Pressure Flashcards
Why do polar explorers use snow shoes or skis?
There is a larger surface area so the weight is more spread out and they don’t sink into the snow
Pressure is the ________ that acts on each ________ ________ of an object
Force
Square metre
Pressure is sometimes described as the ______________ of force
Concentration
The scientific unit for pressure is the ________
Pascal
A gas exerts pressure when its molecules are in ________ _________
Constant motion
When the gas particles collide with a surface they apply a ______ to it
Force
A denser gas will apply ________ force as there’ll be more particles hitting each _______ ______
Greater
Unit area
Why does atmospheric pressure decrease when there is an increase in height?
The number of air molecules decreases the higher up you go so there is less air pushing down on it than there would be at a lower height
What is density measured in?
Kg/m3
Kilograms per metre cubed
Name two illnesses that can be caused by changes in pressure
Altitude sickness
The Bends
What can be used to measure pressure?
Manometers and Barometers
What are Barometers used for?
Predicting changes in weather
What happens to pressure if you go:
A)Under Water
B)Up a mountain
A)Increases
B)Decreases
The ______ the depth, the greater the pressure
Greater
Find the area when:
Force = 506N Pressure = 0.674 kPa
0.75 m2
Find the force when:
Pressure = 10200 Pa Area = 560 cm2
57120 N
Find the pressure when:
Force = 2N Area = 4 cm2
5000 Pa
Why do gases exert pressure?
Use key scientific vocabulary
The particles move in RANDOM MOTION and COLLIDE with the sides of their container. This puts FORCE and EXERTS PRESSURE
In a fluid, the particles are in constant, _________ motion
Random
When a particle _________ with another object it exerts a force. The combined effect of all the particle collisions causes the __________ on objects in contact with the fluid
Collides
Pressure
Why does heating a fluid increase the pressure?
The particles are moving faster
Why do liquids usually exert greater pressure than gases?
The particles in a liquid are closer together
What provides the upthrust?
The weight of the fluid displaced
The weight and upthrust are unbalanced on floating objects
True or False?
False
The weight and upthrust on floating objects are balanced
How do boats float?
The large volume of water displaced by a boat provides the necessary upthrust
What causes atmospheric pressure?
The weight of the air above us
What is the air pressure at sea level?
1 atmosphere
OR
100 kPa
Why aren’t we crushed by air pressure?
The air pressure inside our bodies matched the air pressure outside our bodies
