Physics课程试卷(b).docVIP

Physics（B） Department Grade Specialty Number　　　　　　　 Name　　　　　　　Score 一. Fill in the blanks (40) 1. In figure, a block B of mass M=15.0kg hangs by a cord from a knot K of mass Mk, which hangs from a ceiling by means of two other cords. The cords have negligible mass, and the magnitude of the gravitational force on the knot is negligible compared to the gravitational force on the block. What are the tensions in the three cords? , , . 2. Two ships, A and B, leave port at the same time. Ship A travels northwest at 24 knots and ship B travels at 28 knots in a direction 400 west of south. (1 knot=1 nautical mile per hour=1852 meters per hour) (a) The magnitude and direction of the velocity of ship A relative B are , ;(b) After what time will the ships be 160 nautical miles apart? . 3. A puck of mass m slides on a frictionless table while attached to a hanging cylinder of mass M by a cord through a hole in the table. What speed keeps the cylinder at rest ? . 4. In figure, a 12kg block is released from rest on a 300 frictionless incline. Below the block is a spring that can be compressed 2.0cm by a force of 270N. The block momentarily stops when it compresses the spring by 5.5cm. (a) How far does the block move down the incline from its rest position to this stopping point? ;(b)What is the speed of the block just as it touches the spring? . 5. The uniform solid block in figure has mass M and edge lengths a, b and c. Calculate its rotational inertia about an axis through one corner and perpendicular to the large faces. . 6. In a playground, there is a small merry-go-round of radius 1.20m and mass 180kg. Its radius of gyration(旋转)() is 91.0cm. A child of mass 44.0kg runs at a speed of 3.00m/s along a path that tangent to the rim of the initially stat