Floating or Sinking (T)

• What should you be able to calculate by the end of the video?

  Calculate the pressure due to a column of liquid.
• What should you be able to describe by the end of the video?

  Factors which influence floating and sinking.
• Why does water from the bottom hole squirt out further than from the top hole?

  Because it is at a higher pressure.
• What is the equation to calculate the pressure of a column of liquid?

  Pressure (Pa) = height of the column (m) × density of the liquid (kg/m³) × gravitational field strength (N/kg)
• What values are you given in the exam to calculate pressure?

  Density and gravitational field strength.
• How would you calculate the pressure at the bottom of a freshwater lake with a depth of 8 meters?

  By substituting the values into the pressure equation.
• What is the pressure at the bottom of an 8-meter deep freshwater lake?

  78,400 Pascals.
• Why does the pressure of a liquid increase with depth?

  Because of the greater weight of liquid acting downwards.
• How does the density of a liquid affect its pressure?

  It increases the pressure due to greater weight.
• What is upthrust in the context of floating and sinking objects?

  • Upthrust is the resultant force acting upwards on an object submerged in a liquid.
  • It is caused by the pressure difference between the bottom and top of the object.
• What must be true for an object to float?

  Upthrust must equal the object's weight.
• What happens if the upthrust is less than the object's weight?

  The object sinks.
• What is the relationship between the weight of water displaced and the upthrust acting on an object?

  • The upthrust acting on the object is equal to the weight of the water displaced by the object.
• What does it mean if an object can displace its own weight of water?

  The upthrust will equal the object's weight, allowing it to float.
• How does the density of an object affect its ability to float?

  • An object less dense than water can float by displacing a small volume of water.
  • An object with the same density as water must displace its own volume to float.
  • An object denser than water cannot displace enough water to float and will sink.