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1. So if a lift is in constant acceleration upwards containing a mass m. Would the lift feel the reaction force acting on the mass m or will it feel the weight of mass m?
So if a lift is in constant acceleration upwards containing a mass m. Would the lift feel the reaction force acting on the mass m or will it feel the weight of mass m?
Lifts don't have feelings. The weight of the mass (mg) will be exerted downwards and the lift base will exert a reaction force equal in magnitude to oppose it.
3. (Original post by Kvothe the Arcane)
Lifts don't have feelings.
4. (Original post by Kvothe the Arcane)
Lifts don't have feelings. The weight of the mass (mg) will be exerted downwards and the lift base will exert a reaction force equal in magnitude to oppose it.
No what if the lift was accelerating?
So if a lift is in constant acceleration upwards containing a mass m. Would the lift feel the reaction force acting on the mass m or will it feel the weight of mass m?
The lift would "feel" the force exerted on it by the mass, which won't be the same as the weight of the mass if the lift is accelerating.

And the lift will exert a force on the mass equal and opposite to the force that the mass exerts on the lift.
6. (Original post by notnek)
7. (Original post by notnek)
The lift would "feel" the force exerted on it by the mass, which won't be the same as the weight of the mass if the lift is accelerating.
So it would 'feel' the reaction force?
8. (Original post by Sayfi)
One ugly ass lift.
So it would 'feel' the reaction force?
Which reaction? The reaction of what on what?
10. (Original post by Kvothe the Arcane)
Lifts don't have feelings.
I disagree. I find lifts to be extremely moody creatures, up and down all the time.
11. (Original post by notnek)
Which reaction? The reaction of what on what?
The reaction force the lift exerts on the mass while accelerating. This reaction force would equal the force felt on the lift by the mass?
12. (Original post by Mr M)
I disagree. I find lifts to be extremely moody creatures, up and down all the time.
The reaction force the lift exerts on the mass while accelerating. This reaction force would equal the force felt on the lift by the mass?
That's correct.

But you can't really say that the lift feels the reaction that it applies to the mass (because it's the lift that is applying this reaction).

The reaction from the lift on the mass is equal in magnitude and opposite in direction to the force exerted on the lift by the mass.
14. (Original post by notnek)
That's correct.

But you can't really say that the lift feels the reaction that it applies to the mass (because it's the lift that is applying this reaction).

The reaction from the lift on the mass is equal in magnitude and opposite in direction to the force exerted on the lift by the mass.
Newton's third law states that every action has an equal and opposite reaction. This means that if the lift exerts a force on the mass, the the mass exerts an equal and opposite force on the mass in the opposite direction. So it's not necessarily wrong in stating that the lift 'feels' the reaction force it exerts on the mass.
15. Think about the lift and the mass separately. This lift experiences: it's own weight, the tension in the lift cable, the reaction force of the mass on the lift.

The mas experiences: it's own weight and the reaction of the lift on the mass.

The resultant acceleration for both objects is the same.
16. (Original post by Darth_Narwhale)
Think about the lift and the mass separately. This lift experiences: it's own weight, the tension in the lift cable, the reaction force of the mass on the lift.

The mas experiences: it's own weight and the reaction of the lift on the mass.

The resultant acceleration for both objects is the same.
Yep. Thanks. I just wanted to clarify that.
Yep. Thanks. I just wanted to clarify that.
I think we were both in agreement the whole time. It just wasn't clear when you said the 'reaction' if you meant the reaction of the lift on the mass or the reaction of the mass on the lift.
So if a lift is in constant acceleration upwards containing a mass m. Would the lift feel the reaction force acting on the mass m or will it feel the weight of mass m?
nope

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