The spiral structure of the milky way can be explained by long lived quasi-static density waves<em>, </em><em>according to the lin-shu hypothesis. </em>Curiously, the waves of higher density gas and stars (seen as spiral arms) appear to remain static as stars move around the galaxy. This explained by assuming that the gravitational disturbances cause by the 'clumping' material in the arms does not affect the gravitational field of the galaxy as whole and is therefore negligible.
source: Astrophysicist
Answer:
Negative acceleration occurs when the acceleration vector points to the left.
1. Object slowing down in the positive direction.
2. Object speeding up in the negative direction.
Following six statements:
1. T
2. F
3. T
4. T
5. F
6. T
Check direction of acceleration vector.
Answer:
Lorsque l'on détend l'air son volume augmente et sa pression diminue. L'air qui est un mélange de gaz est compressible et expansible. – Lorsque l'on comprime l'air, son volume diminue et sa pression augmente. – Lorsque l'on détend l'air, son volume augmente et sa pression diminue.
A gravitational force between objects depends on two things- their masses and the distance between them. So the greater the mass and the less distance there is, the more gravitational force and is the mass is less and the distance is great the gravitational force is weak
