chapter 3

• force


  push and pull due to interactions between objects to explain changes in motion

  can be classified into contact and non-contact forces
• gravitational force

  the pull exerted by Earth's gravity on any object
• electrostatic force

  the attractive or repulsive forces between electric charges
• magnetic force

  attractive or repulsive force between magnets
• friction

  force that opposes or tends to oppose motion between surfaces in contact
• air resistance


  frictional force exerted by air that opposes the motion of moving objects
• normal force


  the push exerted by a surface on an object pressing it, push is always perpendicular to the surface
• tension

  pull exerted by a stretched string, spring or rope on an object attached to it
• mass

  a property that does not change with its location or shape, dependent on the number and composition of atoms and molecules that make up the body
• gravitational force due to gravitational field strength

  gravitational force is the stronger at the surface of the Earth

  gravitational force weakens as it gets further away from the surface of Earth due to decreasing gravitational field strength
• weight

  dependent on the gravitational field strength at a certain location

  weight of an object is directly proportional to its mass
• properties of mass


  amount of matter

  scalar quantity

  si unit is kilogram

  independent of gravitational field strength

  measured with a beam balance or calibrated electronic balance
• properties of weight

  gravitational force

  vector quantity

  si unit is newton

  dependent on the gravitational field strength

  measured with spring balance
• What is electrostatic force?

  Attractive or repulsive forces between charges
• Why is magnetic force considered a non-contact force?

  Because magnets interact without touching each other
• What is a force?

  A push or pull between objects
• What is the term used to describe the upward force exerted by a surface to support an object?

  Normal force
• What factors influence the magnitude of air resistance?

  Object's speed and shape
• What are the characteristics of gravitational force?

  • Non-contact force
  • Acts at a distance
  • Always draws objects towards Earth's center
• What are the two classifications of forces?

  • Contact forces: require physical touch (e.g., friction)
  • Non-contact forces: act at a distance (e.g., gravitational force)
• How does a force affect motion?

  It causes changes in the motion of objects
• What is static friction?


  It prevents objects from starting to move
• What is the effect of gravitational force on a person?

  It determines their weight
• What are the two types of friction?

  Static and kinetic friction
• What happens when like poles of magnets are brought together?

  They repel each other
• What occurs when opposite charges interact?

  They attract each other
• What is the relationship between normal force and friction?

  • Friction opposes motion between surfaces
  • Normal force is the perpendicular force
  • Increased normal force results in increased friction
• What is the direction of the normal force acting on the object by the table?


  Upwards
• How does friction act between surfaces?

  It opposes motion when surfaces contact
• How does speed affect air resistance?

  Faster objects encounter more air resistance
• How does static friction relate to tires?


  It provides grip while standing still
• What is the direction of the normal force acting on the table by the object?


  Downwards
• How do the interactions of magnetic poles differ between like and unlike poles?


  Like poles repel, unlike poles attract
• What are the characteristics of normal force?

  • It is a contact force
  • Acts perpendicular to the surface
  • Supports the weight of the object
• What is the normal force?

  A perpendicular push by a surface
• What is gravitational force?

  The pull exerted by Earth's gravity
• What type of force is electrostatic force?

  Non-contact force
• What is the relationship between air resistance and motion?

  • Air resistance opposes the motion of objects
  • It acts on objects moving through the atmosphere
  • It slows down the objects as they travel
• What is magnetic force?

  Attractive or repulsive force between magnets
• What happens when like charges interact?

  They repel each other