27 Questions
Who is credited with proposing the law of universal gravitation?
Isaac Newton
What is the physical significance of the gravitational field?
It creates a force that attracts objects towards the center of the Earth
What does Newton's law of gravitation state about the force between two objects?
It is inversely proportional to the square of the distance between their surfaces
Which interaction is NOT one of the four fundamental interactions?
Kinetic interaction
Which of the following is the general expression for gravitational potential energy?
$U = -\frac{G M m}{r}$
What is the universal gravitation constant (G) approximately equal to?
$6.67 \times 10^{-11}$ N m2/kg2
What is the gravitational force between two objects that are 1.50 x 10^-1 m apart if the mass of one object is 40 kg?
Fg = 4.80 x 10^-6 N
If an object has a mass of 8.0 kg, what is its weight on Earth's surface?
98.4 N
What is the gravitational potential energy of a 2.5 kg object when it is 4.0 m above the ground?
U = 98.4 J
What is the mass of an object if it experiences a gravitational force of 2.0 x 10^-5 N at a distance of 0.75 m from another object?
0.35 kg
If a tower is 30.0 m high and a mass of 50 kg is at the top, what is its gravitational potential energy?
14700 J
What gravitational force does a 60 kg object experience when it is 2.0 x 10^3 m above the surface of the Earth?
$Fg = 1177 N$
A body of mass 75 kg moves to a height of 8 m above the ground. What is its gravitational potential energy?
$U = 6080 J$
What is the value of Earth's acceleration due to gravity in m/s^2?
$9.8$
$7$ kg and $10$ kg objects are $2$ meters apart. What is the gravitational force between them?
$Fg = 4.51 x 10^-10 N$
What did Johannes Kepler summarize with three statements in the early 1600s?
The carefully collected data of Tycho Brahe
Which law of planetary motion states that the orbit of a planet around the sun is an ellipse with the sun at one focus?
Law of Ellipses
According to Kepler's second law of planetary motion, what does the planet do as it moves around the sun?
Sweeps out equal areas in equal interval of time
What does Kepler's third law of planetary motion state about the ratio of the periods and mean distances of planets revolving around the sun?
The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their mean distances
In Kepler's second law, what does 'a line drawn from the sun to the planet sweeps out equal areas' imply about the planet's speed?
It varies as it moves around the sun
Who formulated the three laws on planetary motion?
Johannes Kepler
According to Kepler's law of harmonies, what is the orbital period of a planet located 2.5 x 10^11 m away from the sun?
18.92 years
If a planet has an orbital period of 12.50 years, what is its mean distance from the sun?
1.35 x 10^11 m
What is the orbital period of a planet located at a mean distance of 3.0 x 10^11 m from the sun?
8.60 years
If a planet has an orbital period of 20 years, what is its mean distance from the sun?
4.89 x 10^11 m
According to Kepler's law of harmonies, what would be the orbital period of a planet located at a mean distance of 4.5 x 10^11 m from the sun?
32.00 years
If a planet is located at a mean distance of 6.0 x 10^11 m from the sun, what would be its orbital period according to Kepler's law?
46.40 years
Study Notes
Gravity and Gravitational Interactions
- The law of universal gravitation was proposed by Sir Isaac Newton.
- The gravitational field has physical significance as it is a region around a mass where the gravitational force can be detected.
- Newton's law of gravitation states that the force between two objects is proportional to the product of their masses and inversely proportional to the square of the distance between them.
- The four fundamental interactions do not include the gravitational force between two objects.
- The general expression for gravitational potential energy is U = mgh, where m is the mass, g is the acceleration due to gravity, and h is the height.
- The universal gravitation constant (G) is approximately equal to 6.67408e-11 Nm^2/kg^2.
- The gravitational force between two objects depends on their mass and distance.
Gravitational Potential Energy
- The gravitational potential energy of an object is its energy due to its position in a gravitational field.
- The gravitational potential energy of a 2.5 kg object at a height of 4.0 m is 98 J.
- The gravitational potential energy of a 50 kg object at a height of 30.0 m is 14700 J.
Weight and Gravitational Force
- The weight of an object is the force exerted on it by gravity.
- The weight of an 8.0 kg object on Earth's surface is approximately 78.4 N.
- The gravitational force between two objects depends on their mass and distance.
Kepler's Laws of Planetary Motion
- Johannes Kepler summarized the paths of the planets around the sun with three statements in the early 1600s.
- Kepler's first law states that the orbit of a planet around the sun is an ellipse with the sun at one focus.
- According to Kepler's second law, the planet moves faster when it is closer to the sun and slower when it is farther away, and a line drawn from the sun to the planet sweeps out equal areas.
- Kepler's third law states that the ratio of the periods and mean distances of planets revolving around the sun is a constant.
- Kepler's law of harmonies states that the orbital period of a planet is proportional to the 3/2 power of its mean distance from the sun.
Test your understanding of essential learning competencies in physics related to gravity. This quiz covers Newton’s law of gravitation, gravitational force, weight, acceleration due to gravity, gravitational field, and gravitational potential energy.
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