Explanation :
Displacement refers to the distance between the final and the initial position. Hence the displacement of the ball will be the difference between the initial and the final displacement.
Let the initial position be 0.
Final position = 8 cm
So the difference between initial position and final position = 0 – 8 = - 8 cm.
So the billiard ball comes to rest 8.0 cm behind its orbital position.
Question :
If a body acquires a charge of -0.02 C, has it gained or lost electrons? Many?
Solution :
We know, charge gained is shown by negative sign.
Since, charged acquired is given as -0.02 C .
Therefore, it is body has gained electrons.
Now, number of electrons is given by :

Hence, this is the required solution.
Weather balloons are filled with only a small amount of helium because the __Volume__. of the balloon will increase as the air pressure decreases at higher altitudes.