P11 - Pressure✔️

Question 1

Equation for pressure (p) ?

Answer 1

Pressure (p) = force (F) / area (A)

Question 2

Unit for pressure?

Answer 2

Pascals (Pa) - which is equal to one newton per sqaure metre (N/m^2)

Question 3

Define pressure?

Answer 3

Pressure is caused when objects exert forces on each other, or when a fluid (can be a liquid or gas) exerts a force on an object in contact with the fluid

Question 4

Equation for caculaing the pressure due to a coloum of liquid?

Answer 4

pressure = height of the column × density of the liquid × gravitational field strength

Question 5

Explain upthrust?

Answer 5

Partialy or totally submerged objects expirences a greater pressure on the bottom surface than on the top surface - this creates a resulant force upwards - this force is called upthrust

Question 6

Why does pressure of a liquid increase at greater depth?

Answer 6

Pressure increases as the depth increases. The pressure in a liquid is due to the weight of the column of water above. Since the particles in a liquid are tightly packed, this pressure acts in all directions

Question 7

How is atmospheric pressure created?

Answer 7

Air molecules coliding with a surface creates atmospheric pressure

Question 8

Why does the density of the atmosphere decrease with increasing height above the ground(increasing altitude)?

Answer 8

The weight of air pressing down on a horizontal surface at any altitude decreases with altitude - so there are fewer molecules per cubic metre and therefore fewer impacts per second at a higher altitude so atmospheric pressure decreases - at increased altitude,there is less weight of air above

Question 9

When an object is fully immersed the volume of water displaced is equal to ….?

Answer 9

The volume of the object

Question 10

Explain how a boat carrying a heavy load will not sink?

Answer 10

A ship displaces more water when the load increases, so the upthrust increases - the upthrust is equal to the weight of the ship and its cargo however if it is loaded with too much, it sinks because it has displaced as much water as it possiby can and because the uphthrust can no longer support the total weight

Question 11

Explain why materials like wood or cork float in water but metal sinks?

Answer 11

Objects that sink have a density greater than the density of water