LOL xaM Flashcards
What is the range of Hooke’s law validity?
Region until the elasticity limit (elastic)
What does an isotropic material mean?
A material with uniform properties throughout in all directions.
What is the difference between a strain and mechanical stress?
Mechanical stress is a force per unit area within materials that arises from
externally applied forces, while a strain is the measure of the deformation of
the material.
What are the two basic components of a bone?
Flexible fibers of collagen and brittle chains of the calcium-rich mineral
hydroxyapatite.
What are the factors affecting the elasticity of bone?
The stress duration, the fluid content of the specimen, bone temperature, the
vascular pattern of the bone.
If the initial length of a spring is doubled,
the spring’s constant become twice smaller.
Which of these statements for simple harmonic oscillations is true?
The instant acceleration of an oscillating object is the largest when it is the
furthest from equilibrium.
Which two of these oscillation types can be used to describe a beating heart?
Forced, because the heart receives continuous input from the nervous system.
· Damped, because in natural conditions there are always energy losses due to friction.
Angular frequency is
the frequency of a steadily recurring phenomenon expressed in radians per
second;
A model based on a harmonic oscillator describing human walking and balance
can be represented with the sinusoidal trajectory of the center of mass of a
subject.
During one full oscillation the phase changes:
by 2π radians (360 degrees)
Which wave types can be used to characterize a sound wave propagating in
air? Select two options.
Mechanical wave
Longitudinal wave
Sound intensity
○ Is proportional to the sound power
○ Is proportional to the sound energy
○ Unit is watts per square meter
What is the quantity defined as the time for one sound wave?
Period
Which sound has a higher pitch?
Craziest and highest one
The sound intensity I is measured as sound power P per unit area A in Watts per square meter (W/m2)?
True
Every 10dB sound intensity doubles?
False
When two (or more) waves travel simultaneously in the same medium, the total disturbance in the medium is at each point the vectorial sum of the individual disturbances produced by each wave
True
It is possible to focus the light, but impossible to focus the sound
False
The distance between the nearest equal points on the sound wave is called
amplitude.
False
The response of the ear to the sound intensity is closer to being linear than
logarithmic
False
Acoustic impedance depends on the density of the material and the speed of
sound in a given material.
True
The sound wave in the air is a mechanical transverse wave.
False
The nerves in the ear are not the only ones that respond to the sound pressure
wave, as most of the skin contains nerves that are more sensitive to pressure
variations
False
When the ultrasonic wave passes an interface of two mediums that have similar
acoustic impedance, almost no reflection of this wave occurs.
True
If the sound source is moving towards the observer, the amplitude of the sound
will seem to be larger, compared to an unmoving source at the same distance
away.
False
Medical ultrasound uses the Doppler effect to measure the velocity of the blood
flow. This can be used to detect blood clots, for example, in vein thrombosis
diagnostics.
True
The ultrasound wavelength increases when the frequency is decreased, but the
light wavelength increases when the frequency is increased.
False
This relationship between frequency (f), wavelength (λ), and speed (v) is true for
wave motion.
True
Piezoelectric crystals are used to generate ultrasound. The same crystals are also
used to detect echoes in ultrasonography.
True
Acoustic impedance is a property of a tissue, which describes resistance to the
propagation of an ultrasound wave through the tissue.
Acoustic impedance value dependent on the tissue thickness.
True
