Physics 3LB Final Questions With Complete Solutions
(w1)INTRODUCTION: THE EKG AND THE EEG
In medical practice, two instruments that use the oscilloscope
are the ELECTROCARDIOGRAM (EKG) and the
ELECTROENCEPHALOGRAM (EEG). The EKG records the
electrical potential differences that occur within the heart every
time it beats. The EEG records the total electrical output of the
brain cells.
READING 1
The electrocardiogram is a record of potential differences at the
surface of the body. However, the heart is not the only source of
potentials at the body surface, and therefore it is necessary to
distinguish between those potentials coming from the heart and
those from other organs [1]. Every muscle within the body
undergoes potential changes as its fibers contract. The
magnitude of the action potentials for all nerves and all muscle
fibers is about 120 mV. The motion of any skeletal muscle can
give rise to body surface potential differences comparable to
EKG potentials. To lim Correct Answers Skeletal fiber
(w1)Oscilloscope channel addition problem. Read the following
oscilloscope settings carefully. Suppose you display a 1 kHz, 2
V sine wave in channel A and a DC, 1V signal in channel B
with sensitivities set on 1V/div. You select 'Add' so that the two
signals are combined and you readjust the position so the trace is
in the middle of the screen. If you switch the signal in channel B
from DC to AC, what will happen? (Draw a picture if it helps.)
Correct Answers The trace jumps down 1 division
,(w1)Oscilloscope time base problem. You are asked to display a
1 kHz sine wave signal on the screen. Since the period T is
related to the frequency f by the formula T = 1 / f, the period of
this wave is 1/(103/s)=1ms, so a reasonable setting for the
"Time/div" dial is 1 ms/div. But suppose you select an
inappropriate setting for the Time/div dial by mistake. What
would you see if you set the dial on 1 μ s/div? 100 ms/div?
Correct Answers A (nearly) horizontal line on 1 μ s/div and
many (nearly) vertical lines of 100 ms/div
(w1)The EEG is NOT used for diagnostic purposes for which of
the following medical issues? Correct Answers All of the
above can use the EEG for diagnostic purposes
(w1)The encephalograph (EEG) produces very weak electrical
signals (approximately 1/100 as strong as does the
electrocardiograph); the signal must be amplified over
10,000,000 times in order to be recorded. The large current
resulting from the amplification varies exactly as the original
[4].
Brain waves are evoked primarily from the cerebral cortex and
result from input from pathways projected through the thalamus.
The wavelike patterns arise from synchronized cyclic activity of
groups of neurons. One's EEG is as unique as one's fingerprints,
but the EEG changes with the state of consciousness or emotion
[5].
Often brain waves are irregular, but under some conditions
distinct patterns can be recorded. Four main kinds of waves have
been distinguished: the alpha, beta, delta and theta, waves [5].
These waves originate in specific regions of the brain and are
, evoked during certain states of mental activity. The alpha-w
Correct Answers Delta
(w1)Which component of the EKG causes the heart to contract?
Correct Answers P wave
(w5)
Collision derivation problem. A car is released from rest on a
frictionless inclined plane (Figure 5.3). EXAMPLES: Calculate
the momentum pi at the end of the plane in terms of the
measured quantities x, y, L, and m. Assume θ is very small so
that h/L is approximately equal to y/x. (Hint: use conservation of
energy and the fact that K=1/2mv2=p2/2m.)
[Answer: ]
If a car suffers a nearly elastic collision it will coast back up the
ramp a distance Lf before reversing direction. What is the
momentum pf immediately following the collision? The general
expression for the change in momentum suffered in a collision is
Δis Δ=
what is Δp (the magnitude of Δ) in terms of x, y, Li, Lf ,and m?
[Answer:
This is the expression you should use in the experiment. Make
sure you understand how to derive these equations.
