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Gwyneth Paltrow's recollection of her 2016 collision with Terry Sanderson is "consistent with the laws of physics".

The 50-year-old actress is being sued for $300,000 by the retired optometrist over their collision at Utah's Deer Valley Resort, but Dr Irving Scher - who specializes in biomechanical engineering, accident reconstruction and the safety of snow sports - suggested on Tuesday that Gwyneth's version of events is more plausible.

Asked if the actress' memory is more consistent with what he knows about biomechanical engineering, he told the court in Utah: "Yes.

"Ms Paltrow's version is consistent with the laws of physics and what we know about biomechanics."

The actress' lawyer then asked: "Does a 70-year-old man need to fall on his side with his elbow between him and the ground to cause rib fractures?"

He replied: "No."

Dr Scher subsequently explained that rib fractures can be caused by "front to back compression."

Sanderson, 76, claimed on Monday that he's become a "self-imposed recluse" since his ski collision.

Asked if he's had any anger issues since the collision, Sanderson replied: "There's no question I have a much wider range of temperament than I did before - much wider."

Sanderson explained that he can't ski anymore because of the injuries he suffered in the accident.

Explaining how the incident changed his life, he said: "I can't ski anymore.

"I was told that if I did and had another crash I could wind up full-time in a nursing home - the odds of that are very high."

Paltrow has filed a countersuit against Sanderson, arguing that he previously confessed that he didn't have a clear memory of the accident.

The Hollywood star is seeking a judgment for attorney fees plus $1.