kiểm tra bền của dầm tổ hợp sau: dầm đơn giản nhịp L=10m chịu tổng tải trọng phân bố đều tiêu chuẩn qtc=45kN/m, hệ số độ tin cậy của trọng tải bằng 1.15. Dầm có tiết diện chữ I ghép từ 3 bản thép kích thước mỗi bản là -300x16mm và bản bụng là -1000x8mm. Dầm làm bằng thép CCT34, hệ số điều kiện làm việc bằng 1. Hàn tay, que hàn N46

The motor m applies a time-varying force of f (200 t) n, where t is in seconds. box b with mass 200 kg starts from rest, and the coefficients of kinetic and static friction are 0.2 and us 0.3 the acceleration due to gravity is g 9.8 m/s2 b 300 a) find the time ' when the box starts to move. b) calculate the speed of the crate at 3 s c) calculate the power delivered by the motor at t 3 s

If a balloon is taken outside on a very cold day, what will occur?

Arunner is jogging at a steady 3.6 km/hr. when the runner is 2.9 km from the finish line, a bird begins flying from the runner to the finish line at 14.4 km/hr (4 times as fast as the runner). when the bird reaches the finish line, it turns around and flies back to the runner. even though the bird is a dodo, we will assume that it occupies only one point in space, i.e., a zero-length bird. how far does the bird travel? (b) after this first encounter, the bird then turns around and flies from the runner back to the finish line, turns around again and flies back to the runner. the bird repeats the back and forth trips until the runner reaches the finish line. how far does the bird travel from the beginning? (i.e. include the distance traveled to the first encounter)