The density of the substance is<u> 10.5 g/cm³.</u>
The jewelry is made out of <u>Silver.</u>
Density ρ is defined as the ratio of mass <em>m</em> of the substance to its volume V<em>. </em> The cylinder contains a volume <em>V₁ of water</em> and when the jewelry is immersed in it, the total volume of water and the jewelry is found to be V₂.
The volume <em>V</em> of the jewelry is given by,

Substitute 48.6 ml for <em>V₁ </em>and 61.2 ml for V₂.

calculate the density ρ of the jewelry using the expression,

Substitute 132.6 g for <em>m</em> and 12.6 ml for <em>V</em>.

Since  ,
,
The density of the jewelry is <u> 10.5 g/cm³.</u>
From standard tables, it can be seen that the substance used to make the jewelry is <u>silver</u><em><u>, </u></em>which has a density 10.5 g/cm³.
 
        
             
        
        
        
The answer is speed: 4.7 km/h, velocity: 3.3 km/h.
Distances and time are given:
d1 =  4 km
d2 = 3 km
d3 = 5 km
t = 1.5 h
The speed can be expressed as a distance (d) divided by time (t). The average speed (s) is total distance travelled divided by time:
s = (d1 + d2)/t = (4+3)/1.5 = 7/1.5 = 4.7 km/h
The average velocity (v) is total displacement (d₁) from the starting point divided by time. Since Mary's starting point was home, and she walked to the supermarket, which is 5.0 kilometers from her own home, her displacement is 5 km:
v = d₁/t = 5/1.5 = 3.3 km/h
        
             
        
        
        
P=w/t
w=15
t=3
therefore, 5 watts (b)
        
             
        
        
        
I don't really know the answer but maybe north pole and south pole?
        
             
        
        
        
Answer:
a)   C = 4,012 10⁻¹⁴ F, b)  Q = 1.6 10⁻¹¹ C
, c)   U = 3.21 10⁻¹¹ J
Explanation:
a) The capacitance of a capacitor is
        C = k e₀ A / d
Let's calculate
        C = 4 8.85 10⁻¹² 17 10⁻⁴ / 0.150 10⁻²
        C = 4,012 10⁻¹⁴ F
b) let's look  the charge
         C = Q / ΔV
          Q = C ΔV
          Q = 4,012 10⁻¹⁴ 400
          Q = 1.6 10⁻¹¹ C
c) The stored energy
         U = ½ C ΔV²
         U = ½ 4,012 10⁻¹⁴  400²
         U = 3.21 10⁻¹¹ J