Form 4 Term 1 Physics Unit 17 Mechanics 2 Flashcards
Acceleration
The rate of change in speed is measured in metres per second squared
Deceleration
Slowing down or negative acceleration
Displacement
Quantity describing the distance from from start of journey to end of journey in a straight line with a direction
Example 50km due north of starting point
Force
Is a push or a pull
Unit of force is the NEWTON N
Magnitude
The magnitude tells us the size of the vector
Moment
A turning force around a pivot - clockwise or counterclockwise
Measure in Newton-metres Nm3 (force and distance)
Force multiplied by the perpendicular distance to a pivot
Stationary
Not moving
Velocity
The speed an object moves in a particular direction
Gravity
The force of attraction between all objects
More mass in an object means the it exerts a larger force of gravity
More mass = exerts more force of gravity
Inversely
Two variables are inversely related if one decreases when the other increases
Mass
Mass is measured in kilograms KGS
mass of an object is a measure of unwillingness of an object to change its velocity (to accelerate)
Large rock = more mass = hard to make it move quickly / gain velocity
Matter
Sub atomic particles
Oppose
When one things works against something else to reduce of eliminate effect
Example: an opposing force to a PUSH is a PULL
Frictional force
Force that resists one object moving through or over something
Example: air resistance on a car as it drives along (like when hold hand out car window)
Kinetic energy
Energy which an object possesses by being in motion
Resultant force
The single force that could replace all the other forces acting on an object
Calculated by adding all forces together.
If all forces are equal the resultant force is zero
Surface area
The total area of an object
Terminal velocity
The max speed of an object - reached when the forces moving on the object are balanced by its frictional forces.
At terminal velocity acceleration is zero (it can’t go any faster it’s at maximum)
Pressure
The force per unit
Measured in Pascals PA
What does pressure determine ?
The effect of a force on a surface
Measures in Pascals - Pa
What happens to acceleration at terminal velocity
It is at zero - the object has reached its maximum Speed
What unit is pressure measured in and what is the symbol
Pascal
Pa
What unit is force measured in and what is the symbol
newtons
N
What unit is area measured in and what is the symbol
Metres squares
m2
What does pressure help to do ?
Helps to move blood around the body
Allows organisms to breathe
What does bigger surface area mean for pressure
Means less presssure when greater surface area
Normal Shoes on snow have lots pressure so sink into snow
Snowshoes have big surface area so they reduce the pressure you exert on the snow so you don’t sink
what did robert boyle discover
that volume is inversely proportional to pressure (more pressure equals less volume)
he trapped a bubble of an air in a J shaped tube which was caped at one end. poured mercury in and slowly increased the pressure and the air bible got smaller
more pressure causes less volume eg squeeze balloon
what is the pressure in the atmosphere at sea level
100,000 Pascals (Pa)
what did greek scientist archemide discover
the physical law of buoyancy
what is the Archimedes Can/Eureka can theory?
any object immersed in a fluid is acted upon by an upward, or buoyant, force equal to the weight of the fluid displaced by the object.
When an object is dropped into water it will float because of the upward or buoyant force on it
pressure and gases
the pressure is created by the molecules colliding - the faster they collide the pore pressure and they push outwards
if you contain a gas in a confined spaced what happens to pressure
it increases as there are more collisions - a balloon expands outwards
what is the difference between velocity and speed
velocity is speed in a direction
what happens to atmospheric pressure as you go higher
in increases because as altitude increases
- the number of air molecules decrees
- the weight of the air decreases
- less air above the surface
what is the relationship between pressure and volume
more pressure means less volume eg squeeze a balloon
what is density
how closely packed particles are in a solid liquid or gas
how do you calculate density
mass divided by volume
do heavier items have more or less density
more as the particles re more closely packed in the same volume
what is the unit for density
kg/m3 or g/gm3
is water or ice more dense ?
about the same as same number of particles the space it takes up. ice cube and water take same space.
When turn water to steam it has less density as particles get further apart
forces are usually
a push or pull
force is measure in what unit
Newtons
what is turning force and what unit is it measured it
a Moment - measure in Newton metres (force and distance)
when you draw graphs to show speed/distance etc what 4 things must you include
units
line or curve
points
labels
on velocity time graph how would you find displacement
o the areas under the line
Newtons main law of motion
every action has an equal and opposite reaction
that means - forces act in pairs
