https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:space-science/x0e04e0cb682fb793:untitled-899/v/introduction-to-gravity 2023-04-30T21:01:15.828786566Z Introduction to gravity Newton's Law of Universal Gravitation describes the strength of gravitational attraction between two objects. The gravitational force is equal to the mass of object 1 times the mass of object 2, divided by the distance between the objects squared, all times the gravitational constant (G). G is small, so the force is only noticeable if one or both objects are very massive. Sal Khan video https://cdn.kastatic.org/googleusercontent/srnSzuP3zeDJn0bLL0RLU6YOMhZCPgv7nIJBagq80fxiCqd6gmvfB7ee-wsxH4m3L3cF9mXXnYX6fjIefUlZ-Vdr4A Introduction to gravity Newton's Law of Universal Gravitation describes the strength of gravitational attraction between two objects. The gravitational force is equal to the mass of object 1 times the mass of object 2, divided by the distance between the objects squared, all times the gravitational constant (G). G is small, so the force is only noticeable if one or both objects are very massive. https://cdn.kastatic.org/ka-youtube-converted/Xcel427Ezl0.mp4/Xcel427Ezl0.mp4 943 Gravity https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:kinematics/x0e04e0cb682fb793:free-fall-acceleration/v/falling_objects 2024-07-01T11:54:52.194339821Z Falling objects If two objects are dropped from the same height in a vacuum, they accelerate at the same rate and hit the ground at the same time. This happens because an object's gravitational mass is equal to its inertial mass. As a result, any object in free fall near Earth's surface accelerates at 9.81 m/s/s. The gravitational force acting on an object is not always equal to its weight. A free falling object experiences a gravitational force, but also appears weightless because there is no normal force pushing up on it. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/0bd1ac14-c51e-4071-9ff6-169a419b63d5_1280_720_base.png Falling objects If two objects are dropped from the same height in a vacuum, they accelerate at the same rate and hit the ground at the same time. This happens because an object's gravitational mass is equal to its inertial mass. As a result, any object in free fall near Earth's surface accelerates at 9.81 m/s/s. The gravitational force acting on an object is not always equal to its weight. A free falling object experiences a gravitational force, but also appears weightless because there is no normal force pushing up on it. https://cdn.kastatic.org/ka-youtube-converted/wf8SYTb4r-g.mp4/wf8SYTb4r-g.mp4 700 Gravity https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:mass-weight-and-density/x0e04e0cb682fb793:gravitational-field/e/understand-gravitational-forces 2026-06-30T16:30:41.535282189Z Understand: Gravitational force Check your understanding of gravitational force in this set of free, standards-aligned practice questions. Khan Academy exercise https://www.khanacademy.org/science/up-sw-class-9-science-bridge-course/x2164f6ec11d6a504:week-4/x2164f6ec11d6a504:untitled-130/v/gravitational-forces-ms 2024-01-04T21:41:56.674101033Z Gravitational forces Gravity is more than just things falling down. It's an attractive force that exists between any two objects with mass. Every object with mass, like Earth or a lamp, has a gravitational pull. The strength of this pull depends on the mass of the objects and the distance between them. Even the moon feels Earth's gravity, which is why it orbits us. Khan Academy video https://cdn.kastatic.org/ka_thumbnails_cache/ea4aa5db-9a82-421a-be91-0776a2a66cc3_1280_720_base.png Gravitational forces Gravity is more than just things falling down. It's an attractive force that exists between any two objects with mass. Every object with mass, like Earth or a lamp, has a gravitational pull. The strength of this pull depends on the mass of the objects and the distance between them. Even the moon feels Earth's gravity, which is why it orbits us. https://cdn.kastatic.org/ka-youtube-converted/atogJ2qw9Ko.mp4/atogJ2qw9Ko.mp4 220 Gravity https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:mass-weight-and-density/x0e04e0cb682fb793:gravitational-field/a/gravitational-forces 2026-04-26T16:30:39.382257956Z Learn and try: Gravitational force Use a PhET simulation to investigate the gravitational forces two masses exert on each other. Explore how mass and distance affect the strengths of gravitational forces. article https://www.khanacademy.org/science/ms-physics/x1baed5db7c1bb50b:teacher-resources/x1baed5db7c1bb50b:hands-on-physics-activities/a/activity-how-can-a-skydiver-fall-safely 2026-02-27T18:00:31.886851552Z Activity: How can a skydiver fall safely? Make science come alive in your classroom with this free hands-on activity aligned to middle school standards. article https://www.khanacademy.org/science/ap-physics-c-mechanics/x077f5683c1428fac:kinematics/x077f5683c1428fac:free-fall/a/free-fall 2026-05-01T14:10:52.97313295Z Learn and try: Free fall Learn what it means for an object to be in free fall. Describe free fall motion using visual and mathematical models. article https://www.khanacademy.org/science/in-in-class11th-physics/in-in-class11th-physics-motion-in-a-straight-line/in-in-class11-objects-in-freefall/a/freefall-ap1 2021-04-29T07:47:36Z Freefall review Review the key concepts and skills for acceleration due to gravity, including analyzing motion of objects in freefall. article https://www.khanacademy.org/science/cambridge-o-level-physics-cie/x0e04e0cb682fb793:mass-weight-and-density/x0e04e0cb682fb793:mass-and-weight/a/what-is-weight 2025-02-28T00:12:11.735240474Z What is weight? Weight is another word for the force of gravity. article