课程名称︰普通物理学乙 课程性质︰必修 课程教师︰王建万 开课学院： 开课系所︰农化系 考试日期（年月日）︰2011.11.16 考试时限（分钟）：120分钟 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1. (a) What is the angular speed ω about the polar axis of a point on Earth's surface at latitude 60°N?(Earth rotates about that axis.) (b) What is the linear speed v of the point? What are (c) ω and (d) v for a point at the equator ? (Earth's radius R=6370km.) 2. A 8.00 kg blick with a speed 5.00 m/s collides with a 15.0 kg blick travels in the oringinal direction with a speed of 3.00 m/s. (a) What is the velocity of the 8.00 kg blick immediately after the collision? (b) By how much does the total kinetic energy of the system of two blocks change becausr of the collision? (c) Suppose, instead, that the 15.0 kg block ends up with a speed of 4.00 m/s . What then is the change in the total kinetic energy? (d) Account for the result you obtained in (c). 3. A conservative force F=(4.00x-8.00)i N, where x is in meters, acts on a particle moving along an x axis. The potential energy U associated with this force is assigned a value of 24.0J at x=0. (a) Write an expression for U as a positive potential energy? At what (c) negative value and (d) positive value of x is the potential energy equal to zero? 4. A circular-motion addict of mass 60.0kg rides a Ferris wheel around in a vertical circle of radius 16.0m at a constant speed of 6.00m/s (a) What is the period of the motion? What is the magnitude of the normal force on the addict from the seat when both go through (b) the highest point of the circular path and (c) the lowest point? (d) What is the centripetal acceleration of the addict during the motion? 5. A plane flies 600 km east from dity A to city B in 50.0 min and then 960km south in 1.20hr. For the total trip, what are the (a) magnitude and (b) direction of the plane's displacement, the (c) magnitude and (d) direction of its average velocity, and (e) tos average speed?? 6. The position of a particle moving along the x axis depends on the tome according to the equation x=c*t^2-b*t^3, where x is in meters and t in seconds. What ate the units of (a) constant c and (b) constand b? Let their numerical values be 6.00 and 3.00, respectively. (c) At what time does the particle reach its maximum positive x and (e) what is its displacement ? (f) Find its velocity at time 2.00s. (g) Find its acceleration at time 3.00s . 7. You throw a ball toward a wall at speed 40.0m/s and at angle θ=50° above the gorizontal (Fig.1) (Holiday第九版 Fig.4-35) . The wall is distance d=30.0m from the release point of the ball. (a) How far above the release point does the ball hit the wall? What are the (b) horizontal and (c) vertical components of ots velocity as it hit the wall? (d) When its hit , has it passed the highest point on its trajectory? 8. A block of mass m1=4.80kg on a frictionless plane at angle θ=30.0° is connected gy a cord over a massless, frictionless pulley to a second block of mass m2=3.00kg(Fig.2)(课本Fig5-52) . What are (a) the magnitude of the acceleration of each block, (b) the direction of the acceleration of the hanging block, (c) the tension in the cord, and (d) the resultant force acting on the pulley by the cord. 9. The block on Fig.3 (Fig.7-9(a)) lies on a horizontal frictoinless surface, and the spring constant is 40.0N/m. Initially, the spring is at its relaxed length and the block is stationary at position x=4.00N pulls the block in the positive direction of the x axis, stretching the spring until the block stops. When that stoppeng point is reached, what are (a) the position of the block, (b) the work that has been done on the block by the applied force, and (c) the work that has been done on the block by the spring force? During the block's displacement, what are (d) the block's position when its kinetic energy is maximum and (e) the value of that maximum kinetic energy? 10.The cable of the 2400 kg cab in Fig.4 (课本Fig.8-54) snaps when the cable is at rest at the first floor, wherer the cab bottom is a distance d=3.60m above a spring of spring constant k=0.16MN/m . A safety device clamps the cab against guide rails so that a constant frictional force of 4.40N opposesthe cab's motion. (a) Find the speed of the cab just before it hits the spring. (b) Find the maximum distance x that the spring is compressed (the frictional force still acts during this compression). (c) Fing the distance that the cab will bounce back up the shaft. (d) Using conservation of energy, find the approximate total distance that the cab will move cefore coming to rest.(Assume that the frictional force on the cab is negligible when the cab is stationary.) 11.In Fig.5 (课本Fig.10-38) ,block 1 has mass m1=400g, clock 2 has mass m2=540g, and the pulley, which is amounted on a horizontal axle with negligible friction, has radius R=6.00cm. when releaced from rest, block 2 falls 90.0cm in 6.00 s without the cord slipping on the pulley. (a) What id the magnitude of the acceleration of the blicks? What is the magnitude of the pulley's angular acceleration? (e) What is its rotational inertia? --

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