Chapter 5: Problem 37
Solve the given problems by determinants. In a laboratory experiment to measure the acceleration of an object, the distances traveled by the object were recorded for three different time intervals. These data led to the following equations: $$\begin{array}{l} s_{0}+2 v_{0}+2 a=20 \\ s_{0}+4 v_{0}+8 a=54 \\ s_{0}+6 v_{0}+18 a=104 \end{array}$$ Here, \(s_{0}\) is the initial displacement (in \(\mathrm{ft}\) ), \(v_{0}\) is the initial velocity (in \(\mathrm{ft} / \mathrm{s})\), and \(a\) is the acceleration (in \(\mathrm{ft} / \mathrm{s}^{2}\) ). Find \(s_{0}, v_{0},\) and \(a\).
Short Answer
Step by step solution
Write the system of equations in matrix form
Find the determinant of the coefficient matrix \(A\)
Calculate \(|A_{s_0}|\) by replacing the first column with \(\mathbf{b}\)
Calculate \(|A_{v_0}|\) by replacing the second column with \(\mathbf{b}\)
Calculate \(|A_a|\) by replacing the third column with \(\mathbf{b}\)
Solve for \(s_0\), \(v_0\), and \(a\) using Cramer's Rule
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cramer's Rule
Cramer's Rule allows us to express the solution of a system of equations in terms of the determinants of the matrices formed by replacing one column of the original matrix with the constant vector. For solving a system of equations, each variable is calculated by dividing the determinant of the respective modified matrix by the determinant of the original coefficient matrix.
- For a variable such as \( s_0 \), you replace the first column of the coefficient matrix \( A \) with the constants from the constant vector \( \mathbf{b} \) to find \( |A_{s_0}| \).
- Repeat the process for other variables by replacing their respective columns.
- If \(|A|\) is zero, the system might not have a unique solution.
Matrix Algebra
A system of linear equations can be represented in matrix form \( A\mathbf{x} = \mathbf{b} \), where:
- \( A \) is the coefficient matrix containing coefficients of the system.
- \( \mathbf{x} \) is the variable vector holding the unknowns \( s_0, v_0, \) and \( a \).
- \( \mathbf{b} \) is the constant vector that includes the results of the equations.
System of Equations
The objective is to find values of the unknown variables \( s_0 \), \( v_0 \), and \( a \) from:
- Each equation is developed based on physical measurements.
- The system aligns multiple conditions that the solution must satisfy simultaneously.
- Solving the system provides an intersection point that meets all conditions.
Acceleration Calculation
In physics, acceleration is given in terms of displacement, velocity, and time through equations of motion:
- The initial displacement \( s_0 \) and initial velocity \( v_0 \) form part of the equations.
- By finding these variables, we determine how much the object's velocity changes per unit time.
- Acceleration \( (a) \) units are in \( \mathrm{ft} / \mathrm{s}^{2} \), indicating the rate of change.