Physics: Free-Body Diagrams Quiz

Forces and Motion

• A force is defined as a push or pull on an object resulting from its interaction with others.
• Applied forces can change an object's motion, direction, size, or shape and are vector quantities with both magnitude and direction.
• Forces can be classified into two types: contact forces (e.g., friction, air resistance) and non-contact forces (e.g., gravitational, magnetic).
• Free-body diagrams help visualize forces acting on an object by representing them as vector arrows, showing magnitude and direction.

Balanced and Unbalanced Forces

• Balanced forces occur when the sum of all forces acting on an object is zero, resulting in no change in motion.
• Unbalanced forces cause acceleration, contradicting Newton's first law, which states objects in motion stay in motion unless acted upon.
• For balanced situations along the x and y axes, opposing forces equal each other, such as a 4 N weight being countered by a 4 N normal force.

Newton's Laws of Motion

• Newton's first law (law of inertia) states that an object remains at rest or in uniform motion unless influenced by an unbalanced force.
• Newton's second law relates force, mass, and acceleration with the formula: Force = Mass × Acceleration.
• An object's resistance to changes in motion is called inertia; more mass results in greater inertia.

Mass vs. Weight

• Mass is a scalar quantity representing the amount of matter in an object and remains constant regardless of location.
• Weight is a vector quantity reflecting the gravitational force acting on an object, calculated by multiplying mass by gravitational acceleration.
• Weight varies with gravitational pull and is given in Newtons (N), whereas mass is typically in kilograms (kg).

Measurement Units and Conversion

• Metric units for weight include grams, kilograms, and metric tons. For example, one kilogram equals 1,000 grams.
• U.S. weight measurements include ounces, pounds, and tons, with specific conversion rates between them, such as 16 ounces in a pound.

Volume and Density

• The volume of a rectangular prism can be calculated using length, width, and height.
• For irregular objects, volume can be determined using the water displacement method to find the volume displaced.
• Density quantifies how compact an object is and is calculated as density = mass / volume (kg/m³).
• Density influences various phenomena, such as floating and sinking in fluids, with solids typically being denser than liquids and liquids denser than gases.

Buoyancy

• Buoyancy is the property allowing objects to float in fluids, with upward buoyant force created due to fluid pressure, which increases with depth.
• Archimedes' Principle states that the buoyant force equals the weight of the displaced fluid, allowing calculations of buoyant force based on density, volume, and gravitational acceleration (9.8 m/s²).