true and false - 10
Elasticity is the property of objects them to their original shape and size after the forces deforming them are removed.
T
Most liquids demonstrate restoring forces and tend to return to their original shape and size after small distortions.
F
Rubber is one of the most elastic materials within its elastic limit.
T
Let us support a spring from above and stretch it by hanging a mass on the bottom end. The spring will stretch until the elastic restoring force is great enough to support the density of the object.
F
The periodic motion is a characteristic of elastic objects moving under the influence of Coulomb ́s law type forces.
F
A vast majority of solids obey Hooke ́s law when they are deformed slightly from their equilibrium configurations.
T
The period of the periodic motion is defined as the time required to comlete one full cycle.
T
The amplitude of periodic motion is the maximum distance of moving away from the equilibrium position.
T
Periodic motion occurs at one or more natural or resonant frequencies that depend on the physical properties of the system such as mass, length and stiffness.
T
For a spring-mass system, the stiffer the spring, the higher the deformity.
F
An important feature of resonance is that a system will tend to
out its resonant frequency, irrespectively of the nature of the energy source that puts it in motion.
T
A transverse wave is defined as a wave in which the particles of the medium oscillate back and forth along a straight line parallel to the direction of wave propagation.
F
The wavelength is given by Lamba=v/f=vT, where v is the propagation speed, f is the frequency, and T is the time of the motion.
F
Sound is a traveling pressure wave which propagates through the air, solids or liquid materials. It can also travel through a vacuum.
F
Human audible range include frequencies between 20 to 20000Hz.
T
The speed of sound depends on the atmospheric pressure but is independent of the frequency and amplitude of the sound wave.
F
Light is a transverse wave which travels through a vacuum at the enormous velocity of 3*10^9m/s.
F
The perceived color of light is a measurement of the speed of light.
F
Interference refers to the multiplication of two or more waves which pass through the same point in space.
F
When a wave is produced in an elastic string, it will reflect the fixed end of the string and come back. The reflected wave may interfere constructively or destructively with the incident wave.
T
Suppose the length of the elastic string corresponds to a half-wavelength or an integer multiple of half-wavelengths. Then the interference between reflected waves will cause the condition known as a traveling wave.
F
Male voices are usually lower than female voices because the vocal cords are more massive.
T
Ultrasound consists of frequencies above the range of human
hearing, starting at about 20kHz and going upward without a definite upper limit.
T
An echo is a reflection of a sound wave at the boundary between two materials of different acoustic impedances.
T
The speed of sound in tissue mainly depends upon the mass, so the outlines produced are largely outlines of mass changes.
F
The resolution of ultrasound techniques depends on the ultrasound wavelength. The wavelength should be considerably smaller than the object in order to visualize it clearly.
T
We see ordinary objects clearly because the light wavelengths which are reflected to our eyes are much higher than the objects perceived.
F
A Doppler ultrasound technique is used in vascular studies to
detect vascular constrictions by measuring the velocity of blood flow.
T
Infrasound in water produces large numbers of tiny bubbles via a process known as cavitation.
F
The effect of cavitation is used in ultrasonic nebulizers.
T