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Gravity

Why does the direction of gravitational force change as a comet approaches the sun?
I thought it always acted centripetally

Reply 1

Phichi

Original post by dmmed

Why does the direction of gravitational force change as a comet approaches the sun?
I thought it always acted centripetally

Could you give a slightly bigger description of the situation? If a comet approaches a large body (i.e sun), initially it'll be travelling in a relatively straight line (N1). Due to N2, the unbalanced force of gravity from the body will cause acceleration in the comet, towards the body, known as centripetal acceleration. This will cause the comet to take a curved path around said body, and if close enough, orbit.

Reply 2

Callum Scott

As an object would move around a larger one [for example a sun], the direction of acceleration for the object would always be acting towards the centre of mass of the sun. As the object would move away from its previous position in space, the centre of mass of the sun would be in a slightly different direction - resulting in the direction of acceleration to also alter.
Yes, the direction of acceleration would always be acting centripetally, which is precisely why it changes!