QUESTION:
If the car has a mass of 0.2 kg, the ratio of height to width of the
ramp is 12/75, the initial displ Correct Answers 0.0189
(w5)
(w1)INTRODUCTION: THE EKG AND THE EEG
In medical practice, two instruments that use the oscilloscope
are the ELECTROCARDIOGRAM (EKG) and the
ELECTROENCEPHALOGRAM (EEG). The EKG records the
electrical potential differences that occur within the heart every
time it beats. The EEG records the total electrical output of the
brain cells.
READING 1
The electrocardiogram is a record of potential differences at the
surface of the body. However, the heart is not the only source of
potentials at the body surface, and therefore it is necessary to
distinguish between those potentials coming from the heart and
those from other organs [1]. Every muscle within the body
undergoes potential changes as its fibers contract. The
magnitude of the action potentials for all nerves and all muscle
fibers is about 120 mV. The motion of any skeletal muscle can
give rise to body surface potential differences comparable to
EKG potentials. To lim Correct Answers Skeletal fiber
(w1)Oscilloscope channel addition problem. Read the following
oscilloscope settings carefully. Suppose you display a 1 kHz, 2
V sine wave in channel A and a DC, 1V signal in channel B
with sensitivities set on 1V/div. You select 'Add' so that the two
signals are combined and you readjust the position so the trace is
in the middle of the screen. If you switch the signal in channel B
from DC to AC, what will happen? (Draw a picture if it helps.)
Correct Answers The trace jumps down 1 division
,(w1)Oscilloscope time base problem. You are asked to display a
1 kHz sine wave signal on the screen. Since the period T is
related to the frequency f by the formula T = 1 / f, the period of
this wave is 1/(103/s)=1ms, so a reasonable setting for the
"Time/div" dial is 1 ms/div. But suppose you select an
inappropriate setting for the Time/div dial by mistake. What
would you see if you set the dial on 1 μ s/div? 100 ms/div?
Correct Answers A (nearly) horizontal line on 1 μ s/div and
many (nearly) vertical lines of 100 ms/div
(w1)The EEG is NOT used for diagnostic purposes for which of
the following medical issues? Correct Answers All of the
above can use the EEG for diagnostic purposes
(w1)The encephalograph (EEG) produces very weak electrical
signals (approximately 1/100 as strong as does the
electrocardiograph); the signal must be amplified over
10,000,000 times in order to be recorded. The large current
resulting from the amplification varies exactly as the original
[4].
Brain waves are evoked primarily from the cerebral cortex and
result from input from pathways projected through the thalamus.
The wavelike patterns arise from synchronized cyclic activity of
groups of neurons. One's EEG is as unique as one's fingerprints,
but the EEG changes with the state of consciousness or emotion
[5].
Often brain waves are irregular, but under some conditions
distinct patterns can be recorded. Four main kinds of waves have
been distinguished: the alpha, beta, delta and theta, waves [5].
These waves originate in specific regions of the brain and are
, evoked during certain states of mental activity. The alpha-w
Correct Answers Delta
(w1)Which component of the EKG causes the heart to contract?
Correct Answers P wave
(w5)
Collision derivation problem. A car is released from rest on a
frictionless inclined plane (Figure 5.3). EXAMPLES: Calculate
the momentum pi at the end of the plane in terms of the
measured quantities x, y, L, and m. Assume θ is very small so
that h/L is approximately equal to y/x. (Hint: use conservation of
energy and the fact that K=1/2mv2=p2/2m.)
[Answer: ]
If a car suffers a nearly elastic collision it will coast back up the
ramp a distance Lf before reversing direction. What is the
momentum pf immediately following the collision? The general
expression for the change in momentum suffered in a collision is
Δis Δ=
what is Δp (the magnitude of Δ) in terms of x, y, Li, Lf ,and m?
[Answer:
This is the expression you should use in the experiment. Make
sure you understand how to derive these equations.
QUESTION:
If the car has a mass of 0.2 kg, the ratio of height to width of the
ramp is 12/75, the initial displ Correct Answers 0.0189
(w5)
