Một trụrỗng có khối lượng 50 kg, đường kính 1m, đang quay vớivận tốc800 vòng một phút. Tác dụng vào trụmột lực hãm tiếp tuyến với mặt trụvà vuông góc với trục quay. Sau 2 phút 37 giây, trụdừng lại. Tìm:a –Mômen hãmb –Lực hãm tiếp tuyến

In 1859, charles darwin published the first edition of on the origin of species, which explained his observations of various groups of animals that showed great similarities but minor differences. darwin concluded that if a population of one species separates into two different populations that live in separate locations, then over the course of many generations the different populations can develop into different species. this idea predicted many future biological findings and became the basis of modern biology. darwin’s explanation for why different species exist is best described as a(n) law. theory. inquiry. hypothesis.