Question 4: Determine the weight of the object. Question 5: Determine which submarine experienced the highest change in pressure.

The unstretched length of the spring is 15.0 cm.
The length of the spring with the object suspended is 16.4 cm.

From the graph, an extension of 1 cm corresponds to a load of 1 N. The graph shows a linear relationship where extension (cm) is equal to load (N).
Therefore, for an extension of 1.4 cm, the load (weight) is 1.4 N.
The final answer is $\boxed{1.4 \text{ N}}$.

The change in pressure ($\Delta P$) in a fluid is directly proportional to the change in depth ($\Delta h$), given by the formula $\Delta P = \rho g \Delta h$, where $\rho$ is the fluid density and $g$ is the acceleration due to gravity. Since $\rho$ and $g$ are constant, the highest change in pressure corresponds to the highest change in depth.

• Submarine P: Initial depth = 10 m, Final depth = 30 m.

• Submarine Q: Initial depth = 50 m, Final depth = 70 m.

• Submarine R: Initial depth = 10 m, Final depth = 70 m.

• Submarine S: Initial depth = 30 m, Final depth = 50 m.

Submarine R has the largest change in depth (60 m).
Therefore, submarine R experienced the highest change in pressure.
The final answer is $\boxed{\text{Submarine R}}$.

The length of the string is 2.2 cm.
The string is wound 5 times around the pen.

When the string is wound 5 times around the pen, its total length is 5 times the circumference of the pen.

The formula for the circumference of a circle is $C = 2\pi r$, where $r$ is the radius.

Using $\pi \approx 3.142$:

The final answer is $\boxed{0.070 \text{ cm}}$.