P5 Flashcards
define a scalar
only has magnitude
define a vector
has magnitude and director
e.g. for an arrow -> length = magnitude
direction = direction
vector quantities
force velocity displacement acceleration momentum
scalar quantities
speed distance mass temperature time
define a force
push or pull that acts on an object due to the interaction with another object
contact OR non-contact
what needs to be the case for a contact force to act?
objects are physically touching
what needs to be the case for a non-contact force to act?
objects are physically separated/not touching
examples of contact forces
friction
air resistance
tension
normal contact force
examples of non-contact forces
gravitational force
electrostatic force
magnetic force
what happens when 2 objects interact/interaction pair?
when 2 objects interact a force is produced on both
interaction pair -> pair of equal and opposite forces acting on 2 interacting objects
define weight
the force acting on an object due to gravity
newtons (N) -> newton meter
(changes with location)
define mass
amount of matter in an object
kg -> mass balance
what does the weight of an object depend on?
the gravitational field strength at the point where the object is (GFS = stronger when your closer to the mass causing the field and stronger for large masses)
state the relationship between mass + weight
direct proportion
GFS of earth?
9.8 N/kg
weight equation?
weight (N) = mass (kg) x GFS (N/kg)
define centre of mass
weight of an object conc. at a point
equal in all directions
define resultant force
overall force acting on an object/point
in one direction
what’s the RF if the forces are balanced?
0
how is work done by a force/energy treansferred?
the force (RF) causes an object to move though a dist. (displacement)
work done equation?
work done = force x dist.
unit of work done?
joules (J)
unit of dist.
metres (m)
relationship between joules and newton-metres?
1 joule = 1 newton-metre
what does work done against frictional forces cause?
rise in temp. of the object
explain how work is done when you push something along a rough surface
work is done against frictional forces
energy transferred to KE store of object as it moves
some energy transferred to object’s thermal stores -> friction
causes overall temp. of object to increase
what does it mean if an object is in equilibrium?
all forces acting on the object combine to give an RF of 0
CHECK pg.54
what 3 things ca happen when more than 1 force is applied to an object?
object: bends, stretches or compresses
define elastically deformed
can go back to its original shape/length after the force is removed
what is an elastic object?
can be elastically deformed
define inelastically deformed
doesn’t go back to its original shape/length after the force is removed
what happens when a force stretches/compresses an object?
when elastically deformed?
work is done
energy transferred to elastic potential energy store of object
if elastically deformed, all energy transferred to EPE
relationship between extension and force?
direct proportion
force and extension equation?
force = k (spring constant) x e (extension)
when does the direct proportion between force + extension stop?
when the force is too great and limit of proportionality is exceed
