Newton's 2nd law question -- pushing a block up an inclined ramp....

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Discussion Overview

The discussion revolves around applying Newton's second law to a scenario where a constant force is used to push an object up an inclined ramp at constant velocity. Participants explore the implications of constant velocity on acceleration and the net forces acting on the object.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions the application of the formula F=ma, suggesting that if a constant force is applied and the object moves at constant velocity, the acceleration should be 1 m/s².
  • Another participant points out that constant velocity implies zero acceleration, prompting confusion about the relationship between force and acceleration.
  • Some participants clarify that if the velocity is constant, the net force must be zero, which leads to discussions about the forces acting on the object, including gravity and friction.
  • There is a mention of the zero product property of multiplication, indicating confusion about how to reconcile zero acceleration with the force equation.
  • One participant emphasizes the importance of considering the net force (ΣF) rather than just the applied force in the context of Newton's second law.
  • Another participant acknowledges the need to account for all forces acting on the object, including gravitational and frictional forces, when applying F=ma to find acceleration.

Areas of Agreement / Disagreement

Participants generally agree that constant velocity indicates zero acceleration and that the net force must be zero. However, there is some confusion regarding the application of the force equation and the implications of different forces acting on the object.

Contextual Notes

Participants express uncertainty about how to correctly apply Newton's second law in this scenario, particularly regarding the definitions of forces involved and the conditions of motion on an inclined plane.

J-dizzal
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If a constant force is applied to an object and the force is pushing the object up a inclined ramp with constant velocity what is the acceleration if mass is unknown?
F=ma
F=m (1m/s^2)​
If i apply this equation then acceleration is 1m/s^2. Am i applying this formula correctly? thanks
 
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J-dizzal said:
the force is pushing the object up a inclined ramp with constant velocity

If the velocity is constant then what does that tell you about the acceleration?
 
Nugatory said:
If the velocity is constant then what does that tell you about the acceleration?
i want to say if v is constant than acceleration is zero. but when i plug that into F=ma i got F=m0 which is zero force, but that doesn't work. and this is why I am confused
 
J-dizzal said:
i want to say if v is constant than acceleration is zero. but when i plug that into F=ma i got F=m0 which is zero force, but that doesn't work. and this is why I am confused
because of the zero product property of multiplication
 
You're on the right track here - the acceleration is zero and therefore the net force is zero.

However, that zero net force is the sum of all the forces that are at play here, including gravity, friction, and the force being used to push the object up the ramp.
 
Last edited:
J-dizzal said:
i want to say if v is constant than acceleration is zero. but when i plug that into F=ma i got F=m0 which is zero force, but that doesn't work. and this is why I am confused
If you think of Newton's 2nd law as ##\Sigma F = ma## (instead of just F = ma), that will remind you that it is the net force that equals ma.
 
Newton's second law is a way of saying, if you apply a force on a mass it will accelerate, F = ma describes the way it accelerate, you can see that the force F and acceleration a have the same direction, a = F/m mean that if if you apply a force on a very massive object it wil accelerate less than it would if you apply the same force on light object, in your case the object is moving at a constant velocity, so It isn't acceleration so the net force is zero as F = m*0 suggest, it's weight is pushing downward and the constant force you apply will cancel it but pushing upwards, good luck :p
 
Doc Al said:
If you think of Newton's 2nd law as ##\Sigma F = ma## (instead of just F = ma), that will remind you that it is the net force that equals ma.
yes i forgot about the sigma there. so in the example of an object on an inclined plane there would be a contact force applied to it, but when applying F=ma i must also add in the force that is parallel to the plane from its weight and frictional forces if they apply. F=ma would be ma=Fapplied-Fgravity-Ffriction, then can solve further for acceleration.
thanks!
 

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