Questions About Space: Get Answers Here

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Discussion Overview

The discussion revolves around the differences in propulsion mechanisms between rockets and airplanes, as well as the behavior of plant roots in a microgravity environment. It addresses theoretical concepts related to physics and biology in the context of space travel.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants explain that rockets move by expelling fuel backwards, while airplanes rely on air for propulsion, highlighting Newton's third law of motion.
  • One participant notes that rockets produce significantly more thrust than airplanes, with the space shuttle functioning as a hybrid during its return to Earth.
  • There is a discussion about plant growth in microgravity, with some participants mentioning gravitropism and the role of light in directing plant growth in space.
  • Another participant challenges the notion that gravity does not exist in space, asserting that gravity is present, albeit in a different form than on Earth.
  • Some participants express that the terminology used regarding gravity and weight in space can lead to misunderstandings, suggesting that the term "weightlessness" may be more appropriate.
  • There is mention of the confusing behavior of plant roots in a zero-gravity environment, indicating that they do not respond to gravitational cues as they would on Earth.

Areas of Agreement / Disagreement

Participants express differing views on the existence and role of gravity in space, with some asserting that gravity is present while others suggest it is absent. The discussion on plant behavior also shows a lack of consensus regarding the terminology and understanding of gravitropism in microgravity.

Contextual Notes

There are unresolved questions regarding the definitions of gravity and weight in space, as well as the implications of these concepts on plant growth. The discussion reflects varying interpretations of scientific principles without reaching a definitive conclusion.

Misr
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Hello ,

1-Why does space rocket can move through space while airplane cannot?

2-Why does plant roots grow upwards inside a spaceship?
 
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Airplanes and Rockets both move due to Newton's third law of action and reaction. An airplane normally works by "pushing" on the air we have in our atmosphere to propel itself. There is no air in the vacuum of space. A rocket however moves forward by propelling fuel in the backwards direction thereby giving itself a forwards momentum.

As for the plants, plants are known to exhibit a phenomenon called gravitropism where polar auxin transport dictate the direction of growth. Without gravity in space, the direction of growth is dictated primarily by light.
 
1. Rocket is propelled by rocket engine which delivers a lot more thrust than an airplane engine. The space shuttle is a bit of a hybrid in that its return trip is partly like an airplane.

2. Inside a spaceship there is no up or down once it is in orbit.
 
Without gravity in space
Gravity does exist in space.
Thanks very much
 
Misr said:
Gravity does exist in space.
Thanks very much
Not very helpful, and no need to be snarky.


Yuqing said:
As for the plants, plants are known to exhibit a phenomenon called gravitropism where polar auxin transport dictate the direction of growth. Without gravity in space, the direction of growth is dictated primarily by light.
To avoid the snarky replies, the latter sentence would be better expressed as "Without weight in space ..." ... And that is still going to get snarky replies. So be it. In anticipation of such replies, google the term weightlessness.

Yuqing's response is essentially correct. Plants in space grow toward light (the above ground part, that is). We physicists need to be somewhat forgiving regarding biologists technically incorrect use of the term gravity. Nothing can sense gravity. Nonetheless, to a biologist that is exactly what plants seem to do.

The part of a plant that is above the ground grows toward light in space. The part that is below the ground, the roots, are (anthropomorphizing) utterly confused due to the lack of clues. Plant roots exhibit very funky behavior in plants grown in a zero-g environment.
 

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