Download Accelerated Physics Simple Harmonic Motion Lab Answer Sheets

Accelerated Physics Simple Harmonic Motion Lab
Introduction
All objects have a natural frequency at which they like to vibrate. Think about a
playground swing and how you have to time your pushes in order to get it to
reach a maximum height above the ground. You are providing your pushes at the
natural frequency of the swing which science people call the "resonance
frequency" of the object/system.
You are now about to embark on an experiment that investigates vibration
motion. Think of systems that vibrate and you will immediately become aware of
the usefulness of this investigation. What do you think automobile engineers who
design shock absorbers have to be aware of or an architect involved in the
design of a concert hall? The music you hear from an instrument or stereo
system is also the result of vibration?
Experiment
Set up the equipment according to the following diagram. You will investigate the
motion of an oscillating (vibrating) spring by using a motion detector positioned
so to read the vertical displacement over time. In this investigation you will use
our knowledge of vibrating springs to determine the spring force constant.
Experimental Setup
Part 1: Procedure
i.
Prepare the computer for data collection by opening “02 Spring.cmbl”
from the Physics with Vernier experiment files of Logger Pro. Two
graphs will appear on the screen. The vertical axis of the distance
graph is scaled from 0 to 1.5 m. The vertical axis of the velocity graph
is scaled from – 1 to + 1 m/s. The horizontal axis of both graphs has
time scaled from 0 to 10 s.
ii.
Place the motion detector so that it is facing upward, about 1m below a
mass suspended from the spring. Put a protective cage over the
motion detector.
iii.
Attach the spring to the pulley and put a small mass from your weight
set on the end of the spring so that when you pull it down a couple of
cm and let it go, the mass oscillates up and down and not side to side.
Find the mass of the spring plus added mass and write it in the
data table. Pull the mass down again and let it go. Press
and
record the motion of the mass over time.
iv.
If you do not see a smooth graph, the mass most likely was not in the
beam of the Motion Detector. Adjust the aim or look for interfering
objects and try again. You might want to try sticking a small index card
to the bottom of the mass or change the distance between the mass
and the motion detector if the graph persists on being jagged. Print
when you have a good graph. Make sure it has an appropriate title
and your name(s) are on it as a footnote!
Part 1: Questions
1. Find the time taken for one complete oscillation. (note: can select examine
from the analyze menu or drag over the correct interval and read the t in the
bottom left of the screen). Enter this value in your result table. Check this
value using the multiple peaks on your graph. Using other peaks write down
four other values for this time in the space provided. Then find the average
time and record it. We call this time the period.
2. Is the period constant or does it change with time?
3. What indicated by your graph changes with time?
4. Using the period find out how many vibrations there are per second.
5. What effect does pulling the mass down more (or less) have on the period?
Make a prediction and then investigate this question. Try to explain what
you observe. Go to experiment – store latest run. You can use Data –Hide
Data Set to toggle between graphs.
Results Table
Part
Total
Mass
(kg)
Period 1
(s)
Period 2
(s)
Period 3
(s)
Ffinal
(N)
xfinal
(m)
Period 4
(s)
Average
Period
(s)
1
2
Finitial
(N)
xinitial
(m)
F
(N)
x
(m)
3
Part 2: Procedure
You will now determine the spring force constant k, by measuring the period for
various masses.
I.
II.
Add more mass to your spring and repeat part 1. Record your data in
the table. Determine the average period.
Repeat for three more masses on your spring. Do not overstretch the
spring!
Part 2: Questions
1. Plot a straight line graph involving period and mass whose slope enables
you to determine the spring constant, k. Make sure that your graph is suitably
titled with correct labels and your name(s) typed as a subscript.
2. Determine the k value for your spring using the slope of your graph.
Part 3: Procedure
I.
You will now find the spring constant (which tells you how many
Newton’s of force are needed per unit distance of stretch) the easy way,
and compare it with your answer above.
You will need a meter stick and a spring scale. Lay the spring horizontal and apply two different
forces with the spring scale. Use the meter stick to measure the end position of the spring for
each force. Record your measurements in the data table. Be careful NOT to overstretch the
spring!
Part 3: Questions
1. Find the spring constant according to:
k=
Change in applied force (F)
Extension of the spring ( x)
k = _______________ N/m
2. Determine the percentage difference between you answers for k found from
parts 2 and 3.
% difference = difference in k value x 100 %
average of the two
% difference = _______________
3. Account for any differences between your two values for k found in parts 2
and 3
Accelerated Physics Simple Harmonic Motion Lab Answer Sheets
Name ____________________________________ Date____________ Hr. ___
Show all work for the calculations needed to answer each question. Attach
your graphs to the back of this packet
Results Table
Part
(10 pts)
Total
Mass
(kg)
Period 1
(s)
Period 2
(s)
Period 3
(s)
Ffinal
(N)
xfinal
(m)
Period 4
(s)
Average
Period
(s)
1
2
Finitial
(N)
xinitial
(m)
F
(N)
x
(m)
3
Part 1
1. Find the time taken for one complete oscillation. Show calc! (2 pts)
2. Is the period constant or does it change with time? (1 pt)
3. What indicated by your graph changes with time? (1 pt)
4. Using the period find out how many vibrations there are per second. Show
calc! (2 pts)
5. What effect does pulling the mass down more (or less) have on the
period?
Prediction (2 pts)–
What you found out: include period values (3 pts) –
Explanation of observation (3 pts)-
Part 2
6. Using the slope of your straight-line graph, determine the spring constant, k,
for your spring. Show all work (4 pts)
k= ___________ N/m
Part 3
7. Value of k from physical measurement __________________ N/m
Show calc!
(3 pts)
8. Percentage difference between your answers for k found from parts 2 and 3.
(3 pts) Show calc!
9. Account for any differences between your two values for k found in parts 2
and 3 (3 pts)