課程名稱︰物理丙
課程性質︰森林環境學群及生物材料學群必修
課程教師︰李慶德
開課學院：生農學院
開課系所︰森林環資系
考試時間︰95年11月22日
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
七題選五題答
1.A cannon on the ground can fire a ball at 50m/s at 53度 above the horizontal
The target is 35m above the ground. At what horizontal distance from the
target should the cannon be located？
2.A car travels along a hilly road. The top of a hill has a curvature of
radius of 30m.
(a)What is the maximum speed possible if the car is not to lose contact
with the road？
(b)At this speed , what would be the apparent weight of a 65-kg passenger
when the car is at the bottom of a valley of radius of curvature
40m？
3.A 10-g bullet moving at 500m/s strikes a ballistic pendulum of mass 3.0kg
the bullet emerges with a speed of 100m/s
(a)To what height does the pendulum bob rise？
(b)How much work was done by the bullet in passing through the block？
4.A 2-kg block slides on a frictionless horizontal surface and is connected
on one side of a spring with spring constant k=50N/m as show in Fig.1. The
other side is connected to a 4-kg block that hangs vertically. The system
starts from rest with the spring unextended.
(a)What is the maximum extension of the spring？
(b)What is the speed of the 4-kg block when the extension of the spring is
60cm？
│ k 2kg 滑輪
╞﹏﹏﹏﹏﹏﹏█—○┐
└────────┐│
││
││
│█
│4kg
│
5.A crate of mass m is dropped onto a conveyor belt that moves at a constant
speed v as shown in Fig.2.The coefficient of kinetic friction is μk.
(a)What is the work done by friction？
(b)How far does the crate move before reaching its final speed v？
(c)When the crate reaches its final speed, how far has the belt moved？
N
↑
█→fk
===============================→v
○ ↓(mg) ○
6.On fast highways the outside edge of curve is raised. Such banking prevents
vehicles from slipping sideways if there is not enough friction to provide
the centripedal force.
A car of mass 1500kg rounds a circular curve of racius 20m that is banked at
37度 to the horizontal. The road is slippery, so the coefficient of static
friction is only 0.15
(a)Find the maximum safe speed at which the car can travel without skidding
(b)Is it possible for a car to go around a banked curve even if there is no
friction ？
7.A vertical spring extends 40cm when a 1-kg block is suspended from it.
It is pulled down a further 10cm and released.
(a)Write an expression for the total potential energy U(x), where x is the
extension of the spring.Set U=0 at x=0
(b)What is its speed when it returns to the equilibrium position？
(c)What is its maximum height above the equilibrium point？
(d)Where would the potential energy of the system be zero？
(e)Sketch U(x)
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