题目

阅读理解 Deciding to get her money's worth out of thewedding dress on which she spent over $1,000, an Australian woman has beenwearing her wedding dress, a year after her wedding. 43-year-old Tammy Hall adopted a newlifestyle-anti-consumerism (反消费主义) lifestyle in 2016, aftera trip to India opened her eyes to how much we as a society consumed. Shedecided not to buy any new clothes or footwear for a whole year after shereturned home to Adelaide, in Southern Australia, and she managed to make it. But last year, as her wedding day approached,she faced a dilemma. She wanted to look go在一“抗洪救险”中，一名受灾群众找到一张总体积为0.3m3的长方体塑料泡沫床垫来自救．将其放入水中时，床垫有1/5体积浸没在水中（g取10N/kg），求：（1）此时床垫受到的浮力是多大？（2）此塑料泡沫床垫的密度是多少？