Bài 1. Một chiếc ca nô sang ngang một dòng sông có nước chảy với vận tốc v1 = 1,2 m/s. Muốn cho ca nô chuyển động vuông góc với bờ sông với vận tốc v12 = 3,2 m/s thì động cơ của ca nô phải tạo cho nó một vận tốc bằng bao nhiêu?

3. a worker pushes a 30.5 kg polished stone along a polished table with a force on bonin a straight line for 5.20 s after starting from rest. there is no friction between thestone and the table. at the end of the table. the stone is hooked to a cable with a lengthof 62.0 cm to rotate it to a rough table to store until they can be picked up. the roughtable has a coefficient of static friction 0.702 with the polished stone. remember that 8= 9.80 m/s2a) what is the speed of the stone when it is hooked to the cable? b) what is the tension in the cable while the stone is rotating? (there is still nofriction)c) how much force is needed to make the stone begin sliding from rest on therough table? ius = 0.70262.0 cm30.5 kg20.5 kg6= 0