HYD201: Bài tập Thủy tĩnh học

• Đăng bởi: nguyenphuocbinh
• Sinh viên
• 17/12/2016

Problems
1. Shoes are to be designed to enable people of up to 80 kg to walk on freshwater or seawater. The shoes are to be made of blown plastic in the shape of a sphere, a (American) football, or a loaf of French bread. Determine the equivalent diameter of each shoe and comment on the proposed shapes from the stability point of view. What is your assessment of the marketability of these shoes?

2. The volume of a rock is to be determined without using any volume measurement devices. Explain how you would do this with a waterproof spring scale.

3. The density of stainless steel is about 8000 kg/m3 (eight times denser than water), but a razor blade can float on water, even with some added weights. The water is at 200C. The blade shown in the photograph is 4.3 cm long and 2.2 cm wide. For simplicity, the center cut-out area of the razor blade has been taped so that only the outer edges of the blade contribute to surface tension effects. Because the razor blade has sharp corners, the contact angle is not relevant. Rather, the limiting case is when the water contacts the blade vertically as sketched (effective contact angle along the edge of the blade is 1800). (a) Considering surface tension alone, estimate (in grams) how much total mass (razor blade + weights placed on top of it) can be supported. (b) Refine your analysis by considering that the razor blade pushes the water down, and thus hydrostatic pressure effects are also present.