Artificial gravity has been portrayed in many sci-fi movies and novels by the use of giant rotating cylinder-shaped spaceships to generate acceleration. According to Einstein, acceleration is equivalent to gravity. However, I have been wondering what happens when a person jumps in a rotating spaceship. Thus, I decided to do a little thought experiment.
Assume we have a giant cylinder-shaped spaceship that rotates at a constant angular velocity w. A person standing inside the spaceship will experience centripetal acceleration directed towards the axis of rotation (or the centre of the spaceship in that particular cross-sectional frame) and the resulting normal force acting on him/her will cause a sensation of gravity. However, if the person jumps in the direction towards the centre, he/she will lift off the surface with 2 velocities components- the tangential velocity and initial velocity towards the center. The resultant velocity can be calculated and he/she will 'fly' in a straight line towards the inner surface of the spaceship at an angle as seen in the video and end up landing at a different spot from where he/she lifted off. This is because once the person is off the surface, there is no longer any resultant force acting on him/her (neglect air resistance), unlike on Earth where gravity continues to act even when you are airborne.
Assume we have a giant cylinder-shaped spaceship that rotates at a constant angular velocity w. A person standing inside the spaceship will experience centripetal acceleration directed towards the axis of rotation (or the centre of the spaceship in that particular cross-sectional frame) and the resulting normal force acting on him/her will cause a sensation of gravity. However, if the person jumps in the direction towards the centre, he/she will lift off the surface with 2 velocities components- the tangential velocity and initial velocity towards the center. The resultant velocity can be calculated and he/she will 'fly' in a straight line towards the inner surface of the spaceship at an angle as seen in the video and end up landing at a different spot from where he/she lifted off. This is because once the person is off the surface, there is no longer any resultant force acting on him/her (neglect air resistance), unlike on Earth where gravity continues to act even when you are airborne.
(PS: Does anyone know how to upload flash animation files onto blogger? I had to convert the flash file to .avi format which is much larger in file size)
Applying the same reasoning, objects 'falling' in a rotating spaceship will not 'fall' in a straight vertical line but will end up hitting the ground at some horizontal distance away from the point at which is starts 'falling'. This apparent curved motion of objects is called Coriolis effect. In this respect, artificial gravity is different from real gravity and may lead to many problems living in space.
Prolonged exposure to weightlessness can cause health problems in astronauts such as loss of bone mass, muscle atrophy, dehydration, anemia and weakened immunity, among others. Such adverse effects can be countered by rigorous exercise or by inducing gravity. Currently, a significant amount of time on exercising by astronauts while on space missions. This is not very economical as it results in less time for conducting experiments. In the future when people live in space colonies, we cannot expect everyone to spend so much time exercising. Thus it is of utmost importance to find a way to create artificial gravity that is as close to the real thing as possible. Currently, the only way to create real gravity is to use mass. In order to create 1g, we will need the mass of the Earth, so clearly that is not a viable option for space missions. So for now, we will just have to stick to the idea of large rotating spaceships and put up with large Coriolis forces.
8 comments:
when you jump in a moving bus, do you land on the same spot?
anyway, isn't the coriolis force in effect on earth as well? in meterology, some ocean flow dynamics, etc.
even for artillery shells, the coriolis effect is taken into account for long-range bombardment.
anyway, isn't the coriolis force just an extension of the idea that actions look different from different frames of reference? (in this case, inertial frame vs rotating frame)
Hi Jared, haven't heard from you for quite some time. As to ur 1st qn, if u jump in a bus moving at the same velocity, u will land on the same spot because u took off the floor with the same initial horizontal velocity. U only change the vertical velocity when u jump. However, if the bus is accelerating while u jump, then u will land at a different spot.
Yes, the coriolis force is manifest on Earth too. Things do indeed look different from different frames of reference. That's y an astronaut jumping in a rotating cylinder-shaped spacecraft will not land on the same spot.
Perhaps, I shall agree with your phrase
I have thought and have removed the message
Certainly. All above told the truth. We can communicate on this theme.
Yeah sure, I would love to discuss about this topic though I am no expert in this field.
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