Topic
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Displacement
Vectors
Kinematics
Graphs
Energy
Power
Springs
Shadows
Field of Vision
Colors
Concave mirrors
Convex mirrors
Refraction
Lenses
Optical Power
Slides Minutes
9
27
13
39
13
39
10
30
10
30
5
15
4
12
3
9
7
21
3
9
7
21
4
12
5
15
10
30
6
18
As illustrated below, the distance a spring is stretched is called
the “elongation”. Robert Hooke was the first to discover that the
spring force is directly proportional to the elongation. Today, we
call this law Hooke’s Law.
The formula for the spring is: FS = kx
 (Hooke’s Law)
Where: FS = the spring force (N)
k = the spring constant (N/m)
x = the elongation (m)
Click
When the spring force (FS) is plotted versus the elongation (x) of
the spring, the resulting graph is a linear relation. The slope of
the curve represents the spring constant while the area under
the curve represents the potential energy stored in the spring.
Click
Springs Slide: 7. 1
When the spring force is plotted versus the elongation of the
spring:
a) How do you determine the spring constant (k) from the graph?
By finding the slope of the plotted line.
b) How do you determine the potential energy (EP) stored in a
spring from the graph?
By finding the area under the slope.
Click
Springs Slide: 7. 2
The graph on the right represents the
force-compression graph of an ideal spring.
Determine the spring constant.
Click
Springs Slide: 7. 3
Jim wants to compress a coil whose spring constant is 120 N/m.
To do so, he uses a lever attached in such a way that the
actual mechanical advantage (AMA) is 3 as illustrated below.
How much force must Jim apply in order to compress the spring
a distance of 50 cm?
Note that the resistance force = the spring force
Click
Springs Slide: 7. 4
The graph on the right was obtained by
applying various weights to a spring.
The spring is then attached to a 5.0 kg
cart and stretched 0.40 m by an applied
force of 25 N (as illustrated).
Note that to find the spring constant,
0.40 m
Determine the frictional force between
we need to invert the slope from the
the surface and the cart as the cart
given graph because k = F/x. FA = 25
was stretched.
N
5.0 kg
Step-1 Find the spring constant (k)
Step-3 Find the frictional force (f)
Step-2 Calculate the spring force
Given
Click
Springs Slide: 7. 1
… and good luck!