Math Problem Statement

The motion of a spring subject to frictional or damping forces is modeled by the equation of motion s(t) = 2e^(-1.7t) * sin(2πt). Find the velocity after t seconds.

Solution

The problem describes the motion of a spring subject to damping or frictional forces, modeled by a function of the form:

s(t)=2e1.7tsin(2πt)s(t) = 2e^{-1.7t} \sin(2\pi t)

where s(t)s(t) is the position of the point on the spring in centimeters, and tt is the time in seconds. We are tasked with finding the velocity after tt seconds.

Step 1: Differentiate to Find Velocity

The velocity v(t)v(t) is the derivative of the position function s(t)s(t) with respect to time tt. To do this, we'll apply the product rule and chain rule.

The product rule states: ddt[f(t)g(t)]=f(t)g(t)+f(t)g(t)\frac{d}{dt}[f(t)g(t)] = f'(t)g(t) + f(t)g'(t)

Here, f(t)=2e1.7tf(t) = 2e^{-1.7t} and g(t)=sin(2πt)g(t) = \sin(2\pi t).

Step 2: Derivatives

  • f(t)=2(1.7)e1.7t=3.4e1.7tf'(t) = 2 \cdot (-1.7) e^{-1.7t} = -3.4 e^{-1.7t}
  • g(t)=2πcos(2πt)g'(t) = 2\pi \cos(2\pi t)

Step 3: Applying the Product Rule

Using the product rule: v(t)=ddt[2e1.7tsin(2πt)]=(3.4e1.7t)sin(2πt)+(2e1.7t)(2πcos(2πt))v(t) = \frac{d}{dt}[2e^{-1.7t} \sin(2\pi t)] = (-3.4 e^{-1.7t}) \sin(2\pi t) + (2e^{-1.7t})(2\pi \cos(2\pi t))

Simplify this expression: v(t)=3.4e1.7tsin(2πt)+4πe1.7tcos(2πt)v(t) = -3.4 e^{-1.7t} \sin(2\pi t) + 4\pi e^{-1.7t} \cos(2\pi t)

Thus, the velocity function is: v(t)=e1.7t(3.4sin(2πt)+4πcos(2πt))v(t) = e^{-1.7t} \left( -3.4 \sin(2\pi t) + 4\pi \cos(2\pi t) \right)

This is the expression for the velocity at any time tt.

Would you like further details or have any questions?

Related Questions:

  1. What is the velocity at a specific time, such as t=1t = 1 second?
  2. How would the velocity change if the damping constant (1.7) is increased?
  3. How does the oscillatory motion (given by the sine term) affect the overall behavior of the spring?
  4. Can we compute the maximum velocity the spring reaches during its motion?
  5. How does the velocity change as tt \to \infty, and why?

Tip: For oscillating systems, the exponential decay function eate^{-at} typically models damping, reducing the amplitude of the motion over time.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Product Rule
Trigonometric Functions
Exponential Decay

Formulas

Product rule: d/dt [f(t)g(t)] = f'(t)g(t) + f(t)g'(t)
Derivative of e^(-at): -a * e^(-at)
Derivative of sin(kt): k * cos(kt)

Theorems

Product Rule of Differentiation
Chain Rule of Differentiation

Suitable Grade Level

Grade 12 or College Level Calculus