Liquid pressure & Upthrust

• What is the main topic of the video?

  The calculation of pressure in a liquid and factors affecting whether an object floats or sinks.
• What primarily causes the pressure acting on an object submerged in water?

  Most of the pressure is due to surrounding water molecules colliding with the object.
• How does pressure change as an object moves deeper in water?

  The pressure increases due to the weight of the water above the object.
• What factors determine the pressure in a liquid?

  The density of the liquid and the gravitational field strength.
• What is the equation for pressure in a liquid?

  Pressure (P) = height (h) × density (ρ) × gravitational field strength (g).
• If the height of the water column is 20 meters, the density is 1000 kg/m³, and the gravitational field strength is 9.8 N/kg, what is the pressure?

  The pressure is 196,000 pascals.
• What is the pressure at a depth of 90 meters with the same density and gravitational field strength?

  The pressure is 882,000 pascals.
• How do you calculate the change in pressure when moving from 20 meters to 90 meters depth?

  The change in pressure is 686,000 pascals.
• What is up thrust in the context of submerged objects?

  Up thrust is the upward force exerted by surrounding water on a submerged object.
• Why does a submerged box experience a larger upward force at the bottom than a downward force at the top?

  Because the bottom of the box is deeper than the top, resulting in greater pressure below.
• What determines whether an object floats or sinks in a liquid?

  It depends on whether the up thrust is greater than or less than the object's weight.
• What happens if the weight of an object is greater than the up thrust?

  The object sinks.
• What happens if the up thrust is greater than the weight of an object?

  The object floats.
• How can you determine if an object will float or sink without calculating up thrust and weight?

  By comparing the density of the object to the density of the liquid.
• What happens to an object that is denser than the liquid it is in?

  The object sinks.
• What happens to an object that is less dense than the liquid it is in?

  The object floats.
• What are the key factors that determine pressure in a liquid?

  • Depth of the liquid
  • Density of the liquid
  • Gravitational field strength
• What is the relationship between density and buoyancy?

  • Objects less dense than the liquid float
  • Objects more dense than the liquid sink