课程名称︰普通物理学甲上 期中
课程性质︰大一
课程教师︰王名儒
开课学院：
开课系所︰数学系
考试日期（年月日）︰2015/11/10
考试时限（分钟）：110分钟
试题 :
1. What the uncertainty of measured area for a rectangle with width 12.0 +-0.2cm and length 10.0 +-0.1 cm, assuming the width and length measurements are uncorrelated?
2. A projectile's launch speed is 6.0 times that of the speed at ts maximum height. Find the launch angle .
3. A boy whirls a stone in a horizontal circle of radius 1.5 m and at height 2.0 meter above ground. The string breaks, and the stone files off horizontally and strikes the ground alter traveling a horizontal distance of 10 m. What is the magnitude of the centripetal acceleration of the stone during the circular motion?
4. Find the work done by the force F(x,y) =y^2 i+ 2xy j along the line y=2x form point (0,0) to (2,4), all in SI units. Is this a conservative force?
5. A 15 kg package is moving at a speed of 10 m/s vertically upward when it explodes into three fragments: a 2.0 Kg fragment is shot upward with an initial speed of 20 m/s and a 3.0 kg fragment is shot in the positive direction of a horizontal x axis with an initial speed of 5.0 m/s.
Find the speed of the third fragment right after the explosion and the total kinetic energy provided by the explosion.
6. A tall chimney falls over when its base is ruptured. Threat the chimney as a thin rod of length L; at what angle is the tangential acceleration equal to G at the top?
7.The rolling motion of a wheel with radius R on the ground can be viewed as a constant speed motion Vcm of the wheel center and a constant rotation with angular Speed ɯ (= Vcm/R ) around the center. Show that the rolling can also be viewed as a pure rotation with the same angular speed ɯ about the contact point between the wheel and the ground
8.For an isolated system with N particles, prove that the angular momentum of the system is conserved.
9.A uniform cube of sicte length L rests on a horizontal floor. A horizontal push is applied perpendicular to one of the vertical faces along its central line. If the push is
gradually increasing,the cube will slide for the push below a height h from the floor
and the cube will tip otherwise (i.e. above h). Find the coefficient of static friction between cube and Door.
10.Write done the Keplers laws for planet motion. You can use the special case,uniform circular motion, to derive the formula of the 3rd law.