sp15 - upthrust and atmospheric pressure Flashcards
pressure increases with depth so…
the force exerted on the bottom of the object is larger than the force acting on top of the object
what is upthrust equal to
the upthrust is equal to the weight of fluid that has been displaced by the object
what does it mean when an object floats
if the upthrust on an object is equal to the object’s weight, then the forces balance and the object floats
what does it mean when an object sinks
if an object’s weight is more than the upthrust, the object sinks
what happens when an object is less dense than the fluid it is placed in
an object that is less dense than the fluid it is placed in displaces a volume of liquid that is equal to the upthrust, so the object floats
what happens when an object is more dense than the fluid it is placed in
an object that is denser than the fluid it is placed in is unable to displace enough fluid to equal its weight. This means that its weight is always larger than the upthrust so it sinks
how is atmospheric pressure created
atmospheric pressure is created on a surface by air molecules colliding with the surface
what happens to the atmosphere as the altitude increases
the atmosphere gets less dense, so fewer air molecules can collide with the surface
what happens to the pressure when an object is submerged in a fluid
when an object is submerged in a fluid, the pressure of the fluid exerts a force on it from every direction
