Understanding Forces: Gravity, Friction, and Motion

• Forces are explored via gravity, friction, electric forces, and magnetic forces.

Big Idea

• How forces change an object's motion is the central theme.

Gravity and Friction

• Key questions include identifying contact and non-contact forces.
• Examination into universal gravitation and the effect of friction.

Types of forces

• Force is a push or pull on an object, measured in newtons (N).
• Contact force examples: pushing a container or the friction from pressing on keys.
• Non-contact force examples: gravity, magnetism, and electricity.

Friction

• Friction resists the motion of two touching objects.
• Static friction prevents objects from sliding past each other.
• Sliding friction opposes the motion of objects sliding past each other.
• Fluid friction occurs between a surface and a fluid, such as water or air (air resistance).

Gravity

• Gravity is an attractive force existing between objects with mass.
• Mass is the amount of matter that has mass.
• The more mass, the stronger the gravitational pull.
• The greater the distance, the weaker the gravitational pull.

Weight vs. Mass

• If an astronaut weighs 539N and has a mass of 55kg on Earth, the weight would vary on the moon.

Electrical Force

• Static charge involves an imbalance of positive or negative charge on an object. -Variables affecting electric charge are the amount of charge and distance.
• Opposite charges attract, while same charges repel.
• The greater the charge, the greater the electric force.
• The greater the distance, the lesser the electric force.

Magnetic Force

• Magnet attracts metal iron.
• Magnetic Pole: place on a magnet where the force is the strongest.
• Opposite poles attract, and the same poles repel.
• Magnetic strength is affected by the size of the magnet and distance.
• The further away the magnets are, the weaker the magnetic force.

Explore the fundamental types of forces, including gravity, friction, electric, and magnetic forces. Learn how these forces influence an object's motion, distinguishing between contact and non-contact forces and their real-world effects.