Physics Chapter 4 Test Flashcards

Forces and Motion

• Force: Defined as a push or pull exerted on an object.
• Free Body Diagram: A physical model representing all forces acting on a system.
• One Pound: Equivalent to 4.5 Newtons (N).
• Net Force: The vector sum of all forces on an object, represented as ( F_{net} = F_{scale} + (-F_g) ).

Newton's Laws of Motion

• Newton's 1st Law: An object at rest remains at rest, and an object in motion continues in a straight line with constant speed, unless acted upon by a net force equal to zero.
• Newton's 2nd Law: Expressed as ( a = \frac{f}{m} ), the acceleration of an object is proportional to the net force applied and inversely proportional to its mass.
• Newton's 3rd Law: States that forces in an interaction pair are equal in magnitude and opposite in direction, represented as ( F = -F ).

Key Concepts of Motion

• Inertia: The property of an object to resist changes in its state of motion; an object at rest tends to stay at rest.
• Equilibrium: Occurs when the net force on an object is zero, resulting in no acceleration.
• Apparent Weight: The perceived weight of an object due to all acting forces, resulting in its acceleration.

Special Conditions

• Weightlessness: A state where no contact forces counteract gravity, leading to an apparent weight of zero.
• Drag Force: The resistance force exerted by a fluid on an object moving through it.
• Terminal Velocity: The constant velocity reached when the drag force equals the gravitational force acting on the object.

Forces in Various Contexts

• Interaction Pair: Two forces acting in opposite directions with equal strength.
• Tension: The pulling force transmitted through a string, rope, or cable, calculated with ( T = F_{net} + F_g ).
• Normal Force: The perpendicular force exerted by a surface, calculated as ( F_n = F_g - F ).

Acceleration Scenarios

• Acceleration in an Elevator: No acceleration results in ( F = mg); with acceleration, the equation becomes ( F = m(a + g) ).

Types of Forces

• Friction: Force opposing motion between surfaces in contact.
• Normal Force: Support force from a surface onto an object.
• Spring Force: Force exerted by a compressed or stretched spring.
• Tension: Pulling force transmitted via strings or ropes.
• Thrust: Forces generated to propel objects, especially in rockets or airplanes.
• Weight: The force of gravitational attraction acting on an object.