Problem 1.
(50%)
WeB WorK set
# 7.
Problem 2.
(25%)
Two identical blocks
of mass m = 0.1 kg are at rest on a nearly frictionless
surface, connected by an un-stretched massless spring with spring constant
k = 100 N/m. At
time t = 0 s a constant
force F = 5 N, directed
towards the right, is applied to block 2 (see upper diagram). At a later time the blocks are in a new position, as shown
in the lower diagram.
a.
At this later time, what is the sum of the kinetic energy and potential
energy of the two-block system?
b.
What is the translational kinetic energy of the two-block system?
c.
What is the speed of the center of mass of the two-block system?
d.
What is the vibrational kinetic energy of the two-block system? Note that the spring is stretched.
Problem 3. (25%)
In the software download
area of the Physics 141 website you will find two movies that show
two-dimensional elastic and inelastic collisions. Use
Capstone to analyze these movies and determine the position of the
center of mass as function of time. Use
the following steps in this analysis:
- Download the movie clips from the Physics 141 website (elastic and inelastic collisions).
- Follow the instructions on this page to analyse the videos.
-
After completing your data entry, you will have the x and y positions
for both pucks for all frames and for both data scollisions. You can now determine the position of the
center of mass of the system as function of time.
Hand
in the two graphs showing the
x and y position of the center of mass as function of time
for the elastic and the inelastic collisions and for each movie determine
the average speed of the center of mass.
On the front of your written solutions to Problems 2 and 3, please copy and sign the following statement:
I affirm that I have not given or received any unauthorized help on this assignment, and that this work is my own.
The solutions to Problems 2 and 3 must be submitted in pdf format to Box.
Problem 4.
(Optional; 25% extra credit)
From the software download area you will be able to download a skeleton
VPython code, doubleMassSpringSystem.which simulates problem 2 with
the exception of the spring (the skeleton code assumes that a massless
wire connects the two blocks). Modify the code to include the spring,
as shown in the Figure, and create graphs of the translational kinetic
energy and the vibrational kinetic energy as function of time for k =
100 N/m and for
k = 1 N/m. Send these graphs, a description of how
you tested your program to ensure it is running properly, and the actual
program via email to Professor Wolfs (wolfs@pas.rochester.edu). The name of the file with the program
should be hw07p04XXYYYYYYYY.py where XX are your initials and YYYYYYYY
is your student id number.
