Answer:
The intensity level in the room is 63 dB
Explanation:
To calculate the intensity of sound in the room, we use the equation of definition of decibels
      β = 10 log (I / Io)      (1)
With “I” the sound intensity and “Io” the threshold intensity 1.0 10⁻⁻¹² W/m²
To calculate the intensity we will use the initial data and remember the power of the emitted sound is constant, in addition that the sound propagates in three-dimensional form or on a spherical surface
       I = P/A    ⇒    P = I A
 The area of a sphere is 4 π r², where I can calculate of 1
      β/10 = log (I/Io)
    I / Io = 
    I = Io  
    I = 1 10⁻¹² 10⁽¹⁰⁰/¹⁰⁾   = 1 10⁻¹² 10¹⁰
    I = 1.0 10⁻² W
With this we can calculate the intensity for a distance of 20 m
  I  = 1.0 10⁻² / ( 4π 20²)
  I =  2.0 10⁻⁶ W/m²
We have already found the intensity at the point of interest, so we can calculate the intensity in decibels at this point with equation 1
     β = 10 log(2.0 10⁻⁶ / 1.0 10⁻¹²)
     β = 10 log ( 2 10⁶) = 10  6.3
     β = 63 dB
 The intensity level in the room is 63 dB
 
        
             
        
        
        
Answer:
Diagrammatic representation
 
        
             
        
        
        
Answer:
The change in momentum = -20000 kg m/s.
Explanation:
Mass m = 1000 kg
speed v₁ = 20 m/s
speed v₂ = 0 m/s
We know that,
The change in momentum
ΔP = m (Δv)
ΔP = m (v₂ - v₁)
      = 1000 (0 - 20)
      = 1000 (-20)
      = -20000 kg m/s
Thus, the change in momentum = -20000 kg m/s.
Note: negative sign indicates that the velocity is reducing when it hits the barrier.