Explanation:
Given that,
Initial speed of the billiard ball 1, u = 30i cm/s
Initial speed of another billiard ball 2, u' = 40j cm/s
After the collision,
Final speed of first ball, v = 50 cm/s
Final speed of second ball, v' = 0 (as it stops)
Let us consider that both balls have same mass i.e. m
Initial kinetic energy of the system is :

Final kinetic energy of the system is :

The change in kinetic energy of the system is equal to the difference of final and initial kinetic energy as :
So, the change in kinetic energy of the system as a result of the collision is equal to 0.
That's silly. The volume of a gas is very intimately related
to the volume of its enclosure. In fact, they're identical,
because a gas always expands to fill whatever you put it in.
The answer is B, time is always the independent variable
This should help u find it
The answer is "Conduct an experiment" :)