Chapter 5: Problem 22
Evaluate the expression using the given values. \(m v^{2} ; m=6 \frac{1}{2}, v=-\frac{2}{5}\)
Short Answer
Expert verified
Question: Evaluate the expression \(m v^{2}\) for \(m=6\frac{1}{2}\) and \(v=-\frac{2}{5}\).
Answer: \(\frac{26}{25}\)
Step by step solution
01
Insert the given values into the expression
Replace \(m\) with \(6\frac{1}{2}\) and \(v\) with \(-\frac{2}{5}\) in the expression \(m v^{2}\). This gives us \((6\frac{1}{2})(-\frac{2}{5})^2\).
02
Convert the mixed number to an improper fraction
Convert \(6\frac{1}{2}\) into an improper fraction. Since \(6\frac{1}{2}=6+1/2\), we can write it as \(6*2/2+1/2\), which equals \(\frac{12+1}{2}\). Therefore, \(6\frac{1}{2} = \frac{13}{2}\).
Now our expression becomes: \((\frac{13}{2})(-\frac{2}{5})^2\)
03
Square the velocity term
Square the given value of \(v\), which is \(-\frac{2}{5}\). We have \((-\frac{2}{5})^2 = \frac{(-2)^2}{5^2} = \frac{4}{25}\).
Now our expression becomes: \((\frac{13}{2})(\frac{4}{25})\)
04
Multiply the fractions
Multiply the two fractions as follows:
\(\frac{13}{2} * \frac{4}{25} = \frac{13*4}{2*25} = \frac{52}{50}\).
05
Simplify the fraction
Divide the numerator and the denominator of the obtained fraction by their greatest common divisor (GCD). The GCD of \(52\) and \(50\) is \(2\).
So, \(\frac{52}{50} = \frac{52/2}{50/2} = \frac{26}{25}\).
Hence, the evaluated expression is \(\frac{26}{25}\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Fractions
Fractions are a way to represent parts of a whole. They consist of a numerator and a denominator separated by a line. For example, in the fraction \(\frac{3}{4}\), \(3\) is the numerator indicating how many parts we have, and \(4\) is the denominator showing the total number of equal parts.
When working with fractions, there are several key operations:
Understanding how to manipulate fractions is crucial for evaluating expressions.
When working with fractions, there are several key operations:
- **Addition/Subtraction**: Fractions must have the same denominator to be added or subtracted. For example, \(\frac{1}{2} + \frac{1}{3}\) requires finding a common denominator, like \(6\), resulting in \(\frac{3}{6} + \frac{2}{6} = \frac{5}{6}\).
- **Multiplication**: Simply multiply the numerators and denominators. For example, \(\frac{2}{3} \times \frac{3}{4} = \frac{6}{12} = \frac{1}{2}\).
- **Division**: Flip the second fraction and multiply. For instance, \(\frac{2}{3} \div \frac{3}{4} = \frac{2}{3} \times \frac{4}{3} = \frac{8}{9}\).
Understanding how to manipulate fractions is crucial for evaluating expressions.
Mixed Numbers
Mixed numbers consist of a whole number and a fraction. For example, \(6\frac{1}{2}\) includes the whole number \(6\) and the fraction \(\frac{1}{2}\). They're a convenient way to express numbers greater than one.
To use them in mathematical calculations, it's often necessary to convert them to improper fractions:
To use them in mathematical calculations, it's often necessary to convert them to improper fractions:
- **Convert the Whole Number**: Multiply the whole number by the denominator of the fraction part.
- **Add the Fraction**: Add this product to the numerator of the fraction part.
- **Create Fraction**: Use the sum as the new numerator, with the original denominator remaining the same.
- Multiply \(6\) by \(2\): \(6 \times 2 = 12\)
- Add the numerator \(1\): \(12 + 1 = 13\)
- Write the fraction \(\frac{13}{2}\)
Squaring Numbers
Squaring a number means multiplying it by itself. It's a fundamental operation in algebra and often used in various equations and expressions. In mathematical terms, squaring \(a\) is represented as \(a^2\).
When squaring fractions, the process remains the same:
When squaring fractions, the process remains the same:
- **Numerator**: Square the numerator.
- **Denominator**: Square the denominator.
- **Result**: Keep the result as a new fraction.
- Square \(-2\): \((-2)^2 = 4\)
- Square \(5\): \(5^2 = 25\)
- Result: \(\frac{4}{25}\)