applications of forces

Question 1

natural length

Answer 1

this is the normal length of the spring without a load on it

Question 2

extended length

Answer 2

this is the length of the spring when it is loaded

Question 3

extension

Answer 3

this is the difference between the extended length and the natural length

Question 4

extension=_____________________

Answer 4

extended length - natural length

Question 5

Hooke’s law

Answer 5

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

Question 6

elastic behaviour

Answer 6

when the load is removed the spring will return to its original size and shape

Question 7

force =
(Springs)

Answer 7

f=ke

/__F__\
/K|E\

Question 8

equation for pressure

Answer 8

p=f/a

/__F__\
/P|A\

Question 9

units for pressure

Answer 9

Pascals (Pa)

Question 10

pascals can only be used if _________________

Answer 10

we have an area in m2

Question 11

pressure is directly proportional to ________

Answer 11

force

Question 12

pressure is inversely to __________

Answer 12

area

Question 13

practical uses of pressure

Answer 13

-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

Question 14

centre of gravity

Answer 14

the centre of gravity of an object is the point where all of the weight of the object can be considered as acting

Question 15

when an object is supported at or under its centre of gravity it will _______

Answer 15

balance

Question 16

a lever is a _________________________

Answer 16

force multiplier

Question 17

pivot

Answer 17

the pivot is the point on which something turns

Question 18

the turning effect of a force is called ________________________

Answer 18

the moment force

Question 19

the moment of a force depends on the

Answer 19

1. size of the force
2. the distance the force if from the pivot

Question 20

moment of force=

Answer 20

moment of force= force x perpendicular distance from the pivot

/__M__\
/_F__|D\

Question 21

principle of moments

Answer 21

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

Question 22

you can increase the stability of an object by:

Answer 22

1. lowering its centre of gravity
2. increasing the width of its base

Question 23

stability

Answer 23

the position of the centre of mass of an object determines whether it will topple over easily or not

Question 24

equilibrium

Answer 24

a body is in a equilibrium when both the resultant force and the resultant turning effect on it are zero

Question 25

3 types of equilibrium

Answer 25

1. neutral equilibrium 2. unstable equilibrium 3. stable equilibrium