※ 引述《garychou (天然卷都是好人)》之铭言： 课程名称︰普通物理甲 课程性质︰选修 课程教师︰张宝棣 开课学院：电资学院 开课系所︰资工系 考试日期（年月日）︰99.10.22 考试时限（分钟）：120 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1.The water in a river flows uniformly at a constant speed of 2.5m/s between two parallel banks 80.0 m apart.You are to deliver a package directly across the river,but you can swim only at 1.50 m/s (a)If you choose to minimize the time you spend in the water,in what direction should you head ?(b)How far downstream will you be carried ?(c)What if ? If you choose to minimize the distance downstream that the river carries you,in what direction should you head ?(d)How far downstream will you be carried ? (20%) 2.A 10.0 Kg block rests on a 5-Kg bracket like the one in Figure 1. The 5-Kg bracket sits on a frictionless surface.The coefficients of friction between the 10-Kg block and the bracket on which it rests are μs=0.40 and μk=0.30. (a)What is the maximum force F that can be applied if the 10-Kg block is not to slide on the bracket ?(b)What is the corresponding acceleration of the 5-Kg bracket ?(10%) | F 5Kg← | ____→__ |-◎_____| | |________|__|__ ↓ 10Kg 3.A particle of mass 1.18 Kg is attached between two identical springs on a horizontal frictionless tabletop. The springs have force constant k and each is initially unstressed.(a)If a particle is pulled a distance x along a direction perpendicular to the initial configuration of the springs as shown in Fig. 2,find the potential energy of the system.Assume that L=1.20 m and k=40.0 N/m.If the particle is pulled 0.500 m to the right and then released, what is the its speed when it reaches the equilibrium point at x=0 ?(10%) ____ ________ | L | spring,k | O particle | L | spring,k ____|________ _____________ .\ . \ L . x\ => .---O . / L . / ___./_______ 4.A 5-kg block is held against a spring of force constant 20 N/cm,compressing in 3 cm.The block is released and the spring extends,pushing the block along a rough horizontal surface.The coefficient of friction between the surface and the block is 0.2.(a)Find the work done on the block by the spring as it extends from its compressed position to its equilibrium position.(b)Find the energy dissipated by friction while the block moves 3 cm to the equilibrium position of the spring.(c)What is the speed of the block when the spring is at its equilibrium position?(d)If the block is not attached to the spring,how far will it slide along the rough surface before coming to the rest ?(20%) 5.A 100 g ball on a 60-cm-long string is swung in a vertical circle about a point 200 cm above the floor.The tension in the string when the ball is at the very bottom of the circle is 5.0 N.A very sharp knife is suddenly inserted to cut the string directly below the point of support.Where does the ball hit the floor ?(5%) 6.A ball with mass m is aligned above a ball of mass M (with a separation) and the two are dropped simultaneously from height h.(Assume the radius of each ball is negligible compared to h.)(a)If M rebounds elastically from the floor and then m rebounds elastically from M,what ratio m/M results in M stopping upon its collisions with m ?(10%)(b)What height does m then reach?(5%) 7.Two curved inclines of two identical wedge-shaped masses M smoothly merge with a horizontal frictionless surface as indicated in Fig. 3.The curved surfaces of the inclines are also frictionless.Another mass m is released at rest from a height h on one of the inclines.(a)When m reaches the horizontal plane,is the mechanical energy of m and M conserved ? Is the total momentum of m and M conserved when m reaches the horizontal surface ? Why ?(5%)(b)After m reaches the horizontal plane,it encounters the right-hand wedge and ascends it to some height h'?Please explain.(5%)(c)Please express h' ? in terms of m,M, and h using the ideas in (a) and (b).(10%) Ｍ Ｍ │\▄← m /｜ │﹨ ∕｜ │ \ / ｜ │ Λ Λ ｜ │ ﹨ ∕ ｜ │ ﹨ 两个物体「相连」 ∕ ｜ │ ˋ 但是没有「相黏」 ˊ ｜ │ ╲ ╱ ｜ ｜ ╲ │ ╱ ｜ ｜ ︿ ↓ ︿ ｜ ｜ ‵*-,,-*′ ｜ ￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣ 突然发现班代没有附到这张图... 所以就帮他附上去 --

※ 发信站: 批踢踢实业坊(ptt.cc) ◆ From: 218.167.190.14