Gravity & Free Fall | Forces & Motion | Physics | FuseSchool
What Forces Act on a Thrown Ball?
Understanding Gravity's Role
- When a ball is thrown upwards, the only force acting on it after release is the downward force of gravity, which slows it down until it stops and then accelerates it back down.
- Without gravity, a thrown ball would continue in the direction of the throw indefinitely. Gravity is essential for keeping objects like moons and planets in orbit.
Historical Context of Gravity
- Isaac Newton first proposed the concept of gravity in his 1680s work "Principia," introducing the universal law of gravitation after observing an apple fall from a tree.
- Newton theorized that gravity acts on all masses (e.g., apples, planets), with its strength increasing as mass increases and decreasing with distance squared.
Characteristics of Gravitational Force
- Gravity is an attractive force that weakens over long distances; it's this gravitational pull between Earth and the Sun that keeps Earth in orbit.
- The International Space Station (ISS) experiences microgravity because it orbits Earth due to gravitational forces, not because there’s no gravity present.
Experiments Demonstrating Weightlessness
- A simple experiment using a feather and coin in a jar illustrates weightlessness: when both are thrown upward together, they appear to float due to free fall.
Misconceptions About Gravity
- People often misunderstand weightlessness as being caused by zero gravity; however, gravity is always acting even during free fall.
- Everyday objects also exert gravitational forces on each other, but these forces are negligible unless they are significantly distant from larger masses.