The person scale is accelerated toward Earth. Reply: It is true that the reading of the scale is zero, but that does not imply that gravity is absent. Does that imply that there is no gravity inside the ISS? Query: If a person stands on a scale inside the ISS, it will give a reading of zero. The ISS is in the gravitational field of the Earth which has the strengthĪ gravity = G M Earth r 2 \mathbf = 0, a = a gravity − a centripetal = 0, so that astronauts experience a state of weightlessness. However, from the perspective of the person in the elevator, the phone stays at the same height, appearing to float. In the frame of the Earth, the person and the phone fall freely under gravity. Suppose a person is standing in an elevator in freefall, when they hold out their phone and release it. The same phenomenon is seen in a freely falling elevator. But counter to what we might expect, this is due precisely to the pull of gravity, not its absence!
#Google but no gravity free
In fact, when orbiting the Earth, the ISS (or any other satellite) experiences a perfect balance between the inward pull of gravity, and the centripetal acceleration it requires to keep moving in a circle.Īs such, objects inside in ISS experience a constant free fall toward Earth, giving the sensation and appearance of weightlessness. So where does the force come from? It comes from the gravitational pull of the Earth. Here we have the same need but the walls of the ISS can't provide such a force, after all the ISS is hurtling through space and can't push off something rigid like the road. For a simple analogy, think of the force you feel from a car door when rounding a curve.
Traveling in such a circular orbit requires a force toward the center. The ISS isn't simply floating in space, at rest with respect to Earth-it is orbiting the planet at more than 17,500 mph, or 4.5 miles per second. This is analogous to the circumstance we find in the space station. It is clear that although gravity continues to act, objects in the cart experience a state of weightlessness due to their trajectory. In fact, we could release something from our hands and it would appear to float in midair, neither moving upward or downward from our perspective. Objects in the cart do not experience this force, and thus are left in free-fall until they collide with the safety belt/harness. The shape of the track imposes a trajectory on the cart, and accelerates it downward. The reason this happens is that when the track curves around (from uphill to downhill), the coaster cart (and everything in it) still has its original upward velocity. If we sit in a car on Earth's surface, it is clear that gravity is acting.ĭespite this, we know the familiar feeling of weightlessness when sitting in a car or a roller coaster that goes quickly over the crest of a hill.
To see how both things can be true, let's bring the question back down to Earth. In fact, the force of gravity does act on objects in the ISS although they appear to float freely, as they would in deep space in the complete absence of gravity.
0 kommentar(er)
