upthrust and atmospheric pressure

• what is upthrust?

  when an object is submerged in a fluid the pressure of the fluid exerts a force on it from every direction

  pressure increases with depth so the force exerted at the bottom is larger which is the resultant force upthrust
• upthrust is equal to the weight of the fluid that has been displaced by the object
• the object floats if the weight is equal to the upthrust causing a balance
• if the weight is greater than the upthrust then the object sinks
• the object that is less dense than the fluid will displace a volume of fluid that is equal to its weight
• atmospheric pressure is created is created on the surface by air molecules colliding
• as the altitude increases the atmospheric pressure decreases because the atmosphere becomes less dense so there is fewer air particles to collide with the surface