Central Stand Exhibits KL05 Bowling ball cannon


Can you make the tennis ball reach the ceiling?

Make the bowling ball drop in the tube by pulling on the cord.
Observe the tennis ball in the other tube.

The bowling ball forces the air column in the larger tube to move, thereby blasting the tennis ball in the smaller tube up toward the ceiling with high speed.

An equal amount of gas is flowing through each cross-section of the tube within any given time. The bowling ball in the larger tube acts like a piston, forcing the air column in the tube to move. When the air column is forced into the other tube with a smaller diameter, its speed will increase. This is because, as stated by the law of conservation of mass, the mass remains unchanged within a closed system. As a result, the same amount of gas in the same time moves through the narrow tube at a faster rate than in the wider tube.

The human vascular system is a closed system in which blood flows as a result of the heart’s pumping. As the heart contracts, it sends a pressure wave through a major blood vessel, the aorta. The speed of the pressure wave depends on the resilience of the arteries. The blood flow is slowed by, for example, the resistance of flow caused by vascular friction and stenoses. When a stenosis is formed in a blood vessel, the cross-sectional area of the vessel decreases, in other words, the vessel narrows, and the speed of flow of the blood increases locally at that site.

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