Answer:
The force that required an object to move is greater than friction force. The opposite force for an object in motion is the friction force (assuming that the surface where the object lies is rough as most real objects are). This force is needed to be overcome to set the object to motion.
Explanation:
I think it is C in my personal opinion
The frequency of a wave is equal to the linear speed divided the wavelength. so in equation form.
f = v / l
so the wavlength
l = v / f
where f is the frequency
v iss the linear speed
l is the wavelength
l = ( 5100 m/s ) / ( 2.2 Mhz ) ( 10^6 hz / 1 Mhz )
f = 0.0023 m
f = 2.3 mm
An alloy that contains mainly copper and tin is bronze
To solve this problem it is necessary to apply the concepts related to Sound Intensity. The unit most used in the logarithmic scale is the decibel and mathematically this is expressed as

Where,
= Sound intensity level in decibels
I = Acoustic intensity on the linear scale
Hearing threshold
According to the values, the total intensity is 32 times the linear intensity and the value in decibels is 83dB
So:




Therefore the sound intensity due to one person is 67.948dB