6.
a)
Step 1: Understand the Force-Extension graph for a single spring.
For a spring obeying Hooke's law, the force (F) is directly proportional to the extension (e), so the graph of Force vs. Extension is a straight line passing through the origin, with a positive slope.
Step 2: Consider two identical springs connected end to end (in series).
When two identical springs are connected in series, the total extension for a given force is the sum of the extensions of each spring. If a force F causes an extension e in one spring, then the same force F will cause an extension of e in each of the two springs in series, resulting in a total extension of 2e.
This means that for the same force, the total extension is doubled. Therefore, the effective spring constant of the series combination is half that of a single spring (kseries=k/2).
Step 3: Sketch the graph.
The new graph for two springs in series will also be a straight line passing through the origin. However, its slope will be half the slope of the graph for a single spring, indicating that it is less steep.
\begin{tikzpicture}
\begin{axis}[
xlabel={Extension},
ylabel={Force (N)},
xmin=0, xmax=5,
ymin=0, ymax=10,
axis lines=middle,
xtick=\empty, ytick=\empty,
clip=false
]
\addplot[thick, blue, domain=0:4] {2*x}; % Original spring (steeper)
\node[above right, blue] at (axis cs: 3, 6) {Single spring};
\addplot[thick, red, domain=0:4] {x}; % Two springs in series (less steep)
\node[above right, red] at (axis cs: 3, 3) {Two springs in series};
\end{axis}
\end{tikzpicture}
(Description of sketch: Draw a graph with "Extension" on the x-axis and "Force (N)" on the y-axis. Draw two straight lines starting from the origin. The first line (representing a single spring) should have a steeper positive slope. The second line (representing two springs connected end to end) should have a less steep positive slope, approximately half the slope of the first line.)
b) Determine the extension of the system.
Step 1: Determine the extension of a single spring under a given force.
Given that each spring extends by 2 cm when a force of 50 N is suspended from it.
So, for one spring: F0=50N⟹e0=2 cm.
Step 2: Analyze the series combination of springs C and D.
The 50 N load is suspended from spring D, which is suspended from spring C. In a series connection, the force acting on each spring is the same as the total load.
Force on spring C (FC) = 50 N.
Force on spring D (FD) = 50 N.
Extension of spring C (eC) = 2 cm (since it's an identical spring under 50 N).
Extension of spring D (eD) = 2 cm (since it's an identical spring under 50 N).
The total extension of the series combination (C and D) is the sum of their individual extensions:
eCD=eC+eD=2cm+2cm=4 cm
Step 3: Analyze the parallel combination of springs A and B.
The horizontal bar supports the combination of C and D, which carries the 50 N load. Therefore, the total force acting downwards on the horizontal bar is 50 N.
This force is distributed equally between springs A and B because they are identical and connected in parallel.
Force on spring A (FA) = 250N=25 N.
Force on spring B (FB) = 250N=25 N.
Now, calculate the extension of spring A (or B) under a force of 25 N. Since extension is proportional to force: