# Gravitational force magnitude problem

• mawalker
In summary, the magnitude of the net gravitational force on the 20.0 kg mass is 3.04 * 10^-4, with forces acting in opposite directions. The direction of the net gravitational force can be found using trigonometry, with the angle being the arctan of the y-component over the x-component. The magnitude of the net gravitational force on the 5.0 kg mass is 6.6966 x 10^-7, with forces acting in perpendicular directions. The angle can be found using trigonometry as well.
mawalker

What is the magnitude of the net gravitational force on the 20.0 kg mass?
What is the direction of the net gravitational force on the 20.0 kg mass?
What is the magnitude of the net gravitational force on the 5.0 kg mass?

I'm completely lost on this.

Each pair of masses exerts equal and opposite gravitational forces on each other according to Newton's law of gravity. (Look it up if you have to.) Calculate all the forces acting on each mass and just add them up, remembering that forces are vectors.

so would the gravity be assumed to be 9.8 m/s?

mawalker said:
so would the gravity be assumed to be 9.8 m/s?

No. 9.8 m/s^2 is the acceleration due to Earth gravity near the Earth's surface. I assume in this problem you are to calculate the gravitational forces between these objects, ignoring any other gravitating bodies (such as the Earth). Pretend they are in outer space and use Newton's law of universal gravity.

i'm still not getting it. for the force on the 20 kg unit i have 6.67*10^-11*(20)*(10)/(.2)^2 + 6.67*10^-11*(20)*(5)/(.1)^2 giving me a net total force of 3.04 * 10^-4, which is incorrect

forces are vectors, not scalars

The force from the 10 kg mass points in +y direction while the force from the 5 kg mass points in the +x direction. Add them like vectors, not numbers.

i've never really understood vector addition all that much. do i just square both numbers and add them together, then take the square root?

That will work, since those vectors are perpendicular.

how do i go about finding out which direction the net gravitational force on the 20kg object is? i know it would be somewhere in between the two but i don't know how to figure out how many degrees it is.

Given the y component and x component of a vector, the angle it makes with the x-axis can be found using:
$$\tan\theta = \mbox{y-component}/\mbox{x-component}$$

What is the magnitude of the net gravitational force on the 5.0 kg mass?

I used Force in y= [G (10)(5) / r^2 ] sin theta =5.96 x 10 ^-8
r = 0.223606 sin theta = 0.2/ 0.223606 =
Force in x = [G (5)(20)/ (0.1)^2] = 6.67 x 10^-7

magnitude = sq root of (force in y) ^2 + (force in x) ^2 = 6.6966x 10^-7?

is an angle in cos or sin?

## 1. What is the "gravitational force magnitude problem"?

The gravitational force magnitude problem is a theoretical issue in physics that arises when attempting to reconcile the observed strength of the gravitational force with other fundamental forces. This problem has been a subject of debate and research for many years.

## 2. Why is the magnitude of the gravitational force considered problematic?

The magnitude of the gravitational force is considered problematic because it is significantly weaker than the other fundamental forces, such as the electromagnetic force and the strong and weak nuclear forces. This creates a discrepancy in our understanding of the fundamental forces of the universe.

## 3. What are some proposed solutions to the gravitational force magnitude problem?

Some proposed solutions include the theory of supersymmetry, which suggests that there may be additional particles that could help explain the weakness of gravity. Another proposed solution is the idea of extra dimensions, which could also help explain the difference in strength between gravity and the other forces.

## 4. How does the gravitational force magnitude problem impact our understanding of the universe?

The gravitational force magnitude problem challenges our current understanding of the fundamental forces and their interactions in the universe. It also raises questions about the nature of gravity and its role in the formation and evolution of the universe.

## 5. Are there any ongoing experiments or research related to the gravitational force magnitude problem?

Yes, there are several ongoing experiments and research projects aimed at further understanding and potentially solving the gravitational force magnitude problem. These include experiments at the Large Hadron Collider and studies of gravitational waves from sources such as black holes and neutron stars.

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