Forces & Motion

Main Ideas:

• Motion: An object is in motion if its position changes relative to a reference point. Velocity includes both speed and direction.

• Acceleration: Refers to increasing, decreasing speed, or changing direction. Unbalanced forces cause changes in motion, while balanced forces do not.

• Friction: A force that opposes motion, acting as either static (not moving) or kinetic (moving). It slows down objects, and its strength depends on the surfaces in contact.

• Gravity: The force of attraction between objects, influenced by mass and distance. Sir Isaac Newton for this relationship. Weight varies with gravity, while mass remains constant.

• Terminal Velocity: Achieved when air resistance equals gravity, resulting in constant speed during free fall.

• Free-body Diagrams (FBDs): Illustrate the size and direction of all acting forces on an object.

• Newton's Laws of Motion: A set of three fundamental principles that describe the relationship between a body and the forces acting on it, as well as the body's motion in response to those forces.

• Equations and Examples:

  • Speed calculation: velocity is speed with direction.

  • Net Force: Resultant force acting on an object when balanced and unbalanced forces are applied.

  • Examples include calculating net forces in various scenarios and using graphs to represent motion.

• Key Types of Forces: Friction, gravity, and air resistance significantly influence motion, with projectile motion combining vertical and horizontal motions.