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 :

The strong nuclear force holds the nucleus of an atom together.
Somehow, it overcomes the electrical force of repulsion between protons in the nucleus, which all have the same charge but still stay close together somehow. (b)
In a constant acceleration of 3m per second, after 10 seconds,
3 x 10 = 30
B. 30m/s is your answer
hope this helps XD
911.1×155.9 = 14,202.49
14,202.49 in 3 significant figures would be either 14,200 or 1.42×10^4