The

Deformation :
change in
shape or Hooke 's law
size
of an
object .

The
force applied body on a is
twist to its
stretch
, compress ,
directly proportional
within the limit
extension ,
of
shear ,
bending , buckling proportionality .

{ { n' §
A
Force :
push or a
pull Rate of original L
momentum
change of .
length
CLASSMATE
" ' ° ' ' ' '

Physics by Kashan Rashid I

' ' ' '

j
The length f-
in
of
YOUR PARTNER FOR PURSUING EXCELLENCE
Extension :
change ✗ K
" °
F kx 11¥
body
=
a

If Li K constant HE
R= - where :
spring ✓

extension initial
final
-
-

✓
length FIN Hcm F and
length 4cm
10 0 the
x increase
0
by same
•

if x=+ ( extension ) Lf > Li 5 12 2

proportion .

if ✗ ( compression ) 4- Ili 10 14 4
• = -

15 16 6

20 18 8
 constant 1k ) is the " Hm 2
spring measure 1
^

t
of
the
stiffness of the wire
/ spring .

¥
1

K F- force applied
" '
F- Kx ← Ka ' '
:
so
-

-
-

=
✗ ← extension f- iii. iii. •
=
produced =
.
I 24 11 11 '
:

/cm
Eg &
Nkm
ka -10N
-

143--50 o = I 0
=
>
Ok , Kz ¥1m 0
f- FIN
A B
spring spring
CLASSMATE As Fxx
Physicsso ,
line
straightRashid
by Kashan graph passing
lsoft spring ) Chard spring )
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through the origin .

•
ka -10N / cm means 10N
force is needed spring 1 is harder ( greater value
of
K )
-

for 1cm
of extension than
spring 2 .

I
spring 2 stretches more
for the same

KB -50N / cm force needed 11

means 50N is
force than
Spring
• -

extension
for tan
of to
find The value
of K , pick any
The the and
value
of K
depends on co-ordinate
from graph
design and material
of spring .

apply F=kx .
 " "

FIN The
for finding K Elastic limit
point till which
object
:
. . .

^
back the
returns to original if
first find x
applied force is removed .

✗ = ( Li
1¥ f
-

' 1 1 11 11 1 11 , •

If body stretched elastic

=
.

then
a is
beyond
=
apply F- Kx
-
limit
,
it undergoes permanent
does not
deformation and return
0 :
" >
0
* If 4m back to original length .

Hilt llength of wire ) FIN FIN

initial original CLASSMATE Physics by Kashan Rashid "

length
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µeÑ• •

t
year
FIN
n
jiu
^
Iii
•

film ¥1m
'
↳ Limit Elastic limit
of ' xp
proportionality permanent
extension
0
>
0
Hm
Elastic Potential A-
Energy using area =

lzbh
A
-121×111=1
q
( same
Elasticity Ability of
:

body to a
formula )
regain its original shape when EPE Fx and F- ku
deformed 1-2
to
= -

Emma -5=0 =
• Work done on the EPE =

121 Kxtx hence EPE =

tgkxt
=
spring is .
stored as

Imho
E-
F
>
Elastic Potential t

CLASSMATE
'

Example A
Energy .
Physics by spring
Kashan Rashid
: EPE ✗ k

force from 20J

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increased stores
to F when
of energy
extended 5am What
zero by .

FIN stored
^
would be the
energy if the
Fxs
W= same
spring is extended to 8cm .

W=( 0+21=1 ✗
x Area under 1
Assuming limit
'
of pwpor . is not crossed
)
→
F- a EPE ✗ K
graph 52
Work Fx 20×82
1-2
= tells EPE = E ✗

( 5,2
.

2, -

E =
51.2J
EPE =
1- Fx o
>
E -

1812
0
2 24m
 series
springs in
springs in Parallel
- ' " ' "" 111 '
- - - - l - i - i -

§
-

& { & { { { { {
Force Force
③ ① ② ③
All Force
springs experience is
I
I
¥
. •

I
& {
the divided
F
② same
force
.
, F
equally among
I 1--1--1=2--1--3
•

{
F
springs
=

①
.

Fa F} F'
Fg
F,
In
F =
: = =

¥ CLASSMATE Physics by Kashan Rashid

Extension YOUR PARTNER FOR PURSUING EXCELLENCE
Extension
'

Total extension the chain Total extension decreases n' times

their
ofindividual is
by .

sum
of R
,
=Ki=Ns=_ X' =
I
extensions .
n

Xt =
74 +
In -113
it identical springs 1k -
-
same ) xi=xxn
Spring constant
n : no .

of springs spring combination behaves kt=n×k

spring constant as a
stiffer spring .

Spring combination behave Kt =

E.

soft spring
as a .
n
 111

4.

100g 27.2cm
-

V se v 't
200g -

89.7cm v
v
600g
-

Fxx

500g 62.5cm

100g y
27.2+12.5
500 ✗ 100×62.5
y=
39.74m
12.5cm increase
g-
-

5.

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Physics by Kashan Rashid

6.

:|
'

, ,

i i.

0
 112

7.
IN inc .
→ 1cm ext .

PIN
F- KK
p2N
-

f- ✗ K
-

0.5cm ext
0.5N tire → .

0.5N * * 0.5N
IN # MN

0
8.
CLASSMATE 0
Physics by Kashan Rashid
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Ego
0.5L 05L
µ I
F- = KN IF xf
✗

÷=
* L

:
ppl

.
 114
13 The graph shows the extension of a piece of copper wire as the load on it is increased.

extension
of wire

0
0 load

What does the graph show?

A At a certain load, the wire becomes easier to extend.

B At a certain load, the wire becomes harder to extend.
C The load and the extension are directly proportional for all loads.
D The load and the extension are inversely proportional for all loads.

14 The graph shows extension-load curves for four fibres.

Which fibre is the most difficult to stretch over the range of loads shown?

extension A
B
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C by Kashan Rashid
Physics

0
0 load

15

→ → → →
 117

• •

3cm
4cm

For the B
same
force e.
g.
15N ,
spring stretches more

i. e. 4cm than A i. e- 3cm

spring
CLASSMATE Physics by Kashan Rashid
.

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Graph of spring B curves

after 25N but
graph
of Spring straight
A is still a line .

15N
 121

4.

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Physics by Kashan Rashid
 122

CLASSMATE
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Physics by Kashan Rashid
 131

CLASSMATE
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Physics by Kashan Rashid
 132

CLASSMATE
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Physics by Kashan Rashid