Measurement of Forces on a Solid Sphere During Impact with a Free Liquid Surface

When a solid impacts a free liquid surface, air jets form around the point of impact. To measure the impact forces associated with this effect, a solid steel sphere, instrumented with an accelerometer, was dropped from various heights (10-40cm) corresponding to different impact velocities (140-280 cm/s). To control the behavior of the air jets, the ambient air pressure above the liquid surface was varied between 0.1-1.0 atmospheres. High speed video images of impact are compared to acceleration profile measurements, thereby permitting quantitative connection of the air jet dynamics to the forces exerted on the sphere during impact.