Weight and gravitational force?

In summary, the difference between weight and gravitational force is that weight is the force exerted on an object by the earth, while gravitational force is the strength of that weight.
  • #1
chemistry1
108
0
Hi, I'm wondering if anybody could explain me the difference between these two concepts with a clear definition for someone who JUST began physics. Thanks ! Particularly, concerning this equation w=Fg=mg

Also, just to be sure I'm doing it in the right way, could I say that would be good

Ex : 15N=Fg=m*9,80N/Kg

re arrange like Fg=15N=m*9,80N/Kg

Would this be acceptable to solve for mass, knowing that these equations are equivalent ?
 
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  • #2
Just make sure you have the right unit for mass. It looks like kg. in your description.
Weight is usually defined as the gravitational force on the surface of the earth.
 
  • #3
mathman said:
Just make sure you have the right unit for mass. It looks like kg. in your description.
Weight is usually defined as the gravitational force on the surface of the earth.
Well, it's kg, isn't that the right unit ? And for weight and Fg of an object, it's exactly the same thing ?

If I have X N of weight, it means the gravitational force which gives that weight to the object will have the same numerical value ?

is this a good way of viewing it ? thanks
 
  • #4
chemistry1 said:
Well, it's kg, isn't that the right unit ?
Yes, kg is the standard SI unit for mass.

And for weight and Fg of an object, it's exactly the same thing ?
No. Weight is a force; the standard SI unit for force is the Newton.

If I have X N of weight, it means the gravitational force which gives that weight to the object will have the same numerical value ?

is this a good way of viewing it ? thanks
No. Near the Earth's surface, a 1 kg mass will have a weight of W = mg ≈ (1 kg)*(9.8 N/kg) = 9.8 N.
 
  • #5
Doc Al said:
Yes, kg is the standard SI unit for mass.


No. Weight is a force; the standard SI unit for force is the Newton.


No. Near the Earth's surface, a 1 kg mass will have a weight of W = mg ≈ (1 kg)*(9.8 N/kg) = 9.8 N.

Sorry if I misleaded you, I didn't mean that weight and Fg was in Kg. xD

It's just I don't see the relationship between weight and Gravitational force of an object.

Does w=mg and Fg=mg mean the same exact thing ? Could you tell it to me ? thanks again
 
  • #6
chemistry1 said:
It's just I don't see the relationship between weight and Gravitational force of an object.
They are the same thing: the weight of an object is the gravitational force exerted on it by the earth.

Does w=mg and Fg=mg mean the same exact thing ?
Yes.
 
  • #7
Doc Al said:
They are the same thing: the weight of an object is the gravitational force exerted on it by the earth.


Yes.

Ahhhhhhhhhhhhhhhhhh... Finally, that's what I wanted to read and be confirmed. Now, that makes me happy ! Thanks you and everyone else who posted !
 

1. How is weight different from mass?

Mass is the amount of matter an object contains, while weight is a measure of the force of gravity on an object. Mass stays the same no matter where you are in the universe, but weight can change depending on the strength of the gravitational force.

2. How does gravitational force affect weight on different planets?

The weight of an object on a different planet or celestial body is directly proportional to the strength of the gravitational force on that planet. For example, an object that weighs 100 pounds on Earth would weigh about 38 pounds on Mars due to the weaker gravitational force on Mars.

3. How is weight measured?

Weight is typically measured using a scale or balance that measures the amount of force exerted on an object by gravity. The most common unit of measurement for weight is the Newton (N).

4. Does weight change as an object moves?

No, an object's weight does not change as it moves. However, its weight may appear to change if it is moving from one location to another with a different gravitational force acting on it. For example, a person's weight would appear lighter on top of a mountain than at sea level due to the weaker gravitational force at higher altitudes.

5. How does altitude affect weight?

The higher the altitude, the further an object is from the center of the Earth and the weaker the gravitational force becomes. This means that an object's weight will decrease as altitude increases. However, this decrease is very small and only becomes noticeable at extreme altitudes.

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