The process for rationalizing a denominator in a variable expression is the same as in a numeric expression. Here's a real-world example:

The kinetic energy of the car of a roller coaster is given by the formula:
[tex]\[ k = \frac{1}{2} m v^2, \][/tex]
where [tex]\( k \)[/tex] is kinetic energy, [tex]\( m \)[/tex] is the mass of the car, and [tex]\( v \)[/tex] is the velocity of the car.

Solving this formula for [tex]\( v \)[/tex], we get:
[tex]\[ v = \sqrt{\frac{2k}{m}}. \][/tex]

Which formula gives the velocity of the car in simplest form?

A. [tex]\( v = \frac{\sqrt{2km}}{2m} \)[/tex]
B. [tex]\( v = \frac{\sqrt{2km}}{m} \)[/tex]
C. [tex]\( v = \frac{\sqrt{2k}}{m} \)[/tex]



Answer :

To determine which formula gives the velocity [tex]\( v \)[/tex] of the car in its simplest form, we will start with the provided equation and simplify it step-by-step.

We are given:
[tex]\[ v = \sqrt{\frac{2k}{m}} \][/tex]

Now, let's work on rationalizing the denominator and simplifying the expression.

### Step-by-Step Simplification:
1. Start with the given equation:
[tex]\[ v = \sqrt{\frac{2k}{m}} \][/tex]

2. Rewrite the square root of a fraction as a fraction of square roots:
[tex]\[ v = \frac{\sqrt{2k}}{\sqrt{m}} \][/tex]

3. To rationalize the denominator, multiply the numerator and the denominator by [tex]\(\sqrt{m}\)[/tex]:
[tex]\[ v = \frac{\sqrt{2k} \cdot \sqrt{m}}{\sqrt{m} \cdot \sqrt{m}} \][/tex]

4. Simplify the denominator:
[tex]\[ \sqrt{m} \cdot \sqrt{m} = m \][/tex]
Therefore, our expression now is:
[tex]\[ v = \frac{\sqrt{2k} \cdot \sqrt{m}}{m} \][/tex]

5. Combine the square roots in the numerator:
[tex]\[ \sqrt{2k} \cdot \sqrt{m} = \sqrt{2km} \][/tex]
Therefore:
[tex]\[ v = \frac{\sqrt{2km}}{m} \][/tex]

We now have the formula in its simplest form:
[tex]\[ v = \frac{\sqrt{2km}}{m} \][/tex]

### Verifying the Options:
Upon comparing this simplified form with the provided options:

1. [tex]\( v = \frac{\sqrt{2km}}{2m} \)[/tex]
2. [tex]\( v = \frac{\sqrt{2km}}{m} \)[/tex]
3. [tex]\( v = \frac{\sqrt{2k}}{m} \)[/tex]

Clearly, the correct option is:
[tex]\[ \boxed{v = \frac{\sqrt{2km}}{m}} \][/tex]