The Resistive Force on a Sphere with a String Moving in a Viscous Fluid

Shan-Tarng Chen

Chinese Journal of Physics

32卷4期（1994 / 08 / 01）

395 - 404

英文

The viscous drag force acting on a steel sphere fastened with a thin cotton string moving through glycerin has been determined using a photogate apparatus. The positions Y(t) of three spheres of different sizes used in the experiment versus time t were measured and compared. Experimental terminal velocities for different string lengths L were found to agree satisfactorially with theoretical values. Via comparative studies of the data for the three spheres, the viscous force due to the string alone for the lightest sphere was determined to be fL = cLηV, where η and V are respectively the viscosity coefficient of the resistive fluid and terminal velocity of the sphere with the string and c = 1.278 ± 0.042 numerically.