Answer:
C ) Electric charge.
Explanation:
Amber is used in the experiments related to static electricity.
In electrostatics, elektron was the word used as a variation to amber, by the Greeks. Amber buttons, when rubbed with cloth, attracted hair.
Studies showed that when amber is rubbed with fur, fur became negatively charged and amber became positively charged. That is because amber loses its electrons to fur.
Primary Circular Reactions (1-4 months): This substage involves coordinating sensation and new schemas. For example, a child may suck his or her thumb by accident and then later intentionally repeat the action. These actions are repeated because the infant finds them pleasurable.
Lamina occupies x² + y² = 14y. Outside circle is x² + y² = 49
To find the mass of lamina, integrate given density function over the region
m = ∫∫D P(x, y) dA
Subtitute x = r cosФ and y = r sinФ in x² + y² = 14y
and x² + y² = 49
x² + y² = 14y
(r cosФ)² + ( rsinФ)² = 14(rsinФ)
r² = 14r sin Ф
x² +y² = 49
r² = 49
r = 7
Cntre mass (-x. -y)
-x= i/m ∫∫D xp(x,y) dA = 1/m∫∫ (r cosФ) p( r, Ф)r
dr dФ
-y = 1/m∫∫D yp(x, y) dA = 1/m ∫∫D (r sinФ) p(r, Ф) r drФ
where m = ∫∫D p(x, y) dA
The point beneath surface where rock breaks and an earthquake is produced is known as the Focus.