Why there is no force acting in an object with constant velocity?

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Discussion Overview

The discussion revolves around the concept of forces acting on an object moving with constant velocity, particularly in the context of riding a bicycle. Participants explore the relationship between applied forces, resistance forces, and the conditions for maintaining constant velocity.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that continuous force is necessary for motion, questioning the theory that an object can move at constant velocity without an acting force.
  • Another participant explains that while forces like wind resistance and friction act on a bicycle, if no net force is present, the bicycle will continue to move at constant velocity after pedaling stops.
  • It is noted that there are forces acting on an object moving with constant velocity, but their resultant is zero, which aligns with the second postulate of mechanics that focuses on net force rather than individual forces.
  • A participant reiterates that the force exerted while pedaling only serves to counteract resistance forces, leading to a state of zero net force and thus constant velocity.
  • Another participant confirms that constant velocity implies no acceleration, which is associated with a zero sum of forces.
  • A participant expresses a need for more clarity on the topic, indicating ongoing uncertainty.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and role of forces in maintaining constant velocity. While some agree on the concept of zero net force, others remain uncertain about the implications of these forces.

Contextual Notes

The discussion highlights the complexity of understanding forces in relation to motion, with participants addressing the nuances of individual forces versus net force and the conditions for constant velocity.

abi.ayan
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According to my level of knowledge,my point of view regarding an object moving with constant velocity is that there should be a force acting on it for its continuous motion(eg:when riding bicycle we give a force continuously).But the theory says it is not.can anyone explain?
 
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On a bicycle, if you stop pedaling, you don't immediately stop. You keep moving with the same velocity you had just before you stopped pedaling, and then you gradually slow down. Slowing down is due to forces acting on your bicycle--wind resistance, friction in the wheels, etc. But if there were no force acting on your bicycle to slow you down, you would continue to coast at a constant velocity once you stop pedaling. But since there are forces acting to slow you down such as wind resistance, maintaining a constant speed requires you to pedal just enough to cancel the resistance force--when one force cancels the other, you are left with zero net force and thus remain at a constant velocity.
 
But there are forces acting on a material point moving with constant velocity. It's just that their resultant is 0. The second postulate of mechanics only speaks about the resultant force, not on individual components.
 
Jolb said:
On a bicycle, if you stop pedaling, you don't immediately stop. You keep moving with the same velocity you had just before you stopped pedaling, and then you gradually slow down. Slowing down is due to forces acting on your bicycle--wind resistance, friction in the wheels, etc. But if there were no force acting on your bicycle to slow you down, you would continue to coast at a constant velocity once you stop pedaling. But since there are forces acting to slow you down such as wind resistance, maintaining a constant speed requires you to pedal just enough to cancel the resistance force--when one force cancels the other, you are left with zero net force and thus remain at a constant velocity.

So the bicycle doesn't move due the force given by me.But the force I gave only cancel out the air resistant and frictonal force.I am I right?
 
abi.ayan said:
So the bicycle doesn't move due the force given by me.But the force I gave only cancel out the air resistant and frictonal force.I am I right?

That's correct. Velocity is not related to currently acting forces. Only acceleration is related to currently acting forces. constant velocity = no acceleration = sum of forces is zero.
 
A.T.
Obviously I need more clarity to understand that one

Dave
 

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