Universal gravitation: mass of 2 objects

In summary, the two objects have a gravitational magnitude of 1.00x10-8N when separated by 20.0cm, with a total mass of 5.00kg. To find the mass of each object, we use Newton's law of gravity and the fact that the total mass is equal to the sum of the individual masses. By setting one mass as 'm' and solving for the other, we get m1=5-m2. By substituting this into the equation, we can solve for m2 and then for m1. With this method, we can find the mass of each object even if they are not equal.
  • #1
mickellowery
69
0

Homework Statement


Two objects attract each other with a gravitational magnitude 1.00x10-8N when separated by 20.0cm. If the total mass of the two objects is 5.00kg what is the mass of each?


Homework Equations


Fg=G*m1m2/r2
G=6.673x10-11Nm2/kg2
I'm not real sure how to go about this one since they don't say whether or not the two masses are equal. The answers turn out to not be equal which killed my idea of how to set this up. I was going to try making one of the masses 5/2 and solving for the other mass but this just gives me half of the total mass.

The Attempt at a Solution

 
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  • #2
If the mass of one of the objects was 'm', what would be the mass of the other?
 
  • #3
Thats a great question Doc. Would it just be m/2? I'm not very sure.
 
  • #4
mickellowery said:
Would it just be m/2? I'm not very sure.
No guessing. Figure it out. Hint: What's the total mass?

Here's how to look at it. You've already called the masses m1 and m2. That's perfectly fine. You already have one equation: Newton's law of gravity. But since you have two unknowns, you'll need a second equation. Hint: m1 + m2 = ??
 
  • #5
Oh OK so then it would be m1=5-m2. Then I would sub in 5-m2 for m1
 
  • #6
Yep. Then you'd solve for m2 (and then for m1).
 
  • #7
Alrighty thanks much for helping a nearly lost cause in physics.
 

FAQ: Universal gravitation: mass of 2 objects

What is universal gravitation?

Universal gravitation is a physical law that describes the force of attraction between any two objects with mass in the universe. It states that the force of attraction is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

How do you calculate the force of gravity between two objects?

The force of gravity between two objects can be calculated using the equation F = G(m1m2)/r^2, where F is the force of gravity, G is the gravitational constant, m1 and m2 are the masses of the two objects, and r is the distance between them.

Is the mass of the two objects the only factor that affects the force of gravity?

No, the force of gravity is also affected by the distance between the two objects. As the distance between the objects increases, the force of gravity decreases.

How does the mass of the two objects affect the force of gravity?

The more massive the two objects are, the greater the force of gravity between them will be. This means that objects with larger masses will have a stronger gravitational pull than objects with smaller masses.

What is the significance of the mass of two objects in universal gravitation?

The mass of two objects is a crucial factor in universal gravitation as it determines the strength of the gravitational force between them. The greater the mass of the objects, the stronger their gravitational pull will be, and the more they will be attracted to each other.

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