Answer:
<em>c. because the rod polarizes the metal.</em>
Explanation:
Bringing the negatively charged rod close to the neutral metal ball causes the neutral metal ball to be polarized with induced positive charge on it. The polarizing of the formally neutral metal ball is due to the negative charge on the metal rod (bodies induce a charge opposite of their own charge on a nearby neutral body). The ball and rod then attract themselves because bodies with opposite charges attract each other, unlike bodies with same charges that repel each other.
Answer:
so his far point according to this pair of glass is 200 cm
Explanation:
power of old pair of corrective glasses is given as

now we have



now we know that for normal vision the maximum distance of vision is for infinite distance
so by lens formula we have



so his far point according to this pair of glass is 200 cm
It says: The bigger the distance between objects the smaller the gravity between them.
Given :
The ball of a ballpoint pen is 0.5 mm in diameter and has an ASTM grain size of 12.
To Find :
How many grains are there in the ball?
Solution :
Volume of ball of the ballpoint is :

Now, grain size of 12 has about 520000 grains/mm³.
Therefore, number of grains are :
