If an object's speed changes, or if it changes the direction it's moving in,
then there must be forces acting on it. There is no other way for any of
these things to happen.
Once in a while, there may be <em><u>a group</u></em> of forces (two or more) acting on
an object, and the group of forces may turn out to be "balanced". When
that happens, the object's speed will remain constant, and ... if the speed
is not zero ... it will continue moving in a straight line. In that case, it's not
possible to tell by looking at it whether there are any forces acting on it.
Explanation: Newton's first law of motion states that a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force. This is also known as the law of inertia. Inertia is the tendency of an object to remain at rest or remain in motion.
1. The balls move to the opposite direction but the same speed. This represents Newton's third law of motion.
2. The total momentum before and after the collision stays constant or is conserved.
3. If the masses were the same, the velocities of both balls after the collision would exchange.
4 and 5. Use momentum balance to solve for the final velocities.
Answer:
The concentration of OH⁻ in the mixture is 0.05 M
Explanation:
The reaction of neutralization between HCl and NaOH is the following:
H⁺(aq) + OH⁻(aq) ⇄ H₂O(l)
The number of moles of HCl is:

Similarly, the number of moles of NaOH is:

Now, from the reaction of HCl and NaOH we have the following number of moles of NaOH remaining:

Finally, the concentration of OH⁻ in the mixture is:
Therefore, the concentration of OH⁻ in the mixture is 0.05 M.
I hope it helps you!