Gravitational Force Gizmo
Name ________________________ Pd ___
The Direction of Gravitational Force
Isaac Newton realized that any two objects, no matter how large or how small, exert forces upon one another.
In this activity, you will examine the direction of the gravitational forces between two objects.
1.
The Gizmotm shows two objects, A and B. Check Show force vector for object A and examine the
purple vector. This represents the force that acts on object A due to object B.
1.
Describe the direction of the force that acts on object A.
2.
Drag object A to a different location and describe the direction of the force with A at this location.
3.
Drag object B to a different location and watch the force vector for object A as you drag. What is
always true of the direction of the force on A?
2.
With Show force vector for object A selected, turn on Show force vector for object B. A green
vector appears representing the force that acts on object B.
1.
Describe the direction of the force acting on object B.
2.
Drag both A and B to different locations. What is always true about the directions of the forces
acting on objects A and B?
The Relationship Between Force and Mass
In this activity, you will explore how the masses of the two objects affect the magnitude of the forces acting
on each object.
1.
Check all of the options in the Gizmo except for Show connecting line. Note that the masses of the
objects (mA and mB) are displayed in the center pane. Set each of these values to 10. (To set the mass to a
specific number, click in the text box, type the number, and hit Enter.) Note that the actual mass is 10 • 105
kg, or 1,000,000 kg.
1.
Place object A at the -20 point on the x-axis B at the 20 point on the y-axis. Fill in the following table
by changing the masses to the values below.
Mass of A (kg)
Mass of B (kg)
X105
X105
10
10
40
20
10
40
10
20
40
20
20
40
Distance (m)
|FA| (N)
|FB| (N)
1.
In general, what happened to the force of gravity as the masses increased?
2.
Compared to the first line of the data table, which two changes had the same effect on the force of
gravity? Why is this the case?
3.
What happened in line 4 of the data table compared to line 1?
4.
What is the relationship between the mass and force, direct or inverse? EXPLAIN your answer.
The Relationship Between Force and Distance
1.
Turn off Show force vector for both objects. Then select Show distance, Show grid, and Show vector
notation for both objects. Be sure that mA and mB are both set back to 10X105 kg. The distance between the
two objects is displayed near the top of the Gizmo. Displayed below Show vector notation are the forces that
act on each object, FA and FB, and the magnitudes of those forces, |FA| and |FB|, in Newtons (N). The
magnitude of a force is always positive.
1.
Position object A at (−5, 0) and object B at (5, 0). Fill in the following data table with information from the Gizmo.
Points for object A
Points for object B
(-5,0)
(5,0)
(-10,0)
(10,0)
(-20,0)
(20,0)
Distance between A
and B (m)
|FA| (N)
|FB| (N)
1.
In general, what happened to the force of gravity as the distance between the two went up?
2.
Divide the distance from line two by the distance on line one. Write this in fraction form.
3.
Divide the force on line two by the force on line one. Write this in fraction form.
4.
Fill in the following sentence. As the distance between object A and B was ___________ the force
was cut _____________.
5.
Does the same trend hold for lines two and three? Explain your answer.
Summary: As the mass of the objects increases, then the amount of gravity between the two objects
_____________.
As the distance between the objects increases, then the amount of gravity between the two objects
_____________.