Physics - Topic 15 - Forces and Matter

• What are the three types of deformation mentioned?

  Elastic deformation, plastic deformation, and linear elastic distortion
• What happens when a single force is applied to an object?

  The object will just move in the force’s direction
• What occurs when a spring is forced inwards from opposite sides?

  The spring will compress
• What is the reaction force when one end of a spring is fixed and a force is applied at the other end?

  A reaction force from the fixed point is applied to the spring
• What does deformation mean?

  Changing shape
• What is elastic deformation?

  The object returns to its original shape when the load is removed
• Give an example of elastic deformation.

  An elastic band
• What is plastic deformation?

  The object does not return to its original shape when the load is removed
• Give an example of plastic deformation.

  A spring when pulled too far
• What is the formula for Hooke's Law?

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

  The force required to extend a spring per metre
• What do the variables \( F \), \( k \), and \( x \) represent in Hooke's Law?

  F is the force applied, k is the spring constant, and x is the extension
• What does it mean if a spring follows Hooke's Law?

  The extension of the spring is directly proportional to the force applied
• What does the gradient represent on a Force/Extension graph?

  The gradient is the spring constant \( k \)
• What is the elastic limit of a spring?

  The point at which it stops being linear and does not obey Hooke’s Law
• What characterizes a non-linear section on a Force/Extension graph?

  It does not follow Hooke’s Law and indicates plastic deformation

  
• What happens if the graph is just linear with no non-linear end section?

  The material is brittle and snaps instead of stretches after the elastic limit
• How is work done calculated in relation to a spring?

  Work Done = \(\frac{1}{2} k x^2\)
• What is atmospheric pressure?

  The total weight of the air above a unit area at a certain altitude
• How does atmospheric pressure change with altitude?

  It decreases with increasing height above the Earth’s surface
• What causes atmospheric pressure?

  The weight of the air is the force which causes the pressure
• Why is there less pressure at higher elevations?

  There are fewer air molecules above the unit area
• What is a fluid?

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

  The air exerts an inward force on the outer surface of the balloon
• What happens if the inward force on a balloon is greater than the outward force?

  The balloon will collapse
• What occurs in space regarding atmospheric pressure and balloons?

  There is lower atmospheric pressure, allowing the balloon to expand
• What happens when you blow into a balloon?

  It increases the amount of collisions the balloon surface experiences, raising the pressure inside
• What does pressure in a fluid cause?

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

  The greater the depth, the greater the pressure
• How does fluid density affect pressure?

  The denser the fluid, the greater the pressure
• What is the condition for an object to float?

  An object floats if its weight is less than the weight of the water it displaces
• How does a boat float in water?

  A 1000kg boat will sink until it displaces 1000kg of water
• What is the buoyancy force?

  The upwards force that counteracts the weight of the floating object
• What is the relationship between buoyancy force and the weight of the fluid displaced?

  The buoyancy force is equal to the weight of the fluid displaced by the object
• Why does a ping pong ball float on water?

  Its density is less than the density of the water
• What happens to pressure as depth increases in a liquid?

  The greater the depth, the greater the weight of the water above, leading to greater pressure
• What is the formula for pressure due to a column of liquid?

  Pressure = height of column × density of liquid × g