# Weight concept

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?

phinds
Gold Member
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.

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).

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

Dale
Mentor
2020 Award
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.

Drakkith
Staff Emeritus
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.

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!!

A.T.