • #2
Originally posted by nuclear
i was asked to calculate the time that the neutrons from the sun reach the earth. i had no problem with that but my problem comes from the 2nd part.

i was asked "would you expect a solution based on classical mechanices to differ significantly from one based on special relativity and why?"
Generally, if the speed of the particle is a significant fraction of the speed of light then special relativity is needed for an accurate answer. For slow (compared to light) speeds, classical mechanics works just fine. How fast were the neutrons going compared to the speed of light?
 
  • #3
no, the speed of the neutron is not given and i assumed the neutron travel at the speed of light to earth. is it reasonable?

so i guess the answer won't differ too signigicantly since the law of physics works under different frame and just the classical mechanics is not that good dealing with light speed? is that valid?

thanks for your help.
 
  • #4
Originally posted by nuclear
no, the speed of the neutron is not given and i assumed the neutron travel at the speed of light to earth. is it reasonable?
No.
so i guess the answer won't differ too signigicantly since the law of physics works under different frame and just the classical mechanics is not that good dealing with light speed? is that valid?
I don't understand your statement. As I said earlier, the closer the speed is to that of light, the more you need to apply special relativity to get accurate results.
 

FAQ: Classical mechanics and specific relativity

What is the difference between classical mechanics and specific relativity?

Classical mechanics is a branch of physics that studies the motion of macroscopic objects, while specific relativity is a theory that describes the motion of objects at high speeds or in strong gravitational fields. Classical mechanics is based on Newton's laws of motion, while specific relativity is based on Einstein's theory of special relativity.

How does special relativity challenge our understanding of classical mechanics?

Special relativity introduced the concept of time dilation and length contraction, which contradicted the idea of absolute time and space in classical mechanics. It also showed that the laws of physics are the same for all observers in uniform motion, regardless of their relative velocities.

Can classical mechanics and specific relativity be applied to the same scenarios?

Yes, classical mechanics and specific relativity can be applied to the same scenarios, but they give different predictions. Classical mechanics is accurate for objects moving at low speeds, while specific relativity is necessary for objects moving at speeds close to the speed of light.

What is the role of energy in classical mechanics and specific relativity?

In classical mechanics, energy is conserved and is the sum of an object's kinetic and potential energy. In specific relativity, energy is still conserved, but it also includes the concept of mass-energy equivalence, where mass can be converted into energy and vice versa.

How does the theory of general relativity relate to classical mechanics and specific relativity?

The theory of general relativity is a more comprehensive theory that combines classical mechanics and specific relativity. It explains the effects of gravity on the motion of objects and also includes the concept of spacetime curvature. In scenarios with strong gravitational fields, general relativity is necessary for accurate predictions.

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