Science, Grade 6


Table Of Contents: Gravity

1. Law of Universal Gravitation
The law of universal gravitation, proposed by Sir Isaac Newton, states that all objects in the universe attract each other through gravity. Gravity is a type of force that pulls objects toward each other. The amount of gravitational force between two objects depends on their masses and the distance between them. The strength of gravity increases as mass increases, and the strength of gravity decreases as the distance between objects increases.
2. Mass and Weight
An object’s mass refers to the amount of matter an object contains, while an object’s weight is the measure of the effect of gravity on its mass. The mass of a person is the same on the Moon and the Earth, but the person weighs less on the Moon than the Earth because the Moon exerts a smaller gravitational force than the Earth.
3. Gravity and Motion
When gravity is the only force acting on an object, the object is said to be in free fall. This can be observed if objects are placed in a vacuum. On Earth, all objects in free fall accelerate at the same rate of 9.8 m/s2, even if the objects have different masses. Typically, objects don’t fall within a vacuum, but instead they fall through the air and experience resistance, which is a type of fluid friction acting in the opposite direction of gravity. Objects with greater surface area will experience more air resistance and accelerate more slowly than objects with less surface area.