Key Vocabulary
The force that pulls objects with mass toward one another.
Gravity
True or False: Gravity pushes objects away from each other.
False
This measurement stays the same whether you're on Earth, the Moon, or Mars.
Mass
These are the two main factors that determine the strength of gravitational force between objects.
Mass & Distance
This star's enormous mass creates a gravitational field strong enough to hold the entire solar system together.
The amount of matter in an object that does not change based on location.
Mass
This celestial body has enormous mass, which is why objects fall toward it when dropped.
Earth
This measurement changes depending on the strength of the gravitational pull at your location.
Weight
When two objects move farther apart, the gravitational force between them does this.
Weaker/Decreases
A star's massive gravitational pull keeps planets in this type of path instead of letting them drift into space.
Orbit
The region around an object where its gravitational force can be felt.
Gravitational Field
When you drop a ball, Earth pulls the ball downward. According to Newton's third law, the ball also pulls on Earth. Explain why we don't see Earth move toward the ball.
Earth's enormous mass makes its movement too tiny to detec
An astronaut has a mass of 80 kg on Earth. When she travels to the Moon, her mass will be this value.
80 kg Mass does not change with location.
A large planet and a small moon are the same distance from a spacecraft. The spacecraft will experience a stronger gravitational pull from this object.
Large Planet
Astronomers observe a star "wobbling" slightly in its position. Explain what causes this wobble and what it reveals about the star's surroundings.
orbiting planets tugging on the star with their own gravitational pull. The wobble reveals the presence and mass of planets orbiting the star.
A student says their mass changed when they went to the top of a mountain. This statement shows a confusion between mass and this what other measurement.
Weight
A classmate claims that gravity only exists on planets. Use evidence about objects with mass to explain why this is a misconception.
Any object with mass creates a gravitational field, so gravity exists everywhere in the universe, not just on planets
You step on a scale on Earth and it reads 150 pounds. You then travel to a planet with twice Earth's mass. Explain what happens to your weight and why, while your mass remains constant.
Your weight increases (to approximately 300 pounds) because the stronger gravitational field pulls on your mass more forcefully
Two identical satellites orbit Earth. Satellite A orbits at 400 km altitude, while Satellite B orbits at 800 km altitude. Compare the gravitational force each satellite experiences and explain your reasoning using the relationship between distance and gravity.
Satellite A experiences stronger gravitational force because it is closer to Earth, and gravitational force becomes weaker as distance increases
Engineers are planning a mission to Mars and need to calculate how much fuel a rocket requires to escape Earth's gravity. Explain why understanding gravitational fields is essential for this calculation.
What is they need to know the strength of Earth's gravitational field to determine the force the rocket must overcome.
Two students are debating whether a pencil has gravity. One says no because it doesn't pull things toward it. Using the vocabulary term "gravitational field," explain why the pencil does create gravity even though we can't feel it.
The pencil has mass, so it creates a gravitational field, but the field is extremely weak because the pencil's mass is very small.
Two asteroids are floating in space, each with a mass of 1,000 kg, separated by 10 meters. Describe what happens to these asteroids over time and explain why, even though the effect is extremely small.
The asteroids slowly pull toward each other because all objects with mass exert gravitational attraction on one another
A student argues that astronauts are "weightless" in space, so they must have no mass. Identify the error in this reasoning and explain the difference between having no weight and having no mass.
The student confuses weight with mass? (Astronauts in orbit experience very weak gravitational pull, making their weight nearly zero, but their mass—the amount of matter they contain—remains unchanged
A space probe is traveling from Earth toward Jupiter. Describe how the gravitational forces from both planets change as the probe moves.
Earth's gravitational pull weakens as the probe moves away (increasing distance), while Jupiter's pull strengthens as the probe approaches (decreasing distance)
Engineers are planning a mission to Mars and need to calculate how much fuel a rocket requires to escape Earth's gravity. Explain what would happen if they underestimated the fuel needed.
Underestimating fuel would mean the rocket couldn't generate enough force to escape and would fall back to Earth