Chapter 5: Problem 5
For any spring obeying Hooke's Law, show that the work done in stretching a spring a distance \(d\) is given by \(W=\frac{1}{2} k d^{2}\).
Short Answer
Expert verified
The work done is given by \( W = \frac{1}{2} k d^{2} \) for a spring obeying Hooke's Law.
Step by step solution
01
Understanding Hooke's Law
Hooke's Law states that the force required to stretch or compress a spring by a distance \( x \) from its equilibrium position is proportional to \( x \). Mathematically, it's given by \( F = kx \), where \( k \) is the spring constant.
02
Relating Work to Force and Displacement
The work \( W \) done by a force in moving an object through a displacement is given by the integral of force with respect to displacement. For a variable force like in a spring, it's \( W = \int F(x) \, dx \).
03
Determining the Expression for Work Done
Substituting Hooke's Law (\( F = kx \)) into the work integral gives \( W = \int kx \, dx \). The limits of integration are from 0 to \( d \), as the displacement starts from 0 and goes to \( d \).
04
Solving the Integral
To find the work done, evaluate the integral \( W = \int_{0}^{d} kx \, dx = k \int_{0}^{d} x \, dx \). This integral is \( k \left[ \frac{x^2}{2} \right]_{0}^{d} \).
05
Evaluating the Result
Substituting the limits, we find \( W = k \left( \frac{d^2}{2} - \frac{0^2}{2} \right) = \frac{1}{2} kd^2 \). Thus, the work done in stretching the spring by a distance \( d \) is \( W = \frac{1}{2} kd^2 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Spring Constant
In the world of physics, the spring constant is a key characteristic that describes a spring's ability to resist deformation. It is denoted by the letter \( k \) and is a measure of the stiffness of the spring. A higher spring constant means a stiffer spring, requiring more force to stretch or compress it.
- Hooke's Law formula that includes the spring constant is \( F = kx \), where \( F \) is the force applied to the spring and \( x \) is the displacement from the spring’s equilibrium position.
- The spring constant is crucial for predicting how much force is needed for a certain displacement, important in various applications from vehicle suspensions to measuring devices.
- Spring constants vary depending on material and construction, allowing designers to tailor springs for specific needs.
Work Done
Work done is a fundamental concept in physics that refers to the energy transferred to or from a system by a force acting over a distance. In the context of a spring, work is done when a force stretches or compresses it.
- For a spring following Hooke's Law, the work done \( W \) is given by \( W = \frac{1}{2} kd^2 \). This equation shows that work depends on the spring constant \( k \) and the square of the distance \( d \) the spring is stretched.
- The equation reveals that the work done is directly proportional to the spring constant and quadratically proportional to the distance.
- This formula results from integrating the force over the distance from 0 to \( d \), reflecting the way force varies with displacement in a spring.
Integral Calculus
Integral calculus is a branch of mathematics concerned with calculating areas under curves, finding volumes, and solving problems involving accumulation. It is essential for deriving and understanding physical laws involving changing quantities.
- In the exercise, integral calculus is used to determine the work done by integrating the force function \( F(x) = kx \) over the distance \( x \) from 0 to \( d \).
- This involves evaluating the integral \( W = \int_{0}^{d} kx \, dx \), which equals \( k \left[ \frac{x^2}{2} \right]_{0}^{d} = \frac{1}{2} kd^2 \).
- The process of integration helps in finding work done by a variable force, capturing how small changes accumulate over a range.
- This mathematical tool is pivotal in physics and engineering, allowing for the calculation of quantities that are not constant but change with respect to time or space.