Your answers for a), b), and c) are correct.  Good work !
d). The high noise levels in Technology and PE are more of 
a concern to the teachers than to the students because the 
students are only in there for 1 or 2 periods a day, but the 
Technology and PE teachers are in there ALL day.
e).  Mr. Jones can't hear as high frequency as Jenny can because 
he is much older than Jenny is.  Sadly, even without damage due to 
loud noise, the ability to hear high frequencies does decrease with age.
f).  The wooden surfaces in the gym cause the gym to be louder 
than it would be if it had carpet on the floor.  Carpet ... and soft 
walls and ceilings ... absorb a lot of the sound that hits them.  
But hard surfaces don't absorb much of the sound that hits them, 
so it just keeps bouncing around until it finally fades away.  
You can see this easily ... just go into the gym at your school, clap 
your hands once, and notice how long you keep hearing the sound 
after you clap.  
        
                    
             
        
        
        
Answer:
Mass = 4152kg
Explanation:
Given 
L = 208m
I = 154A 
V = 0.245V
Density = 3610 kg/m3
ρ = 4.23 x 10-8Ω·m = resistivity of wire
Resistance R = ρL/ A 
R = voltage / current = V/I = 0.245/154 = 1.59×10-³ohms
1.59×10-³ = 4.23 x 10-⁸×208/A 
Rearranging,
A = 4.23 x 10-⁸×208/1.59×10-³
A = 5.53×10-³m²
Mass = density × volume
Volume = L×A = 208×5.53×10-³m³= 1.15m³
Mass = 3610×1.15 = 4152kg
 
        
                    
             
        
        
        
Answer:
A. 181.24 N
Explanation:
The magnitude of hte electrostatic force between two charged objects is given by the equation

where
k is the Coulomb's constant
q1, q2 are the magnitudes of the two charges
r is the separation between the charges
In this problem, we have:
 is the magnitude of the 1st charge
 is the magnitude of the 1st charge
 is the magnitude of the 2nd charge
 is the magnitude of the 2nd charge
r = 2.5 cm = 0.025 m is the separation between the charges
Therefore, the magnitude of the electric force is:

So, the closest answer is 
A) 181.24 N
 
        
             
        
        
        
Answer:
43.7 °C
Explanation:
 = Coefficient of linear expansion of brass =
 = Coefficient of linear expansion of brass = 
 = Coefficient of linear expansion of steel =
 = Coefficient of linear expansion of steel = 
 = Initial length of brass = 31 cm
 = Initial length of brass = 31 cm
 = Initial length of steel = 11 m
 = Initial length of steel = 11 m
 = Total change in length = 3 mm
 = Total change in length = 3 mm
Total change in length would be


The final temperature is 43.7 °C
 
        
             
        
        
        
The central force acting on the electron as it revolves in a circular orbit is  .
.
The given parameters;
- <em>speed of electron, v = 2.2 x 10⁶ m/s</em>
- <em>radius of the circle, r = 4.63 x 10⁻¹¹ m</em>
<em />
The central force acting on the electron as it revolves in a circular orbit is calculated as follows;

where;
 is mass of electron = 9.11 x 10⁻³¹ kg
 is mass of electron = 9.11 x 10⁻³¹ kg

Thus, the central force acting on the electron as it revolves in a circular orbit is  .
.
Learn more about centripetal force here:brainly.com/question/20905151