課程名稱︰普通物理學甲上
課程性質︰系內必帶
課程教師︰王立民
開課學院：工學院
開課系所︰土木工程學系
考試日期（年月日）︰98/12/17
考試時限（分鐘）：110min
是否需發放獎勵金：是，謝謝
（如未明確表示，則不予發放）
試題 :
普通物理平時考(CH10,11)
試題附圖：http://i814.photobucket.com/albums/zz65/kenyang0531/Untitled-3.jpg
1. Figure 1 shows an arrangement of 15 identical solid spheres that have been
glued together in a rod-like shape of length L = 3.0 m and (total) mass M =
150.0 mg. The arrangement can rotate about a perpendicular axis through its
central disk point O. (a) What is the rotational inertia of the arrangement
about the axis?(10%) (b) If we approximated the arrangement as being a
uniform rod of mass M an length L, what percentage error would we make in
using the formula in Table 10-2e to calculate the rotational inertia?(5%)
(c) If there are N (N is odd) identical solid spheres, please re-estimate
the inertia in (a).(10%) (d) Show that if N→∞, the inertia is equal to
the result in Table 10-2e. [Hint:2^2+4^2+....+(N-1)^2=N(N^2-1)/6]
2.In Fig. 2, the pully which can be regarded as a disk, is mounted in
horizontal frictionless bearings with a radius of 20.0 cm and mass of 0.2 kg,
and the inclined plane are frictionless. Block A has a mass of 1.0 kg, block
B has a mass of 2.0 kg, and angle θ is 30°. When released form rest,
(without the cord clipping on the pully) (a) What is the magnitude of the
block's acceleration? What is the tension in the cord that supports (b) Block
A and (c) the Block B? (d) What is the magnitude of the pulley's angular
acceleration?(20%)
3.In Fig. 3, a solid brass ball of mass 0.280 g will roll smoothly along a loop
-the-loop track when released from rest along the straight section. The
circular loop has radius R = 14.0 cm, and the ball has radius r = 2.0 cm. (a)
What is h if the ball is on the verge of leaving the track when it reaches
the top of the loop? If the ball is released at height h = 84.0 cm, what are
the (b) magnitude of the normal force from the loop acting on tha ball at the
point Q? and (c) the magnitude of the normal force from the loop acting on
the ball at the lowest point P?(15%)
4.In Fig.4, a small 50 g disk with a radius of 1 cm goes smooth rolling motion
down a friction surface through height h = 20 cm and then sticks to a
uniform rod of mass 100 g and length 40 cm. The rod pivots about point O
through angle θ before momentarily stopping. (a) Find the speed of the ball
at the lowest point bofore the collision, and (b) find θ.(20%)
5.Proof the result : I=M(a^2+b^2)/12 as shown in Table 10-2 i.(15%) [Hint:Using
I=ML^2/12 for a uniform rod with a perpendicular rotation axis through it's
center.]
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