Weight or Force of Gravity: Which is Applied to a Man Lifting a Mass?

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Discussion Overview

The discussion revolves around the concepts of weight and the force of gravity in the context of a man lifting a mass. Participants explore the definitions and implications of these terms, particularly in relation to the forces acting on the man's hand while lifting the mass.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants question whether the force applied by the mass to the man's hand should be termed weight or force of gravity, noting that weight acts on the mass itself.
  • Others suggest that the force the mass applies to the hand is a contact force, also referred to as a mechanical or normal force.
  • One participant argues that weight and the force of gravity are essentially the same, stating that weight represents the downward force due to Earth's pull.
  • Another participant emphasizes that while the magnitude of the force from the mass on the hand is equal to its weight when at rest, this force can change if the mass accelerates.
  • Some participants express confusion over the phrasing of the original question and suggest looking up definitions to clarify the concepts involved.

Areas of Agreement / Disagreement

There is no consensus on the terminology used to describe the force applied by the mass to the man's hand, with multiple competing views presented. Some participants agree that the force is a contact force, while others maintain that it can be considered equivalent to weight under certain conditions.

Contextual Notes

The discussion highlights the nuances in definitions and the conditions under which different forces are considered, such as the role of acceleration in determining the force applied by the mass.

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I have a question. Suppose a man is lifting a Mass. The mass of course pushes it down. Now what is the force the mass is applying to hand of man is it Weight or Force of gravity because weight acts on mass itself. Then what we call it precisely?
 
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I think I understand what you are asking but I find it to be a very confusingly phrased question. Perhaps it would work if you were to look up the definitions of the terms mass, force, weight, and gravity to help clarify what you are asking.
 
phinds said:
I think I understand what you are asking but I find it to be a very confusingly phrased question. Perhaps it would work if you were to look up the definitions of the terms mass, force, weight, and gravity to help clarify what you are asking.
To elaborate it I would use Newtons 3rd Law
Suppose you have a mass in your hand, you are lifting it and it is in equilibrium. I am clear with the support force that is being applied by the hand at the mass. What is the force the mass is applying to hand??
 
The force of gravity and weight are essentially the same. Weight is an everyday word we use in our language that represents the downward force of an object due to the Earth's pull. Weight IS the force of gravity experienced by an object. The mass that is in your hand would exert a downward gravitational force on your hand. (As far as I know, physicists don't talk in terms of weight, always in terms of gravitational force).
 
Physicist97 said:
The force of gravity and weight are essentially the same. Weight is an everyday word we use in our language that represents the downward force of an object due to the Earth's pull. Weight IS the force of gravity experienced by an object. The mass that is in your hand would exert a downward gravitational force on your hand. (As far as I know, physicists don't talk in terms of weight, always in terms of gravitational force).
But notice weight is force something is pulled BY but it is pulling in this case
 
shayan haider said:
what is the force the mass is applying to hand of man is it Weight or Force of gravity
No. The force the mass applies to the hand is a contact force. Also called a mechanical or normal force.
 
shayan haider said:
Now what is the force the mass is applying to hand of man is it Weight or Force of gravity because weight acts on mass itself. Then what we call it precisely?

The force on the hand? Well, if we list the forces acting on the hand, we should be able to find out.

1. The weight of the man's hand (mg) acting downward.
2. The force from the man's wrist acting upward.
3. The force from the mass the hand is holding up, acting downward.

Now, it would be easy to think that number 3 is also the weight of the mass. But it's not. The magnitude of the force is equal to the weight of the mass, but, crucially, if the man were to drop his hand so that his hand and the mass accelerate downward, the force of the mass on the hand would NOT be equal to the mass's weight, but a lesser amount. This force is a contact force, the normal force, like DaleSpam said.
 
Drakkith said:
The force on the hand? Well, if we list the forces acting on the hand, we should be able to find out.

1. The weight of the man's hand (mg) acting downward.
2. The force from the man's wrist acting upward.
3. The force from the mass the hand is holding up, acting downward.

Now, it would be easy to think that number 3 is also the weight of the mass. But it's not. The magnitude of the force is equal to the weight of the mass, but, crucially, if the man were to drop his hand so that his hand and the mass accelerate downward, the force of the mass on the hand would NOT be equal to the mass's weight, but a lesser amount. This force is a contact force, the normal force, like DaleSpam said.
I am sure that the thing is applying force less than its weight!
 
shayan haider said:
I am sure that the thing is applying force less than its weight!
If the mass that you hold in your hand doesn’t accelerate, the force it applies to your hand is equal to its weight. If the mass accelerates it can be more or less in magnitude, depending on the direction of acceleration.
 
  • #10
I think it is complete explanation. Thanks!
 

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