Can an object dropped from a moving plane achieve purely vertical motion?

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Discussion Overview

The discussion revolves around whether an object dropped from a plane moving at a constant velocity can achieve purely vertical motion, specifically under the condition of ignoring air resistance. Participants explore the implications of projectile motion and the effects of horizontal velocity on the trajectory of the object.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that without air resistance, the horizontal velocity of the object remains constant, meaning it cannot achieve purely vertical motion.
  • Questions arise regarding the direction of the object's motion and whether it can ever fall at a 90-degree angle to the Earth.
  • One participant suggests that the trajectory of the object is a projectile motion path, which does not allow for a vertical fall due to the persistent horizontal velocity.
  • Another participant emphasizes that the vertical speed increases while the horizontal speed remains fixed, leading to a decreasing vertical angle but never reaching zero.
  • There is a suggestion that if an observer were to fall alongside the object, they might perceive it as falling vertically.
  • Participants express a desire for clarification on why the vertical angle never reaches zero, linking it to the principles of Newton's first Law.

Areas of Agreement / Disagreement

Participants generally disagree on whether the object can achieve purely vertical motion, with multiple competing views presented regarding the nature of its trajectory and the effects of horizontal velocity.

Contextual Notes

The discussion does not resolve the underlying assumptions about the nature of motion in the absence of air resistance, nor does it clarify the mathematical details of projectile motion that may influence the conclusions drawn.

Gaboon
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Hi all,
I have a very simple question. Will an object dropped from a plane moving at a constant velocity ever achieve purely vertical motion? (Make sure we're not taking air resistance into account)
Thanks
 
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Gaboon said:
Hi all,
I have a very simple question. Will an object dropped from a plane moving at a constant velocity ever achieve purely vertical motion? (Make sure we're not taking air resistance into account)
Thanks
No. If there is no air resistance, the horizontal velocity of the object stays fixed at the velocity of the plane.
 
How about direction?
 
Gaboon said:
How about direction?
I don't understand the question. The object follows a projectile trajectory. Are you familiar with the equations of projectile motion with constant acceleration (gravity) and with the simplifying assumption of no air resistance?
 
Yes. Does that trajectory ever lead to object falling at 90 degrees to earth?
 
Gaboon said:
Yes. Does that trajectory ever lead to object falling at 90 degrees to earth?
No, it can't. The horizontal velocity never decreases, so the object will never fall vertically. The vertical speed keeps increasing when there is no air resistance, so the vertical angle gets smaller and smaller, but it never goes to zero.
 
Gaboon said:
Yes. Does that trajectory ever lead to object falling at 90 degrees to earth?

Only if you fall along with the object.

Zz.
 
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Ok thanks for feedback. Though I would love to know why the vertical angle never reaches zero.
 
Gaboon said:
Ok thanks for feedback. Though I would love to know why the vertical angle never reaches zero.

Read Berkeman's reply in Post #2! I have a feeling that the significance of that explanation escapes you somehow.

Zz.
 
  • #10
Gaboon said:
Ok thanks for feedback. Though I would love to know why the vertical angle never reaches zero.
You'll recognize that if there is always horizontal motion, the angle can't be zero, right? Or are you unclear about why the horizontal speed is fixed? That's due to Newton's first Law.
 

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