Re: accelerating bullet

Date view Thread view Subject view Author view Attachment view

From: pauld@exploratorium.edu
Date: Sat Nov 29 2003 - 10:51:44 PST 

Message-ID: <1930.209.239.173.234.1070131904.squirrel@www.exo.net>
Date: Sat, 29 Nov 2003 10:51:44 -0800 (PST)
Subject: Re: accelerating bullet
From: pauld@exploratorium.edu

Hi Steve

There are two questions here:

Will the bullet continue to accelerate? No.

In order to accelerate a bullet a net force is required.
In the barrel of the gun in space there are high pressure gasses produced
by the explosion of the chemicals in the cartridge on one side of the
bullet and the vacuum of space on the other side exerting no force on the
bullet. So the bullet accelerates down the barrel. It even could
accelerate a little bit once it leaves the barrel because there are still
expanding gasses behind the bullet and less gas in front. However once it
is well clear of the barrel there are no net forces on the bullet so that
it will travel at constant velocity.

Can an object accelerate to the spped of light? No.

When the velocity of an object increases toward the speed of light, it
becomes more difficult to accelerate the object.

That is, if a force of 1 newton exerted on an object at rest accelerates
it at 1 m/s^2 (Quiz what is the mass of the object?)

What will happen if the same force is applied to an object travelling at
99.5% the speed of light? It will only accelerate by 0.1 m/s^2. The object
behaves as if its mass were 10 times greater than at rest. The closer to
the speed of light the more massive an object appears. Thus an object with
mass when it is at rest (rest mass) can never accelerate to the speed of
light.

Paul D

> Here's one of those simple, yet profound questions that kids ask. I am not
> sure of the answer, though it may be obvious: When someone shoots a
> bullet
> from a rifle in outer space, does the bullet continue accelerating after
> it
> leaves the gun? Will it ultimately keep on accelerating until it reaches
> the
> speed of light (assuming it doesn't run into friction)? Why does it stop
> there?
>
> _________________________________________________________________
> Has one of the new viruses infected your computer? Find out with a FREE
> online computer virus scan from McAfee. Take the FreeScan now!
> http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963
>
>
> ---------------------------------------------------------------------------
>
> To unsubscribe from pinhole, send an email to requests@exploratorium.edu
> with the words 'unsubscribe pinhole' (without the quotes) in the SUBJECT
> of the email.
>
> To subscribe to the digest and only get 1 combined message a day, send an
> email to requests@exploratorium.edu with the words 'subscribe digest
> pinhole' (without the quotes) in the SUBJECT of the email.
>
> Check out what your colleagues have written on Pinhole in the Pinhole
> archives at: http://saturn.exploratorium.edu/ti/alumni/pinhole.html
> ---------------------------------------------------------------------------
>
>

Date view Thread view Subject view Author view Attachment view

This archive was generated by hypermail 2.1.3 : Mon Aug 02 2004 - 12:05:33 PDT