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# PHYS 2108- Midterm Exam Guide - Comprehensive Notes for the exam ( 12 pages long!)

Department
Physics
Course Code
PHYS 2108
Professor
browne
Study Guide
Midterm

This preview shows pages 1-3. to view the full 12 pages of the document. LSU
PHYS 2108
MIDTERM EXAM
STUDY GUIDE

Only pages 1-3 are available for preview. Some parts have been intentionally blurred. Only pages 1-3 are available for preview. Some parts have been intentionally blurred. PHYSICS 2108 LAB FINAL
LAB 1
Pre-Lab:
oHow many significant digits are in this number? 0.00001980. 4
oTwo graduate students measure the strength of an MRI’s magnetic field to have
the following values:
Student A: 8.10 +/- 0.09 T
Student B: 8.04 +/- 0.05 T
Do the two students agree for the strength of the magnetic field? Yes
oIf I want to compare values before and after an event, I would use: percent
change
oIf I want to compare two separate values, I would use: percent difference
oIf I want to compare predicted results to my measure results, I would use: percent
error
oDoes setting up a best fit line mean “connecting the dots”? No
oSuppose we want to linearize by substitution the formula for dependent variable
Kinetic Energy (K) with independent variable velocity (v). if the original equation
is K= (1/2)mv2, what will our “new” independent variable (x) be when we “map”
this onto y=mx + b? v2
Post-Lab:
oYou perform an experiment in slacking off at work by clocking out earlier each
week and seeing how it affects your paycheck. Properly title the graph and label
the axes for the plot your collected data.
Title: pay received vs. time worked
Y: pay received (\$)
X: time worked (hours)
oThe known area of a table is 1.50 m2. You measure the length of the table to be
1.25 m and the width to be 1.25 m. what is the percent error between the known
area of the table and the measured area of the table you calculate using A=L*W?
4.17
percent error: measured area – known area/known area * 100
measured area: 1.25 * 1.25
oMomentum is defined as mass times velocity. You find the mass of a car to be
2077.48 kg and the velocity of the car to be 6.9 m/s, giving you a momentum of
14334.612 kg-m/s. round this momentum to the correct number of significant
digits. 14000
Due to 6.9 m/s only being 2 significant figures.
oOne example of tolerance “that matters in the real world” can be found in
radiation oncology clinics. Physicians will prescribe some dose of radiation to a
patient’s tumor that must be delivered within a certain tolerance (or range of
doses) in order to control the tumor. If a physician prescribes 52.9 Gy +/- 2.00%,
what is the maximum dose the patient can receive (in Gy)? Note: A Gy is measure
of the amount of energy deposited per unit mass.
53.9
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Only pages 1-3 are available for preview. Some parts have been intentionally blurred. oHumans live an average of 79.8 years in the US. Express this time in units of days
if the conversion factor is exactly 365.25 days. Round your answer to the correct
number of significant digits as given by the original time in years.
29100 days
365 days in a year  365*79.8 = 29127, sig figs29100
oThe speed of light is 299,792,458 m/s. however, most physicists round this
number to 3x108 m/s. what is the percent difference in these values using the
correct number of sig figs? Assume the exact speed of the light is the reference
value.
0.07 %
percent difference: rounded # - actual #/rounded # * 100.
LAB 2
Pre-Lab:
oWhich of the following instruments will you be using to make measurements this
week in lab? Triple beam balance, meter stick, and digital caliper.
oIn MKS units, final answers of time should always be given in which of the
following units? Seconds
oIn this lab (and others) we will be doing calculations with the gravitational
constant g= 9.8 m/s2. Because we will treat it as a mathematical constant assumed
to be known exactly, how many significant digits does it contain? Infinite digits
of precision and infinite significant digits.
o
What is the least-count of the ruler? 0.1 cm
From the picture, what is the measured value (use the correct number of
significant digits and interpolate if necessary)? 10.5 cm
o
The picture represents low accuracy and low precision
Post-Lab:
oYou measure a sheet of paper. The width is 8.46 inches and the length is 11.29
inches. What is the area of the paper in MKS units (m2)?
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