Phys.2211 practicing problems
• Review the tests, quizzes.
• Practice ‘stop to think’ Chapt. 14, 16,17
and Homework # 8, 9
• Summarize the homework.
• prepare your own formula sheet
Final exam. schedule:
MWF 9:00 class: April 29 , Friday 8:00 am
11:00 class: April 27, Wed. 10:45 am
comprehensive problems
1.You may use this way to get a bullet speed. Suppose a bullet of mass
8.00 g is fired into a block of mass 2.50 Kg initially at rest at the edge of
a frictionless table of height 1.00m. The bullet remains in the block, and
after impact the block lands a distance 2.00 m from the bottom of the
table, Determine the initial speed of the bullet. (review perfectly inelastic
collision and projectile motion. V(bullet) = 1388m/s)
(2) A ball of mass m is attached to a string of length L. It is
being swung in a vertical circle with enough speed so that
the string remains taut throughout the ball's motion.
• Find :
• (1) Tb-Tt, the difference between the tension in the string at the
bottom relative to that at the top of the circle in terms of m, g ( see
your homework #7)
• (2) find the centripetal acceleration difference at the bottom and the
top
3. See the problem 10.42, ( at homework #7)
suppose the collision between the packages is elastic
(1) to what height does the package of mass m rebound?
( 1/3m)
(2) what is the kinetic energy of the block of 2m, and what is the
percentage of this kinetic energy to total kinetic energy? (8/9 = 89%)
(3) if m and 2m stick together after collision, what is the kinetic energy left
after collision.(1/3 mgh)
4. See the problem 12.71, (page 382 Homework #7), if we neglect the
friction between m1 and table. The pulley mass is mp, (i) what is the
acceleration of the system? (ii) If m2 start h (m) from the ground what is the
speed when m2 hit the ground, ( b/c in this problem ,acceleration is a
constant, so that you can use V2 = Vi2 + 2ah). (iii) you also can get that
speed using mechanical energy conservation law. The results for two ways
should be the same.
5. Santa Claus stands on the top of the hill, he is sending
the Christmas gifts to you, a sphere, a cylinder, and circular
hoop all of mass M and radius R. they are rolling down
from rest at the same instant of time, which will get the
bottom of the hill first? Why?
• Please show the time for each one
6.
•
As you did in your lab for the ring pendulum, suppose
this ring pendulum consists of a thin metal ring that can
be suspended from a knife edge.
a) What is the period if the ring diameter is 10 cm
D
(suppose the ring is very thin) T  2 g
• b) If you plot log T vs log D( diameter) what is the slope?
• c) If you had data from a lot of T and D, you may plot T2
vs D figure. how you use a slope to find the gravitational
acceleration g?
7. See the figure: Can you increase the gas temperature
without changing the pressure? If so, describe how you
would do it. If not, explain why not.
Answer: you can heat the gas on the bottom, but not add
any mass on the piston, so mass maintains a constant
pressure in the cylinder, but heat energy is transferred into
the gas, makes temperature increase, as well as gas will
expand from PΔV=nRΔT, you may get how much
temperature increasing. This is constant pressure process,
Q = nCp ΔT
8. 0.10 of a monatomic gas follows the process shown in the figure, how much
heat energy is transferred to or from the gas during the process 1→2? (240J)
how much heat energy is transferred to or from the gas during the process
2→3? (410J)
What is the total change of thermal energy of the gas ( see homework #9,
17.59, you will find the molar specific heat of gases on page 524; table 17.4)