Register to reply

Inertia and Momentum.

by Mozart
Tags: inertia, momentum
Share this thread:
Mozart
#1
Apr11-06, 09:24 PM
P: 106
Are momentum and inertia kind of the same thing? I don't understand the big difference between them. The only difference I can see is that for instance my chair isn't moving but it has inertia since I would have to apply such a force to get it moving. However, I don't think I can say it has momentum right now. If a ball is rolling towards me then I feel as if I can say it has momentum and it has inertia, and in my mind I can't see the difference between them.

Please help. Thanks
Phys.Org News Partner Physics news on Phys.org
'Comb on a chip' powers new atomic clock design
Quantum leap in lasers brightens future for quantum computing
Enhanced NIST instrument enables high-speed chemical imaging of tissues
Mk
#2
Apr11-06, 11:36 PM
P: 2,056
Inertia is a property of matter, but matter at rest has what momentum?
Mozart
#3
Apr11-06, 11:51 PM
P: 106
What do you mean by at rest? Constant velocity or zero velocity.

cepheid
#4
Apr12-06, 01:40 AM
Emeritus
Sci Advisor
PF Gold
cepheid's Avatar
P: 5,197
Inertia and Momentum.

Quote Quote by Mozart
What do you mean by at rest? Constant velocity or zero velocity.
Only one of those two choices accurately describes a state of being "at rest." I'll give you two guesses which one...
G01
#5
Apr12-06, 08:23 PM
HW Helper
G01's Avatar
P: 2,688
Inertia cannot be tranferred to another body while momentum can.

If you push something and get it moving it does not loose inertia, and you do not gain any inertia.

Where as when you push something forward, the object does gain postive momentum. You will also move the opposite way and gain negative momentum. And both object gain momentum and still adhere to the conservation of momentum.
pmb_phy
#6
Apr13-06, 07:14 PM
P: 2,954
Quote Quote by Mk
Inertia is a property of matter, but matter at rest has what momentum?
Inertia is that quantity which resists the changes in momentum of an object. A particle sitting still willl still resist changes in momentum.

Pete
bobbytkc
#7
Apr15-06, 12:46 AM
P: 44
Inertia is the resistance of a massive object to changes in its acceleration. It is just a word used to say that it is difficult to make an object go faster, even though we don't really understand why.

Momentum, unlike inertia, is actually a vector quantity that gives measurement to the total amount of motion in a direction. An object twice as massive but moving in the same speed and direction has twice as much motion in that direction. An object moving twice as fast as another in the same direction, but have the same mass, has twice as much motion in that particular direction.

So in short, inertia is a property of massive objects, momentum is the measurement of a seperate property (motion) of massive objects.
lovetosinger
#8
Dec4-08, 06:48 PM
P: 4
Quote Quote by Mozart View Post
Are momentum and inertia kind of the same thing? I don't understand the big difference between them. The only difference I can see is that for instance my chair isn't moving but it has inertia since I would have to apply such a force to get it moving. However, I don't think I can say it has momentum right now. If a ball is rolling towards me then I feel as if I can say it has momentum and it has inertia, and in my mind I can't see the difference between them.

Please help. Thanks
i am still wondering the same thing because i have this weird homework paper thats hard
lovetosinger
#9
Dec4-08, 06:50 PM
P: 4
Quote Quote by G01 View Post
Inertia cannot be tranferred to another body while momentum can.

If you push something and get it moving it does not loose inertia, and you do not gain any inertia.

Where as when you push something forward, the object does gain postive momentum. You will also move the opposite way and gain negative momentum. And both object gain momentum and still adhere to the conservation of momentum.

thanks that really helps
lovetosinger
#10
Dec4-08, 07:03 PM
P: 4
thanks go1 what you said about momentum and inertia helped me!! :) !!!!
lovetosinger
#11
Dec5-08, 06:58 PM
P: 4
what school do youguys go 2
willyadventur
#12
Aug8-11, 01:14 PM
P: 17
Um Ok

But if you push a ball it initially has some inertia to over come to get it moving, but once it is rolling, because it is now spinning around, doesn’t gain inertia (which it must give up/transfer to something when it comes to a rest)? Or am I way off here?

The three types of inertia are

(1) The general concept of inertia, according to newton's first laws, concerning objects' masses when it comes to resistance.
(2) Rotational inertia
(3) Gyroscopic inertia

SO a ball rolling down a has gained inertia and momentum?

Willy
russ_watters
#13
Aug8-11, 05:00 PM
Mentor
P: 22,220
This thread is very old and we've had more recent discussions, but..
Quote Quote by willyadventur View Post
Um Ok

But if you push a ball it initially has some inertia to over come to get it moving, but once it is rolling, because it is now spinning around, doesn’t gain inertia (which it must give up/transfer to something when it comes to a rest)? Or am I way off here?
Objects do not gain inertia unless they gain mass.
SO a ball rolling down a has gained inertia and momentum?
No, it has only gained momentum.
HallsofIvy
#14
Aug9-11, 06:34 AM
Math
Emeritus
Sci Advisor
Thanks
PF Gold
P: 39,300
"Inertia" is mass.

"Momentum" is mass times velocity.
harrylin
#15
Aug9-11, 06:52 AM
P: 3,181
Quote Quote by Mozart View Post
Are momentum and inertia kind of the same thing? I don't understand the big difference between them. The only difference I can see is that for instance my chair isn't moving but it has inertia since I would have to apply such a force to get it moving. However, I don't think I can say it has momentum right now. If a ball is rolling towards me then I feel as if I can say it has momentum and it has inertia, and in my mind I can't see the difference between them.

Please help. Thanks
Inertia and mass are nearly the same thing (although not exactly). And as you know, momentum is mass times speed.

That's even so in relativity if you use the relativistic mass definition: then "inertia" is simply the inertial property of mass when you try to change an object's velocity - it's the resistance to that attempt.
If you use the rest mass definition of mass, then "inertia" is the inertial property of mass times the relativistic gamma factor.


I now see that it was a very old thread, here's a quick comment on the new post:
Quote Quote by willyadventur View Post
Um Ok

But if you push a ball it initially has some inertia to over come to get it moving, but once it is rolling, because it is now spinning around, doesn’t gain inertia (which it must give up/transfer to something when it comes to a rest)? Or am I way off here?
[..] according to newton's first laws [..]
SO a ball rolling down a has gained inertia and momentum?

Willy
No, in classical physics it doesn't gain inertia. But see my comments here above.

Harald
david90
#16
Aug17-11, 05:58 PM
P: 303
If an object has inertia of 10 kg*m^2, what does this physically mean? For example, if an object travels at 10 m/s, then in my head I can see that the object travels 10 m every sec. I guess I'm having problem understanding what kg*m^2 really mean.
PeterBo
#17
Aug19-11, 08:53 AM
P: 2
The higher Inertia an object has the more force you need to apply to alter it's velocity / placement in space.
Simply put.
Ryan_m_b
#18
Aug19-11, 09:01 AM
Mentor
Ryan_m_b's Avatar
P: 5,403
Yes;
Quote Quote by Wikipedia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass.
http://en.wikipedia.org/wiki/Inertia

EDIT: Peterbo I didn't realise that you had posted on an old thread when I replied. Looking back you can see that this thread is many years old. In future if you want to ask something feel free (in fact it is preferred) to start a new thread rather than resurrecting an old one.


Register to reply

Related Discussions
Inertia and Momentum Question Introductory Physics Homework 1
Inertia and momentum General Physics 9
Inertia, Momentum, Rotation Introductory Physics Homework 2
Inertia and conservation of momentum General Physics 1
Inertia and momentum General Physics 2