Upthrust

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

  Pressure due to a column of liquid
• What happens when holes are made in the side of a water container?

  Water squirts out, further from the bottom hole
• Why does water from the bottom hole squirt out further than from the top hole?

  Because the bottom water is at higher pressure
• What is the formula to calculate the pressure of a column of liquid?

  Pressure = height × density × gravitational strength
• What values are provided in the exam for calculating pressure?

  Density and gravitational field strength
• If a freshwater lake has a depth of 8 meters, what is the pressure at the bottom?

  78,400 Pascals
• How does pressure change with depth in a liquid?

  Pressure increases with depth
• How does pressure change with the density of a liquid?

  Pressure increases with density
• What is upthrust in relation to floating and sinking objects?

  It is the resultant upward force on an object
• What must upthrust equal for an object to float?

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

  The object sinks
• What occurs when an object is lowered into water?

  The water level lowers due to displacement
• What is the size of the upthrust acting on an object?

  It equals the weight of water displaced
• What must an object do to float in water?

  Displace its own weight of water
• What happens when an object is less dense than water?

  It floats after displacing small volume
• What happens when an object has the same density as water?

  It floats at the water's surface
• What occurs when an object is more dense than water?

  It sinks because it can't displace enough water
• Where can you find more questions on pressure in liquids?

  In the vision workbook
• What factors influence whether an object floats or sinks?

  Density of the object and water displaced
• What is buoyancy in relation to floating objects?

  It is the upward force acting on submerged objects
• How does gravitational field strength affect pressure in liquids?

  Higher gravitational strength increases pressure