Answer:
Radio waves have a wavelength between
and 
While,
X rays have a wavelength between 1m and 10km.
=> It is one of the condition of diffraction that the obstacle (coming in the way) must be comparable with the size of the wavelength.
=> This shows, that radio waves have a wavelength which is comparable with the size of buildings and can really easily diffract through it
=> While, X-rays are big enough to diffract through the wall.
So, if an X-ray technician stands behind a wall during the use of her machine, she will remain safe.
Answer:19.5 m
Explanation:
Given
coefficient of kinetic Friction 
Initial speed 
Friction is present so it tries to stop to the object and stops it completely after moving certain distance let say s
maximum deceleration provided by friction is


using equation of motion

where 




There are two units of sound: intensity and in decibels. Decibels are not additive, you must convert it first to units of intensity (W/m²) using this formula:
dB = 10 log(I/10⁻¹²)
A. 100 dB = 10 log(I/10⁻¹²)
Solving for I,
I = 0.01 W/m²
90 dB = 10 log(I/10⁻¹²)
Solving for I,
I = 0.001
Ratio = 0.01/0.001 = 10
<em>Thus,the choir is 10 times more intense than the soloist.</em>
B. Since there are 90 singers, there would be 9 groups of 10-person choir that produces 100 dB or 0.01 W/m². The total intensity would be
Total intensity = 0.01 W/m² (original choir) + 0.001 W/m² (soloist) + 10(0.01 W/m²) (additional 90 singers) = 0.111 W/m²
dB = 10 log(0.111/10⁻¹²) = <em>110.45 dB</em>
C. Rock concert:
120 dB = 10 log(I/10⁻¹²)
Solving for I,
I = 1 W/m²
Ratio = 1/0.111 = 9
<em>Therefore, the rock concert is 9 times more intense than the choir concert.</em>
The equation Q=CV (Charge = product of Capacitance and potential difference) tells us that the maximum charge that can be stored on a capacitor is equal to the product of it's capacitance and the potential difference across it. In this case the potential difference across the capacitor will be 6.0V (assuming circuit resistance is negligable) and it has a capacitance of 15.7<span>μf or </span> 15.7x10^-6f, therefore charge equals (15.7x10^-6)x6=9.42x10^-5C (Coulombs).