Need a definition/explanation of "mass".

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H

HappyPuppy

Lifer
Apr 5, 2001
16,997
2
71
As in physics. Kid next door came over and asked me to explain "mass" to her. It's been too many moons since I studied chemistry or physics and I couldn't come up with an explanation.

Can one of you college geeks give me a simple explanation?

No pics, but if I get a good answer I'll post one. She's 20, blonde and loves to party!

Edit: I'll be back after while. It's time to whip up some grub.
 
M

MrBond

Diamond Member
Feb 5, 2000
9,911
0
76
The amount of matter contained in an object

Matter - anything that has mass and takes up space

OK, so it's kind of a circular defination, but it should work
 
N8Magic

N8Magic

Lifer
Dec 12, 2000
11,624
1
81
No pics, but if I get a good answer I'll post one. She's 20, blonde and loves to party!
Click to expand...
Now you're speaking my language! :p

Mass (symbolized m) is a dimensionless quantity representing the amount of matter in a particle or object. The standard unit of mass in the International System (SI) is the kilogram (kg).

Mass is measured by determining the extent to which a particle or object resists a change in its direction or speed when a force is applied.


 
V

Viper GTS

Lifer
Oct 13, 1999
38,107
433
136
Mass = How much matter
Weight = How much attraction exists between two groups of matter

Viper GTS
 
A

Ameesh

Lifer
Apr 3, 2001
23,686
1
0
Originally posted by: Colt45
for the most part, mass = weight.

'cept weight is supposedly wrong, and most thing you use weight for should be mass.
Click to expand...

dont post if you dont know what your are talkin about, weight is mass * acceleration, on earth it would be a = g = ~9.8




 
A

Ameesh

Lifer
Apr 3, 2001
23,686
1
0
Originally posted by: J0hnny
F=ma so therefore mass= Force/Acceleration

Now where is the pic!!
Click to expand...

hahaha try explaining force over acceleration to someone who cant explain what mass is. lol!
 
R

Rahminator

Senior member
Oct 11, 2001
726
0
0
Mass is the measurement of inertia, which is the tendency of an object to resist any attempt to change its motion.
 
M

Moonbeam

Elite Member
Nov 24, 1999
74,815
6,778
126
Ya got a railroad car on a level frictionless track slowly rolling along. You go up in front of it and push against it to stop it. You push with a pretty constant force. It takes ya a hundred yards of backpedaling and pushing to stop the car. You do exactly the same thing with another car, but this time it takes twice as long, two hundred yards to stop. The second car was twice as massive as the first. M= the car. F= how hard you push to slow it down. The distance to stop is a function of the rate of acceleration or in this case negative acceleration or deceleration. m=f/a If you halve a you double m, or a mass that takes twice as long to decelerate or accelerate is twice as massive.

Weight is very similar but instead of a train rolling down a frictionless track you have a string resisting the force of gravity. The earth is trying to accelerate a body on a scale toward the center of the earth. In this case the force f exerted by a spring resists or prevents the object m from acceleration a toward the center of earth. A mass twice as massive depresses the spring to the point where it applies twice the resistance to falling. Weight is just an arbitrary unite standard of mass selected by convention and stuck in a vault somewhere. Weight is a comparison against that standard, how many standard weighed masses the object contains. Here (a)cceleration is gravity and doesn't change. In this case it takes twice the spring force to support twice the weight. m=f/a Divide the same value into twice as big a number and you get twice as big a value.
 
Hayabusa Rider

Hayabusa Rider

Admin Emeritus & Elite Member
Jan 26, 2000
50,879
4,268
126
Definitions are kinda lame arent they. Best is that mass is the amount of matter present, but that is as I said lame.

Particles with charge have a field and and associated mediating particle- the electromagnetic field and the photon

Particles with mass have/had a postulated field and particle too. The Higgs field and particle. Unfortunately the Higgs particle has not been seen in accelerators that should have produced it, so either it does not exist at all, or it is so massive, that our concept of it is wildly wrong.

Back to the drawing board ;)
 
P

piku

Diamond Member
May 30, 2000
4,049
1
0
Make sure to study with her when she starts learning about kinetic energy...
 
M

Moonbeam

Elite Member
Nov 24, 1999
74,815
6,778
126
Just whip it out and say;

"Now, this is mass"
------------------------------------

It might be mass, but it wouldn't be class.
 
N

Noriaki

Lifer
Jun 3, 2000
13,640
1
71
Mass and Weight are not equal, ever at anything...they are not the same unit, and they don't measure the same thing. They are related, but distinct.

Weight is a force, and is measured in Newtons. Weight is not mesaured in Kilograms (or Pounds). Despite the common statement like "I weight 127Kg", giving a weight in kilograms is nonsense.

My mass is 127kg (280lbs)...I weigh about 1250 Newtons.

Weight = m * 9.8N/Kg (m is mass in Kg)

Of course everyone (including myself) will continue to state their mass as a weight.

Anyways...I won't try to give another definatition of mass. The one I'd use has already been posted.
 
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