Why Is a Moving Meter Stick Measured at 80 cm Assumed to Be 100 cm at Rest?

  • Thread starter Thread starter cmantzioros
  • Start date Start date
  • Tags Tags
    Length Relative
AI Thread Summary
A moving meter stick measured at 80 cm is assumed to be 100 cm at rest because 1 meter equals 100 cm, which is its proper length in its rest frame. The formula L = Lo/gamma is used to relate the observed length (L) to the proper length (Lo) while accounting for relativistic effects. The term "gamma" represents the Lorentz factor, which depends on the speed of the object relative to the speed of light (c). The confusion arises from understanding that the 100 cm is the meter stick's length when it is not in motion. This explanation clarifies the relationship between the moving and rest lengths of the meter stick.
cmantzioros
Messages
29
Reaction score
0
I'm attempting a question that reads: A moving meter stick is measured to be 80 cm. What is its speed?

The related formula is L = Lo/gamma where gamma = 1 / (1 - (v/c)^2)^(1/2)

I looked at the solution provided and the first statement is: Lo = 100cm. I understand the rest from there but I have no idea where this 100cm comes from. Can anyone explain?
 
Physics news on Phys.org
cmantzioros said:
I looked at the solution provided and the first statement is: Lo = 100cm. I understand the rest from there but I have no idea where this 100cm comes from. Can anyone explain?
They said it was a "meter stick", and 1 meter = 100 cm. This must be its length in its own rest frame.
 
Thread 'Variable mass system : water sprayed into a moving container'

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}...
View full post »

Thread 'Egg Drop Challenge! Need ideas for winning designs'

I was thinking using 2 purple mattress samples, and taping them together, I do want other ideas though, the main guidelines are; Must have a volume LESS than 1600 cubic centimeters, and CAN'T exceed 25 cm in ANY direction. Must be LESS than 1 kg. NO parachutes. NO glue or Tape can touch the egg. MUST be able to take egg out in less than 1 minute. Grade A large eggs will be used.
View full post »

Similar threads

Ruler measurements and knowing how many decimal places to include
Replies
9
Views
2K
Length Contraction: Sally & Sheldon's Meter Stick
Replies
11
Views
2K
Angled Length Contraction (Relativity)
Replies
7
Views
3K
Special relativity - measure of a rod and simultaneity
Replies
2
Views
1K
Relativistic motion and length contraction
Replies
44
Views
2K
Confused by Lorentz transformation equation
Replies
36
Views
3K
What happens to a ball placed on a moving conveyor belt?
Replies
8
Views
3K
Angled falling Meter Stick on a frictionless surface
Replies
14
Views
2K
Question on special relativity from "Basic Relativity"
2
Replies
67
Views
4K
How does relativity affect the detection of atmospheric muons?
Replies
11
Views
2K

Hot Threads

Recent Insights

Back
Top