Phys.2211 practicing problems
• Review the quizzes and tests.
• Practice ‘stop to think’ Chapt. 12, 14, 16, 17,
20. (1,2,3)
• Summarize the homework.
• prepare your own formula sheet
Final exam. schedule:
MWF class Dec. 10, Friday 8:00 -10:30am
MW class Dec. 13, Monday 4:15—6:45 pm
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. (see
Homework #7)
•
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.Three identical balls are thrown from the top of a building, all
with the same initial speed the first is thrown horizontally, the
second at some angle above the horizontal and third at some angle
below the horizontal.
Neglecting the air resistance, rank the speeds of the balls at the
instant each hits the ground
4. See the problem 10.42, ( at homework #7)
(1) If m and 2m stick together, after collision, what is the final velocity after
collision? [+(1/3) sqrt(2gh)] . What is the percentage of kinetic energy lost
after collision? (2/3 = 67%)
(2) If the collision between the packages is elastic
(i) what is the velocity of m? what is the velocity of 2m after collision?
(ii) to what height does the package of mass m rebound? [1/9 (3m)=1/3m]
(ii) What is the percentage of the total kinetic energy lost after collision? (0)
5 See the problem 12.71, (page 382 Homework #9), 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 (meters) from the ground what
is the speed when m2 hit the ground, (iii) you also can get that speed using
work and energy equation. Please do it.
6. 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 one has the
greatest speed of center of mass? which one will get the
bottom of the hill first? Why?
• Please show the time for each one
7. Two equal masses are attached to identical ideal
strings, length L, next to one another. One mass is
pulled 10o and the other pulled only 5o , then release.
The masses are released simultaneously. Which mass
reaches the vertical position( θ = 0o) first? Explain your
reasoning.
8. The figure shows a 2Kg mass riding on top of a 4Kg as it
oscillates on a frictionless surface. The spring constant is
100N/m and the coefficient of static friction between the
two blocks is 0.50. What is the angular frequency ω of the
system? What is the maximum oscillation amplitude for
which the upper block does not slip?
9. Homework 16.69 (homework # 11)
The 50 kg circular lead piston shown in the figure floats on 0.490 mol of
compressed air. The cylinder diameter is 10 cm.
1.What is the pressure of the air inside ( don’t forget atmosphere pressure)
2. If we heat the air without change the pressure, raise the temperature from
30 C to 200 C, how far does the piton move
3. how much heat Q is transferred ( Cp=29J/mol K) Q=nCpΔT
4. what is the change in thermal energy ΔE(th) = W + Q
10. ( Homework 17.59 #11) 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? (244J)
how much heat energy is transferred to or from the gas during the process
2→3? (406J)
What is the work done during the process 2 →3?
What is the total change of thermal energy of the gas