[Music] The slingshot effect can be analyzed as a non-contact collision between a spacecraft and a planet or other body. Both momentum and kinetic energy are conserved, so this is an elastic collision. The slingshot effect results in a change in the velocity or the

direction, or more usually both, of the spacecraft. The planet or other body loses an amount of kinetic energy equal to that gained by the spacecraft. So, in the slingshot effect, the planet loses a certain amount of kinetic energy, which is equal to the amount of kinetic energy

gained by the spacecraft. The change in the velocity of the planet or other body is insignificant because kinetic energy equals one-half MV squared, and the mass of the planet or other body is very large compared to that of the spacecraft. An example of the use of the slingshot

effect, or gravity assist as it is otherwise known, is in the Cassini mission to Saturn. This mission made use of the slingshot effect four times, with the spacecraft gaining an energy equivalent of 75 tons of rocket fuel as a result. As can be seen from the diagram,

the trajectory of the spacecraft was in fact quite complicated. It was launched from Earth on the 6th of October 1997 and flew in towards Venus, from which it again used gravity assist on the 21st of April 1998, which is marked on the diagram as a Venus flyby.

From there, it climbed up out of the Sun's gravity well until it completed a maneuver just beyond the orbit of Earth on the 1st of December 1998. It then flew back in for a second flyby of Venus on the 20th of June 1999 and completed an Earth

A flyby on the 16th of August 1999 gained a gravity assist from Jupiter on the 30th of December 2000 and finally arrived at Saturn on the 1st of July 2004. The slingshot effect can

result in either an increase or a decrease in a spacecraft's velocity, varying in amount depending on its direction of approach and departure from the planet or other body. You can see in the diagram that if the spacecraft approaches the planet or other body from the direction opposite to the orbital

direction of the body from which it is getting a gravity boost, it will actually decelerate, and that's shown by the blue arrow. If, on the other hand, it gets a gravity assist in the direction of the orbital motion of the body, it will have an accelerated trajectory, as is shown by

the red arrow. The slingshot effect is an example of projectile motion, but the trajectories of spacecraft undergoing a gravitational assist are best modeled as hyperbolas rather than parabolas due to the change in the direction and force of gravity as the spacecraft

approaches and then moves away from the planet. The slingshot effect can be compared to throwing a tennis ball at the front of a speeding truck. Assuming that the collision is elastic, the ball is accelerated by a factor equivalent to the speed of the truck, while the effect

on the speed of the truck is negligible. So, if you throw a tennis ball at the front of a speeding truck, the tennis ball will be accelerated by a factor equivalent to the speed of the truck, but because the tennis ball weighs so much less than the truck, the truck's

Speed will be unaffected; it's the same effect as a gravity assist for a spacecraft from a planet. Summary: The slingshot effect is a non-contact, elastic collision between a spacecraft and a planet. Both momentum and kinetic energy are conserved.

The slingshot effect results in a change in the velocity and/or direction of the spacecraft. The planet or other body loses kinetic energy equal to that gained by the spacecraft. The change in the velocity of the planet is insignificant because the mass of the planet is very much larger than that of the

The Slingshot Effect - HSC Physics

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