Explaining Rigid Body Movement with 15*3*10^8m Stick

In summary, the conversation discusses the concept of pushing a stick with one end and how it takes time for the other end to move, rather than being instantaneous. The speaker asks about the speed of the force and it is explained that it travels at the speed of sound, not the speed of light. They also mention a discussion on this topic in a forum post.
  • #1
arunrajagopal
4
0
Assume a stick
of length 15*3*10^8 metre.
One end points towards
me, at the other end we
place a ball very near to
the end of the stick. If i
push the end pointing
towards me with some
force, instantaneously the
ball will be moved(~). At
the same time, a light
beam emanating
alongside me would take
15 seconds to reach that
ball. How can i change the
information of a space
even before the light beam
reaches out to that place
(~)? This question appears
to be childish, pardon my
innocence, explain me
please. I've been baffled
by this question since my
childhood. I know this
question is a flaw or
immature way of
understanding a concept,
please find out the
misconception I've been
thinking of.

P.S: I'm NOT gonna
SHAKE, or BANG, or MAKE
VIBRATE the stick. This situation is slightly analogous to Newton's gravity model which contradicts with light's speed limit later overturned by einstein's general theory of relativity, but not completely i think.

(~)-Doubtful.
 
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  • #2
arunrajagopal said:
If i
push the end pointing
towards me with some
force, instantaneously the
ball will be moved(~).
When you push one end of the 'rigid' body, it takes time for the other end to move. It's not instantaneous.
 
  • #3
Doc Al said:
When you push one end of the 'rigid' body, it takes time for the other end to move. It's not instantaneous.

That means the ball will move 15 seconds later after you pushed the rod? The force itself is also traveling at the speed of light?
 
  • #4
No, at the speed of sound. DaleSpam posted a nice FAQ reply to this question yesterday.

https://www.physicsforums.com/showthread.php?t=536289

If you hit the surface closest to you so hard that it's forced to move faster than the speed of sound in the material, it will probably break. It will also create a disturbance that propagates faster than the speed of sound for a little while (but obviously never faster than the object that hit it), and eventually turns into a plain old sound wave when it has lost enough energy.
 
Last edited by a moderator:

Related to Explaining Rigid Body Movement with 15*3*10^8m Stick

1. What is rigid body movement?

Rigid body movement refers to the motion of a solid object or system of objects where all points of the object(s) move in a parallel manner without any internal deformation or change in shape.

2. How is rigid body movement different from other types of motion?

Rigid body movement is different from other types of motion, such as fluid or elastic motion, because the shape and size of the object(s) remains constant throughout the motion. In other types of motion, there may be changes in shape or deformation of the object(s) due to external forces.

3. How is rigid body movement explained using a 15*3*10^8m stick?

A 15*3*10^8m stick can be used to demonstrate rigid body movement by imagining it as a solid, inflexible object. As the stick moves through space, all points on the stick maintain the same distance and orientation from each other, showing parallel motion without any changes in shape.

4. What is the significance of the 15*3*10^8m measurement in explaining rigid body movement?

The 15*3*10^8m measurement is simply an example of the size and scale of the object used to demonstrate rigid body movement. The specific measurement is not necessarily significant, but rather the concept of a solid, inflexible object moving in parallel motion.

5. Can rigid body movement occur in real-world scenarios?

Yes, rigid body movement is commonly observed in everyday life. Examples include the motion of a rolling ball, the rotation of a spinning top, and the movement of a car on a straight road. Rigid body movement is also an important concept in fields such as mechanics, engineering, and robotics.

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