- #1
terryds
- 392
- 13
I know that momentum is conserved if there are no external forces.
But, can you tell me what external forces are ?
The site http://www.physicsclassroom.com/class/energy/Lesson-2/Internal-vs-External-Forces says that internal forces are force of gravity and force of spring.
But, I think that force of gravity causes acceleration that makes the momentum increases, so it is not conserved.
Dropping a ball from some height causes the ball accelerate and momentum changes.
So, what are external forces and internal forces ?
Are force of spring and gravity external forces ?
But, can you tell me what external forces are ?
The site http://www.physicsclassroom.com/class/energy/Lesson-2/Internal-vs-External-Forces says that internal forces are force of gravity and force of spring.
But, I think that force of gravity causes acceleration that makes the momentum increases, so it is not conserved.
Dropping a ball from some height causes the ball accelerate and momentum changes.
So, what are external forces and internal forces ?
Are force of spring and gravity external forces ?