P11 Force and pressure Flashcards
What is the formula for pressure?
Pressure(pascals)=force(newtons)/area(m^3)
How does pressure change with liquids?
Pressure increases with depth but until the pressure along the same horizontal line is constant, the liquid will flow. The greater the density, the greater the pressure. p=hpg
What is atmospheric pressure?
It is due to air molecules colliding with surfaces where each impact releases a tiny force on the surface but as there are so many that collide it is large.
How does pressure change in the atmosphere?
The density of the atmosphere decreases with increasing height above the ground. This is because the weight of air pressing down on a horizontal surface at any altitude decreases with altitude.
What is the equation for pressure at sea level?
Pressure=height x density x gravity
What is upthrust?
It is where water exerts an upward force on a body.
How can upthrust be explained?
It is due to the object displacing water. The more of the object lowered into the water, the bigger the volume of water displaced, the greater the upthrust. When the object is fully immersed, the volume of the water displaced is equal to the volume of the object.
What determines if an object will float or sink?
An object floats when its weight is equal to the upthrust and sinks when the weight is greater than the upthrust.
How to determine if an object will float or sink in water?
If the object is more dense than water it will sink as the weight is greater but if it is not denser than water it will float.
