applications of forces Flashcards
natural length
this is the normal length of the spring without a load on it
extended length
this is the length of the spring when it is loaded
extension
this is the difference between the extended length and the natural length
extension=_____________________
extended length - natural length
Hooke’s law
Hooke’s law states that the extension of a spring is directly proportional to the applied force, provided the limit of proportionality has not been reached
elastic behaviour
when the load is removed the spring will return to its original size and shape
force =
(Springs)
f=ke
/__F__\
/K|E\
equation for pressure
p=f/a
/__F__\
/P|A\
units for pressure
Pascals (Pa)
pascals can only be used if _________________
we have an area in m2
pressure is directly proportional to ________
force
pressure is inversely to __________
area
practical uses of pressure
-small SA on blade of a knife: large pressure
-blade of an ice skate
-heel of a stiletto
-small pressure from digger wheels
-snow shoes: large sa so small pressure
-large area of house foundations: small pressure
centre of gravity
the centre of gravity of an object is the point where all of the weight of the object can be considered as acting
when an object is supported at or under its centre of gravity it will _______
balance
a lever is a _________________________
force multiplier
pivot
the pivot is the point on which something turns
the turning effect of a force is called ________________________
the moment force
the moment of a force depends on the
- size of the force
- the distance the force if from the pivot
moment of force=
moment of force= force x perpendicular distance from the pivot
/__M__\
/_F__|D\
principle of moments
for an object to be balanced the sum of the clockwise moments about a point must equal to the sum of the anti-clockwise moments about that point
you can increase the stability of an object by:
- lowering its centre of gravity
- increasing the width of its base
stability
the position of the centre of mass of an object determines whether it will topple over easily or not
equilibrium
a body is in a equilibrium when both the resultant force and the resultant turning effect on it are zero
3 types of equilibrium
- neutral equilibrium
- unstable equilibrium
- stable equilibrium
