Topic 15-Forces and Matter

• What are the three types of deformation mentioned?

  Stretching, bending, and compressing
• What happens when a single force is applied to an object?

  The object moves in the force's direction
• What occurs when forces are applied inwards from opposite sides?

  The object compresses
• What is a reaction force in the context of a spring?

  A force from the fixed point of the spring
• What does deformation mean?

  Changing shape
• What is elastic deformation?

  The object returns to its original shape
• What is plastic deformation?

  The object does not return to its original shape
• What is the formula for Hooke's Law?

  F = kx
• What does the spring constant k represent?

  Force required to extend a spring per metre
• What does F represent in Hooke's Law?

  The force applied to the spring
• What does k represent in Hooke's Law?

  The spring constant
• What does x represent in Hooke's Law?

  The extension of the spring
• What does Hooke's Law state about the extension of a spring?

  It is directly proportional to the force applied
• What does a linear section on a Force/Extension graph indicate?

  The material is elastic and follows Hooke's Law

  
• What is the gradient of the linear section on a Force/Extension graph?

  K, the spring constant
• What is the elastic limit?

  The point where the material stops being linear
• What does a non-linear section on a Force/Extension graph indicate?

  The material does not follow Hooke's Law
• What happens if the graph is linear with no non-linear end section?

  The material is brittle and snaps
• What is the formula for work done in terms of a spring?

  Work Done = $\frac{1}{2} kx^2$
• What is atmospheric pressure?

  Total weight of air above a unit area
• How does atmospheric pressure change with altitude?

  It decreases with increasing height
• What causes atmospheric pressure?

  The weight of the air above
• Why is there less pressure at higher elevations?

  Fewer air molecules above the unit area
• What is a fluid?

  A liquid or a gas
• How does pressure in a gas depend on atmospheric pressure?

  It depends on the inward force exerted
• What happens to a balloon in space?

  It expands due to lower atmospheric pressure
• What happens when you blow into a balloon?

  Increases collisions and pressure inside
• What does pressure in a fluid cause?

  A force perpendicular to any surface
• How does pressure vary with depth in a fluid?

  Greater depth means greater pressure
• How does fluid density affect pressure?

  Greater density means greater pressure
• What is the condition for an object to float?

  Weight less than displaced water weight
• How does a boat float in water?

  It displaces its weight in water
• What is the buoyancy force?

  The upwards force counteracting weight
• What does the buoyancy force equal?

  Weight of the fluid displaced
• Why does a ping pong ball float on water?

  Its density is less than water's density
• How does increasing depth affect pressure?

  Greater depth means greater pressure felt
• What is the formula for pressure due to a column of liquid?

  Pressure = height × density × g
• What are the key concepts of springs and deformation?

  • Stretching, bending, compressing
  • Elastic deformation: returns to original shape
  • Plastic deformation: does not return to original shape
  • Hooke's Law: F = kx
  • Work Done = $\frac{1}{2} kx^2$
• What are the factors influencing atmospheric pressure and fluid pressure?

  • Atmospheric pressure decreases with altitude
  • Pressure in a fluid depends on depth and density
  • Buoyancy force counteracts weight of floating objects
  • An object floats if its weight is less than displaced water weight