All AP Physics 1 Resources
Example Questions
Example Question #52 : Universal Gravitation
Mass of Earth:
Universal gravitation constant:
Radius of earth:
Determine the magnitude of gravitational force by the earth on a astronaut above the surface of the earth.
Finding total distance from center of Earth to astronaut:
Converting to meters
Using Universal Gravitation equation:
Plugging in values:
Example Question #53 : Universal Gravitation
Mass of Jupiter:
Universal gravitation constant:
Radius of Jupiter:
A marble is placed from the surface of Jupiter. Determine the acceleration due to the gravity of Jupiter.
None of these
Using
and
Combining equations
Solving for
Plugging in values:
Example Question #56 : Universal Gravitation
Mass of Pluto:
Radius of Pluto:
A spring of rest length is placed upright on Pluto. A mass of is gently placed on top and the spring contracts by . Determine the spring constant.
None of these
First, estimate the acceleration due to gravity close to Pluto's surface:
Combining equations and solving for the acceleration:
Plugging in values:
Using
Solving for
Converting to and plugging in values:
(Since the mass is at rest, the acceleration and thus the net force is zero)
Example Question #54 : Universal Gravitation
Mass of Mars:
Radius of Mars:
A spring of rest length is placed upright on Mars. A mass of is gently placed on top and the spring contracts by . Determine the spring constant.
None of these
First, estimate the acceleration due to gravity close to the martian surface:
Combining equations and solving for the acceleration:
Plugging in values:
Using
Solving for
Converting to and plugging in values:
(Since the mass is at rest, the acceleration and thus the net force is zero)
Example Question #55 : Universal Gravitation
Determine the surface gravitational constant for a roughly spherical asteroid of mass and a radius of .
None of these
Setting universal gravitation equal to the surface gravitational approximation
Where will be the surface gravitational acceleration constant
Solving for
Plugging in values
Example Question #56 : Universal Gravitation
Determine the surface gravitational constant for a roughly spherical asteroid of mass and a radius of .
None of these
Setting universal gravitation equal to the gravitational approximation
Where will be the surface gravitational acceleration constant
Solving for
Converting to and plugging in values
Example Question #57 : Universal Gravitation
Astronauts have recently detected a new exoplanet, Zina. The mass of the planet is twice that of Earth, and the radius is three times larger than Earth's radius. What fraction of our gravity is experienced on this planet?
Same gravity because gravity is constant.
The gravity equation is:
, where is the universal gravitation constant, is the mass of the planet, and is the radius of planet. To find a ratio between the gravity on the planet Zina and our planet, we need to plug in the relevant information:
Remember, we are doing a ratio, so if we reference everything in terms of Earth numbers, the bottom fraction becomes much simpler and cancels out with the top fraction. Also, the gravitational constant is constant, so it cancels out. Therefore, the only important information are the ratios the mass and radius differ from Earth's.
Example Question #61 : Universal Gravitation
Radius of the moon:
Mass of moon:
Jennifer is piloting her spaceship around the moon. How fast does she need to go to oribit the moon above the surface.
The radius of the orbit will be the radius of the moon plus the altitude of the orbit.
Converting to and plugging in values:
Centripetal force will need to equal universal gravitational force
Solving for velocity
Plugging in values:
Example Question #91 : Forces
For a planet of mass and diameter what is the force of gravity on an object of mass ?
To solve this we use the universal gravitation formula
where G is the gravitational constant
and r is the radius of the planet
plugging everything in we get
Example Question #62 : Universal Gravitation
In a fictional universe, two planets exist: one with a mass of and diameter of , the other with a mass of and diameter of . The two planets' closest surfaces to one another are separated by a distance of . Assuming that the gravitational constant in this universe, , is , what is the gravitational force between the two planets?
This question tests your understanding of gravitational force between two objects, and your ability to apply the formula for gravitational force.
The formula for gravitational force is as follows:
In this example, we are asked to explicitly solve for the gravitational force between the two planets in this alternative universe. We are given the values for , , and . To solve for the gravitational force between the planets, we must first calculate the value of , or the distance between the centers of each planet. We are given the values of the diameters of each of the planets, and therefore, if we divide each value by , we have the values of the radii for each planet. To calculate the distance between the centers of the two planets, we must add the values of each planet's radius together, in addition to the distance between the closest surfaces of the planets. Thus, . After completing the arithmetic, you find that .
Now, you have each of the relevant values to plug into the gravitational force formula. The calculation is shown below:
Therefore, the gravitational force between the two planets is .