Planet's centripetal acceleration = 1.186012 m/s²
On the side of the planet facing the star, this centripetal acceleration would add to the gravitational acceleration caused by the planet's mass. On the side of the planet away from the star, the centripetal acceleration would be subtracted from the gravitational acceleration.
If the planet had the same surface gravity that Earth does, a 100 kilogram mass would be 27.5% heavier on the point where the star was at zenith than it would be on the point where the star was at nadir.
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say: You cannot feel acceleration in a car once your body sitting in the car is traveling at that speed. If the car goes 100, you go 100. And that speed is a steady 100...on a flat straight road that goes on forever. If 100 becomes 0 in an instant then you feel it because the body inside the car could not brake, so your entire body weight flies forward into the windshield and you go "SPLAT"like a bug. Guts everywhere.
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Clive say: Because you are confused between speed and velocity.
Velocity includes speed and direction. The Earth is constantly changing DIRECTION away from a straight line, but it is not changing SPEED - not significantly, anyway. Your car, on the other hand, IS changing speed.
In addition, you don't feel the movement of the Earth because you are bound to it by gravity. You are not bound by gravity to your car.
And the orbit of the Earth is so large that the directional change in velocity is insignificant from moment to moment.
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Tom S say: That (centrifugal) acceleration is negligible compared to the acceleration of Earth's gravity. Earth's orbit is very large and it take a year to complete it.
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quantumclaustrophobe say: In a sense, you're correct - Earth *is* being accelerated, all the time, by the sun's gravity. But, like a high-diver that just left the platform (or, the guys on board the space station) - they're *falling*. With regards to the sun, it's accelerating both the Earth *and you*, at the same rate. So, the only *other* force you feel is that Earth's gravity... The effect of acceleration by the Earth turning, and the Earth orbiting, is so small compared to the force of gravity acting on us that we can't truly feel it.
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