Special Relativity and spacecraft

AI Thread Summary
A spacecraft traveling at 1.8x10^8 m/s relative to Earth measures two events to be 32 hours apart. The discussion clarifies that the spacecraft's path is straight, not circular, and confirms the events are at the same location on Earth. To find the time interval at a higher speed of 2.82x10^8 m/s, the time dilation formula is applied. The final calculated time interval observed by the spacecraft at the new speed is 75 hours. The conversation emphasizes the importance of correctly interpreting the problem's wording for accurate calculations.
sean-820
Messages
25
Reaction score
0

Homework Statement



A spacecraft is traveling around Earth at 1.8x10^8m/s relative to the earth. If the spacecraft determines two events on Earth to be 32H, what time interval would they find if the spacecraft is traveling at 2.82x10^8m/s?

Homework Equations



delta Tm=delta Ts/[1-(v^2)/(c^2)]

Where Tm= time viewed by a moving object
Ts= time viewed y a stationary object
v= velocity
c= speed of light=3x10^8m/s

The Attempt at a Solution



This is the equation i know, but i don't know how to incorporate the 32h from just the spacecraft s frame of reference
 
Physics news on Phys.org
sean-820 said:

Homework Statement



A spacecraft is traveling around Earth at 1.8x10^8m/s relative to the earth. If the spacecraft determines two events on Earth to be 32H, what time interval would they find if the spacecraft is traveling at 2.82x10^8m/s?

Homework Equations



delta Tm=delta Ts/[1-(v^2)/(c^2)]

Where Tm= time viewed by a moving object
Ts= time viewed y a stationary object
v= velocity
c= speed of light=3x10^8m/s

The Attempt at a Solution



This is the equation i know, but i don't know how to incorporate the 32h from just the spacecraft s frame of reference

The spacecraft can't be traveling "around" the Earth at this speed if you mean that it is circling the earth. Does 32H mean 32 hours? Are the events at the same location on the earth? Can you give us the exact wording of the question?

AM
 
The spacecraft can't be traveling "around" the Earth at this speed if you mean that it is circling the earth.Yes its path is around Earth at that speed. Does 32H mean 32 hours? yesAre the events at the same location on the earth?yes Can you give us the exact wording of the question?

A spacecraft has a speed of 1.8x10^8m/s with respect to earth. The spacecraft determines two events on Earth to be 32 hours apart. What time interval would they find if the spacecraft is traveling at 2.82x10^8m/s (instead of 1.8x10^8)?
 
sean-820 said:
The spacecraft can't be traveling "around" the Earth at this speed if you mean that it is circling the earth.Yes its path is around Earth at that speed. Does 32H mean 32 hours? yesAre the events at the same location on the earth?yes Can you give us the exact wording of the question?

A spacecraft has a speed of 1.8x10^8m/s with respect to earth. The spacecraft determines two events on Earth to be 32 hours apart. What time interval would they find if the spacecraft is traveling at 2.82x10^8m/s (instead of 1.8x10^8)?
Ok. The question simply states that it is moving at a constant speed relative to the Earth ie. in a straight line. It has more than enough escape velocity so it cannot be going around the earth.

How do you transform time from one inertial frame to another?

AM
 
Last edited:
I solved it. The answer is 75 hours. I think it was more the wording of the question that messed me up. Escape velocity wouldn't matter as it isn't necessarily orbiting earth.To solve, i just used the formula given twice. First time to sub in the initial velocity and time to get the stationary observers time, then did the equation again using this stationary time to find time observed by the spacecraft at its new speed.

Thanks for trying to help
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
TL;DR Summary: Find Electric field due to charges between 2 parallel infinite planes using Gauss law at any point Here's the diagram. We have a uniform p (rho) density of charges between 2 infinite planes in the cartesian coordinates system. I used a cube of thickness a that spans from z=-a/2 to z=a/2 as a Gaussian surface, each side of the cube has area A. I know that the field depends only on z since there is translational invariance in x and y directions because the planes are...
Back
Top