※ [本文转录自 NTU-Exam 看板 #1IQJx2Oz ]
作者: Standpoint (旋风企鹅) 看板: NTU-Exam
标题: [试题] 101上 王名儒 普通物理学甲上 期中考
时间: Thu Oct 24 23:37:36 2013
1. A ball is thrown horizontally from the top of a 20-m high hill. It strikes
the ground at an angle of 45度. With what speed was it thrown ?
2. A block is suspended by a rope from the ceiling of a car. When the car
rounds a 50-m radius horizontal curve at 20 m/s, what angle does the rod make
with the vertical ?
3. Find the change of the kinetic energy of a particle moving under the force
F(x,y) = x^2y i + xy^2 j along the curve y = x^2 from point (0,0) to (2,4).
SI units are assumed.
4. Describe properties of the frictional force (for both static and kinetic).
Draw a simple graph to show the relationship between the magnitude of the
frictional force and the applied external force.
5. A uniform string having mass m is fixed on a frictionless table with half
its total length, L/2. The other half is hung vertically outside this table.
If this string is released freely at one moment, how long will it take for
this string being fully out of the table ?
6. A 30 kg steel block is dropped from a height of 20 cm above a thin thin
rod made of aluminum. The Young's modulus of aluminum is 70*10^9 N/m^2, the
cross-sectional area of this rod is 1.0 cm^2 and the rod length is 10 cm.
Find the maximum distance which the rod is compressed assuming the ground
and the block are perfectly rigid.
7. A playground merry-go-round has a radius of 3.0 m and a rotational inertia
of 600 kg m^2. It is initially spinning at 0.8 rad/s when a 20 kg child
crawls from the center to the rim. When the child reaches the rim, the angular
velocity of the merry-go-round becomes ?
8. Find the rotational energy of a disk with radius R and mass m rolling from
the rest on a 45度 ramp for a distance L.
9. Find the gravitational force experienced by a particle (mass m) at a
distance r from the center of a uniform spherical star with mass M and
10. A large tank with height H is filled with water. There are two small hole
in the bottom, one with radius r and the other 2r. Find the speeds of water
leaving the small hole and the large hole.