Chapter 3: Motion and Pressure Flashcards
(22 cards)
What is speed?
How far something moves in a certain time
What is the equation for speed?
Speed (m/s) = Distance travelled (m)/ Time taken (s)
What is speed measured in?
Metres per second (m/s)
What is relative motion?
How fast one object is moving compared to another
What is two objects relative speed if they are moving at the same speed in the same direction?
Zero
What is pressure?
The force exerted on a surface because of weight
What is force measured in?
Newtons per metre squared
What is the equation for pressure?
(N/cm^) = Force (N)/ Area (m^)
What do collisions between gas molecules and their containers produce?
Gas pressure
How do you get a higher pressure?
By compressing a gas into a smaller volume
What happens if you heat a gas?
The particles will have more energy, this means they will move more quickly and collide with the container more often
What is atmospheric pressure?
The pressure acting on us from air around us
What happens to the atmospheric pressure as you go higher?
It gets lower as the air is less dense the higher you go, so there are fewer collisions between air particles
Why are solids and liquids imcompressible?
As all the particles are already touching, meaning they pass pressure on
Why does pressure increase with depth?
The pressure at the bottom of a liquid is bigger than the top, because of the weight of the water
What are moments?
The turning effect of a force
What is the unit for the moment?
Newton metres (Nm)
What is the equation for the moment?
Moment (Nm) = Force (N) x Perpendicular distance from the pivot (m)
How does the moment get bigger?
The bigger the force, or the further the distance
What must happen during equilibrium?
The clockwise moments added together must equal all of the anticlockwise moments added together
Why do objects float?
Upthrust
What is upthrust?
Liquid pressure produces upthrust, objects float because the upthrust acting on the bottom of it is stronger than the forces acting on the top
