forces, movement & changing shape Flashcards
what is a force
push or pull that arises from the interaction between objects
what are the 2 different types of forces
gravitational force
reaction force
what is a reaction force
When an object rests on a surface, the surface exerts a push force on the object
This reaction force acts at right angles (perpendicular) to the surface
what is gravitational force
There is a gravitational force of attraction between all objects with mass
The more massive the object, the greater the gravitational force exerted by it
thrust
a force produced by an engine that speeds up the motion of an object
upthrust
When an object is fully or partially submerged in a fluid, the fluid exerts an upward-acting push force on the object
air resistance
Air resistance occurs when particles of air collide with an object moving through it and slows its motion
drag force
a type of frictional force that occurs when an object moves through a fluid (a gas or a liquid)
The particles in the fluid collide with the object moving through it and slow its motion
friction
frictional forces always oppose the motion of an object, causing it to slow down
Friction occurs when two surfaces move over one another
magnetic force
There is a magnetic force between objects with magnetic poles
Like poles repel one another, opposite poles attract one another
tension
Tension occurs in an object (like a rope or spring) that is stretched
When a pull force is exerted on each end of an object, tension acts across the length of the object
When a force acts on an object, there are 3 effects
change speed
change direction
change shape
scalar
have magnitude
vectors
have magnitudes and not direction
example of scalar
mass
example of vector
weight, forces
what is a resultant force
a single force that describes all of the forces operating on a body
resultant force determines
The direction in which the object will move as a result of all of the forces
The magnitude of the net force experienced by the object
friction
A force which opposes the motion of an object
when forces are balanced, the resultant force will be
zero
stopping distance is
the total distance travelled during the time it takes to stop in an emergency
to calculate stopping distance,
Thinking distance + Braking distance
thinking distance
the distance travelled in the time it takes the driver to react to an emergency and prepare to stop
factors affecting thinking distance
speed of car
reaction time of driver
reaction time
A measure of how much time passes between seeing something and reacting to it
factors affecting reaction distance
Tiredness
Distractions (e.g. using a mobile phone)
Intoxication (i.e. consumption of alcohol or drugs)
breaking distance
the distance travelled under the braking force in metres (m)
factors affecting stopping distance
speed
mass
road condition
reaction time
terminal velocity
he fastest speed that an object can reach when falling
when is terminal velocity reached
when the upward and downward acting forces are balanced / when the resultant force acting on the object reaches 0
falling objects experience two forces:
weight
air resistance
as object falling speed increases, what happens to air resistance
increases
why does air resistance increase as speed does in a falling object
because the object collides with air particles as it moves through the air
The faster the object is travelling, the more collisions it has with the air particles
