AS Mechanics Flashcards
What is a particle?
a body whose dimensions, except for mass are negligible
Where is the mass concentrated in a particle
concentrated at a single point
Which forces can be ignored when regarding a particle?
Rotational forces
Air resistance
What is a bead?
A particle with a hole in it for threading on a wire or a string
Where is tension on a bead?
Tension is the same either side
What is a wire?
Rigid thin strip of metal
What modelling assumption is made about wires?
Treated as one dimensional
What is a rod?
An object whose mass is concentrated along a line
All dimensions but one are negligible
What is meant by the term negligible?
small enough that it can be ignored
What is a uniform rod?
One which equal lengths have equal masses - means that the weight can be taken from the centre
What is a light object?
One whose mass in negligible
What is a lamina?
A flat body having area but negligible thickness
What is a uniform lamina?
One which equal areas of lamina have equal masses
What is a peg?
A pin from which a body can be suspended or rested
Is a peg dimensionless?
yes
Difference between a smooth and rough peg
Smooth peg has no friction
Rough peg would have a frictional force
What is an inextensible/inelastic string and what does this mean for particles attached?
one that doesnt stretch and length never changes
Acceleration is the same for all particles attached to a taut string
What is meant by a smooth surface?
One which offers no resistance to motion eg no friction
What is meant by a rough surface?
One where friction has to be taken into account
What is a smooth pulley and what does this mean for tension?
One with no friction in its bearings - tension in the string will be equal on the two sides of the pulley
What is a plane surface?
A completely flat surface
What is weight?
force acting on an object due to gravity
What is resistance?
any force that opposes the motion of an object
What is friction?
type of resistance force caused when objects are trying to slide against one another
What is reaction force ?
when two objects are in contact, each exert a reaction force on the other
What is the direction of a reaction force?
perpendicular to the surface on contact
What is a driving force?
force applied to an abject to cause it to move
What is braking force?
force applied to a moving object with the intention of slowing it down
What is tension?
force produced by an object that prevents it being stretched
What is thrust / compression?
force produced by an object that prevents it being squashed
What is lift?
an upwards force that acts on an aircraft enabling it to take off
What is buoyancy?
an upwards force acting on an object floating on water that stops it from sinking
