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Physics Exam 1 Key Concepts

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이 집합의 용어 (34)

  • What makes a hypothesis scientific?
    A scientific hypothesis must be testable and falsifiable, meaning it can potentially be proven wrong.
  • Difference between scalars and vectors
    Scalars have magnitude only (e.g., speed, mass). Vectors have magnitude and direction (e.g., force, velocity).
  • Which physical quantities are vectors?
    Forces, velocity, and acceleration are vectors.
  • How do two forces acting in the same direction combine?
    They add together to produce a larger resultant force.
  • What is the net force if two equal forces act in opposite directions?
    The net force is zero.
  • State Newton’s First Law
    An object remains at rest or moves with constant velocity unless acted upon by a net external force.
  • What happens if the net force on an object is zero?
    The object maintains constant velocity.
  • Why does friction balance a push when an object moves at constant velocity?
    Because the net force must be zero.
  • What are balanced forces?
    Forces that cancel each other so the net force equals zero.
  • Define acceleration
    Acceleration is the rate of change of velocity: \(a=\frac{\Delta v}{\Delta t}\).
  • Can an object accelerate if its speed is constant?
    Yes, if its direction changes.
  • Why does a car turning a corner accelerate?
    Because its velocity direction changes.
  • What is free fall?
    Motion when gravity is the only force acting.
  • Acceleration due to gravity near Earth’s surface
    Approximately 9.8 m/s² downward.
  • Formula for distance fallen in free fall
    \(d=\frac{1}{2}gt^{2}\).
  • What happens at the highest point of an object thrown upward?
    Velocity is zero but acceleration is still downward.
  • What is mass?
    The amount of matter in an object.
  • What is weight?
    The gravitational force acting on an object: \(W=mg\).
  • How does weight change on different planets?
    Weight changes depending on the gravitational strength, but mass stays constant.
  • State Newton’s Second Law
    Force equals mass times acceleration: \(F=ma\).
  • What does a constant force produce?
    A constant acceleration.
  • How does mass affect acceleration for the same force?
    Larger mass produces smaller acceleration.
  • What is work?
    Work occurs when a force moves an object over a distance: \(W=Fd\).
  • Unit of work and energy
    The Joule (J), where 1 J = 1 N·m.
  • What is kinetic energy?
    Energy an object has due to motion: \(KE=\frac{1}{2}mv^{2}\).
  • Why can energy appear lost in motion problems?
    It is converted into thermal energy due to friction.
  • Which energy sources originate from the Sun?
    Wind, hydroelectric, and fossil fuels.
  • Can gravity do work on an object moving down a slope?
    Yes, because gravity has a component along the slope.
  • Why does the normal force do no work?
    Because it acts perpendicular to the direction of motion.
  • Equation describing gravitational attraction
    \(F=\frac{GMm}{r^{2}}\).
  • What determines the surface gravity of a planet?
    The planet’s mass and radius: \(g=\frac{GM}{R^{2}}\).
  • How were some planets discovered historically?
    By observing disturbances in the orbits of known planets.
  • What is Hooke’s Law?
    The extension of an elastic object is proportional to the applied force: \(F=kx\).
  • Does force determine velocity or acceleration?
    Force determines acceleration, not velocity.