Physics Motion in a Straight Line

Motion in a Straight Line

• Distance: The total path length traveled by an object, regardless of direction.
• Displacement: The shortest distance between the initial and final position of an object, considering direction.
• Speed: The rate at which an object covers distance. It is a scalar quantity. Formula: Speed = Distance / Time
• Velocity: The rate at which an object changes its position. It is a vector quantity. Formula: Velocity = Displacement / Time
• Uniform Motion: An object moving with a constant speed in a straight line.
• Non-uniform Motion: An object moving with a varying speed or changing direction.
• Acceleration: The rate of change of velocity. Formula: Acceleration = Change in Velocity / Time

Uniformly Accelerated Motion

• Constant Acceleration: Acceleration remains constant throughout the motion.
• Equations of Motion: Relate initial velocity (u), final velocity (v), acceleration (a), time (t), and displacement (s) in uniformly accelerated motion.
  • v = u + at
  • s = ut + ½ at²
  • v² = u² + 2as
• Graphical Representation:
  • Velocity-time graph: The slope represents acceleration. The area under the graph gives displacement.
  • Displacement-time graph: The slope represents velocity.
• Free Fall: Vertical motion under the influence of gravity only. Acceleration due to gravity (g) is approximately 9.8 m/s².

Scalars and Vectors

• Scalars: Quantities that have only magnitude (e.g., speed, distance, mass).
• Vectors: Quantities that have both magnitude and direction (e.g., velocity, displacement, force).
• Vector Addition: Graphical and analytical methods (parallelogram law, triangle law) are used to add vectors.
• Vector Subtraction: Subtracting a vector is equivalent to adding the negative of that vector.
• Components of a Vector: Resolving a vector into its components along different directions.

Force and Laws of Motion

• Force: A push or pull that can change the state of rest or motion of an object.
  • Contact Force: Requires physical contact between objects (e.g., friction, normal force).
  • Non-contact Force: Acts at a distance (e.g., gravity, electrostatic force).
• Newton's First Law of Motion (Inertia): An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
• Newton's Second Law of Motion: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Formula: F = ma
• Newton's Third Law of Motion (Action-Reaction): For every action, there is an equal and opposite reaction.

Gravitation

• Gravity: The force of attraction between any two objects with mass.
• Gravitational Force: Depends on the masses of the objects and the distance between them.
• Acceleration Due to Gravity: The acceleration experienced by an object due to the gravitational force of the Earth (or another celestial body).

Work, Energy, and Power

• Work: The product of force and the displacement in the direction of the force. Formula: Work = Force × Displacement × cos(θ) (θ is the angle between force and displacement)
• Energy: The capacity to do work.
  • Kinetic Energy: Energy of motion. Formula: KE = ½ mv²
  • Potential Energy: Energy stored due to position or configuration.
  • Gravitational Potential Energy: Potential energy due to height. Formula: PE = mgh (m = mass, g = acceleration due to gravity, h= height)
• Power: The rate at which work is done. Formula: Power = Work / Time