Final answer:
To find the force needed to raise a rod due to water surface tension, multiply the surface tension coefficient (7.3x10² N/m) by twice the length of the rod (7 cm), which equals 1.022 Newtons.
Step-by-step explanation:
To calculate the force needed to raise a rod 7 cm long above the surface tension of water, as given with a value of 7.3x10² N/m, we use the formula for surface tension force, which is F = 2γL. Here, γ (gamma) is the surface tension coefficient and L is the length of the rod. Assuming the force is applied along the entire length of the rod and the rod is perpendicular to the water surface, the calculation would be:
F = 2 x (7.3x10² N/m) x (0.07 m)
F = 2 x 7.3 x 0.07
F = 1.022 N
Therefore, the force required is 1.022 Newtons.