It is difficult to detect the specific gravity of plastic pepper balls, because the specific gravity of plastic pepper balls is affected by the specific gravity of materials, the wall thickness and the diameter specifications of plastic pepper balls. Therefore, the specific testing technology is needed to test the specific gravity of plastic pepper balls.

The specific gravity test method of plastic pepper balls is to use a cylindrical container, a scale and a small plastic bowl. Put the cylindrical container on a horizontal table and fill it with a proper amount of water, so that the plastic bowl floats on the water. At this time, the water depth in the container is 18cm. When the hollow plastic ball is put into the water in the container, the water depth in the container is 19.5cm, as shown in Figure A.. Now take out the plastic pepper ball and put it in a small plastic bowl to stand still, as shown in figure B. The water surface in Figure B is 3cm higher than that in Figure A.. It is known that the inner bottom area of the container is 400cm2. The density of pepper balls is 0.3kg/m3.