# The Naked Scientists Forum

### Author Topic: why do we gain mass as we travel near the speed of light  (Read 4618 times)

#### Heresjonny

• First timers
• Posts: 5
##### why do we gain mass as we travel near the speed of light
« on: 09/07/2009 21:52:28 »
I heard that when we travel near the speed of light we gain mass!

is this true and if so why does this happen??

#### Heresjonny

• First timers
• Posts: 5
##### why do we gain mass as we travel near the speed of light
« Reply #1 on: 09/07/2009 21:55:19 »
is it also true that you lose length??

#### LeeE

• Neilep Level Member
• Posts: 3382
##### why do we gain mass as we travel near the speed of light
« Reply #2 on: 10/07/2009 01:12:25 »
Yes and no to both questions; it all depends upon the frame of reference of the observer.  If the observer shares a common inertial frame of reference with the traveling object they will see no change in the object - the rest of the universe will seem to change instead.  If the observer regards themselves as being stationary with respect to the object then they will see an apparent increase in mass and a contraction in length (in the direction of travel).

Welcome to the world of relativity.

#### Heresjonny

• First timers
• Posts: 5
##### why do we gain mass as we travel near the speed of light
« Reply #3 on: 10/07/2009 08:56:14 »
Thank you
very well explained

#### lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
##### why do we gain mass as we travel near the speed of light
« Reply #4 on: 10/07/2009 19:10:47 »
I heard that when we travel near the speed of light we gain mass!

is this true and if so why does this happen??
It's false. Relativistic mass is a concept on its way to oblivion...

#### Heresjonny

• First timers
• Posts: 5
##### why do we gain mass as we travel near the speed of light
« Reply #5 on: 10/07/2009 22:04:55 »
i have started reading the new book by Prof Brain Cox and Prof Jeff Forshaw call "Why does E=mc2"

It has helped me greatly.

#### lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
##### why do we gain mass as we travel near the speed of light
« Reply #6 on: 11/07/2009 13:27:31 »
i have started reading the new book by Prof Brain Cox and Prof Jeff Forshaw call "Why does E=mc2"

It has helped me greatly.
Don't know that book. Hope it doesn't say that mass depends on velocity...

#### ScientificBoysClub

• Guest
##### why do we gain mass as we travel near the speed of light
« Reply #7 on: 14/07/2009 18:18:33 »
you need infinity amount of energy to travel at that speed . when we apply infinity amount of energy on a mass it goes for its motion kinetic energy and other remaining part  ? what happens to other part ?

yes it adds it self into mass so it becomes heavier !!
« Last Edit: 15/07/2009 10:01:26 by ScientificBoysClub »

#### lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
##### why do we gain mass as we travel near the speed of light
« Reply #8 on: 14/07/2009 18:48:59 »
you need infinity amount of energy to travel at that speed.
Ok.

Quote
when we apply infinity amount of energy on a mass half of it goes for its motion kinetic energy
No, the kinetic energy is infinite and the other part (rest energy) is finite.

Quote
yes it adds it self into mass so it becomes heavier !!
No, read the many threads on this subject on this Forum, for example:
http://www.thenakedscientists.com/forum/index.php?topic=16789.0
http://www.thenakedscientists.com/forum/index.php?topic=21363.0
« Last Edit: 15/07/2009 08:57:47 by lightarrow »

#### ScientificBoysClub

• Guest
##### why do we gain mass as we travel near the speed of light
« Reply #9 on: 15/07/2009 09:57:55 »
you need infinity amount of energy to travel at that speed.
Ok.

Quote
when we apply infinity amount of energy on a mass half of it goes for its motion kinetic energy
No, the kinetic energy is infinite and the other part (rest energy) is finite.

Quote
yes it adds it self into mass so it becomes heavier !!
No, read the many threads on this subject on this Forum, for example:
http://www.thenakedscientists.com/forum/index.php?topic=16789.0
http://www.thenakedscientists.com/forum/index.php?topic=21363.0
lol  I know it Arrow .. I just want to explain it in simple terms ...
I know K.E is infinite not half .. just wanna make it simple and object mass will become infinite

#### ScientificBoysClub

• Guest
##### why do we gain mass as we travel near the speed of light
« Reply #10 on: 15/07/2009 09:59:55 »
you need infinity amount of energy to travel at that speed.
Ok.

Quote
when we apply infinity amount of energy on a mass half of it goes for its motion kinetic energy
No, the kinetic energy is infinite and the other part (rest energy) is finite.

Quote
yes it adds it self into mass so it becomes heavier !!
No, read the many threads on this subject on this Forum, for example:
http://www.thenakedscientists.com/forum/index.php?topic=16789.0
http://www.thenakedscientists.com/forum/index.php?topic=21363.0
Energy add into mass like momentum !!?!

#### ScientificBoysClub

• Guest
##### why do we gain mass as we travel near the speed of light
« Reply #11 on: 15/07/2009 10:21:19 »
you need infinity amount of energy to travel at that speed.
Ok.

Quote
when we apply infinity amount of energy on a mass half of it goes for its motion kinetic energy
No, the kinetic energy is infinite and the other part (rest energy) is finite.

Quote
yes it adds it self into mass so it becomes heavier !!
No, read the many threads on this subject on this Forum, for example:
http://www.thenakedscientists.com/forum/index.php?topic=16789.0
http://www.thenakedscientists.com/forum/index.php?topic=21363.0
Ok it's my bad if I am wrong somewhere ...

#### syhprum

• Neilep Level Member
• Posts: 3818
• Thanked: 19 times
##### why do we gain mass as we travel near the speed of light
« Reply #12 on: 15/07/2009 15:49:33 »
Here is a simple explanation of how these effects are caused.

http://www.johnstonsarchive.net/relativity/specialrel.html.

It flows naturally from the finite speed of light.

#### The Naked Scientists Forum

##### why do we gain mass as we travel near the speed of light
« Reply #12 on: 15/07/2009 15:49:33 »