Gravity Fundamentals

Study Notes

Definition: Gravity is a force that attracts two objects with mass towards each other.
Universal force: Gravity is a universal force that affects everything with mass, from the smallest atoms to the largest galaxies.
Strength: The strength of gravity depends on the mass of the objects and the distance between them.
Gravity on Earth: On Earth, gravity pulls objects towards the center of the planet, which is why objects fall towards the ground.
Weight: Weight is the force exerted on an object by gravity, and it is measured in Newtons (N).

Definition: Friction is a force that opposes motion between two surfaces in contact.
Types of friction:
- Static friction: The force that prevents an object from moving when a force is applied to it.
- Kinetic friction: The force that opposes motion when an object is already moving.
- Rolling friction: The force that opposes motion when an object is rolling on a surface.
- Fluid friction: The force that opposes motion when an object is moving through a fluid (such as air or water).
Factors affecting friction:
- Surface roughness: The rougher the surfaces, the greater the friction.
- Normal force: The greater the normal force (force perpendicular to the surface), the greater the friction.
- Surface area: The greater the surface area in contact, the greater the friction.
Reducing friction: Friction can be reduced by:
- Using lubricants (such as oil or grease)
- Polishing surfaces to reduce roughness
- Reducing the normal force (e.g. by using a ramp instead of a lift)

Gravity is a force that attracts two objects with mass towards each other, making it a universal force that affects everything with mass.
The strength of gravity depends on the mass of the objects and the distance between them.
On Earth, gravity pulls objects towards the center of the planet, causing objects to fall towards the ground.
Weight is the force exerted on an object by gravity, and it is measured in Newtons (N).

Friction is a force that opposes motion between two surfaces in contact, and it has several types.
Static friction is the force that prevents an object from moving when a force is applied to it.
Kinetic friction is the force that opposes motion when an object is already moving.
Rolling friction is the force that opposes motion when an object is rolling on a surface.
Fluid friction is the force that opposes motion when an object is moving through a fluid (such as air or water).
Factors that affect friction include surface roughness, normal force, and surface area.
Surface roughness increases friction, while polishing surfaces can reduce it.
The greater the normal force, the greater the friction.
Increasing the surface area in contact also increases friction.
Friction can be reduced by using lubricants, polishing surfaces, or reducing the normal force.