Math Problem Statement

A particle's position is given by p(t) = t^4/2 - 4t^2 + 10 meters for t > 0 seconds. The particle gets closest to the origin when its velocity is zero. Find how close the particle is to the origin for t > 0.

Solution

To solve this problem, we need to determine when the particle’s velocity is zero, as that’s when it is closest to the origin.

Given Information

The position p(t)p(t) of the particle is: p(t)=t424t2+10p(t) = \frac{t^4}{2} - 4t^2 + 10 for t>0t > 0 seconds.

Step 1: Find the Velocity Function

Velocity is the derivative of the position function p(t)p(t): v(t)=p(t)=ddt(t424t2+10)v(t) = p'(t) = \frac{d}{dt} \left( \frac{t^4}{2} - 4t^2 + 10 \right)

Calculating the derivative term by term:

  1. ddt(t42)=2t3\frac{d}{dt} \left( \frac{t^4}{2} \right) = 2t^3
  2. ddt(4t2)=8t\frac{d}{dt} \left( -4t^2 \right) = -8t
  3. ddt(10)=0\frac{d}{dt} (10) = 0

Thus, v(t)=2t38tv(t) = 2t^3 - 8t

Step 2: Set the Velocity to Zero

To find when the particle is closest to the origin, set v(t)=0v(t) = 0: 2t38t=02t^3 - 8t = 0

Factor out 2t2t: 2t(t24)=02t(t^2 - 4) = 0

This gives: t=0ort2=4t = 0 \quad \text{or} \quad t^2 = 4

Since t>0t > 0, we discard t=0t = 0 and solve t2=4t^2 = 4: t=2t = 2

Step 3: Find the Position at t=2t = 2

Now, substitute t=2t = 2 into p(t)p(t) to find the position: p(2)=(2)424(2)2+10p(2) = \frac{(2)^4}{2} - 4 \cdot (2)^2 + 10 =16244+10= \frac{16}{2} - 4 \cdot 4 + 10 =816+10= 8 - 16 + 10 =2= 2

Conclusion

The particle is 2 meters from the origin when it is closest to it.

Answer: The closest distance to the origin is 2 meters.

Would you like more details on any step?


Here are five related questions for practice:

  1. How would you find the maximum distance from the origin using this function?
  2. If the position function was different, say p(t)=t33t+5p(t) = t^3 - 3t + 5, how would the solution change?
  3. What does the second derivative tell us about the behavior of the particle's motion?
  4. How would the solution change if we included negative values of tt?
  5. Can we determine if this point is a minimum using a second derivative test?

Tip: Always check that the value of tt falls within the specified domain when solving physics or calculus problems with constraints.

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Math Problem Analysis

Mathematical Concepts

Calculus
Differentiation
Velocity and Position Functions

Formulas

Velocity function v(t) = p'(t) where p(t) is the position function
Factorization of polynomial equations

Theorems

Setting derivative to zero to find critical points

Suitable Grade Level

Grade 12 or College Calculus