1. **State the problem:**
We have a particle moving along the y-axis with velocity function $v(t) = 12t^2 - 24t$ for $t \geq 0$. The initial position is $x(0) = 10$ cm. We need to find the position $x(t)$ at the time when the velocity is minimum.
2. **Recall the relationship between position and velocity:**
Velocity is the derivative of position, so
$$v(t) = x'(t) = 12t^2 - 24t.$$
The position function is given by integrating velocity:
$$x(t) = \int v(t) dt = \int (12t^2 - 24t) dt.$$
3. **Find the position function:**
Integrate term-by-term:
$$x(t) = 12 \cdot \frac{t^3}{3} - 24 \cdot \frac{t^2}{2} + C = 4t^3 - 12t^2 + C.$$
Use initial condition $x(0) = 10$:
$$x(0) = 4 \cdot 0^3 - 12 \cdot 0^2 + C = C = 10.$$
So,
$$x(t) = 4t^3 - 12t^2 + 10.$$
4. **Find the time when velocity is minimum:**
Velocity minimum occurs where its derivative (acceleration) is zero and changes from negative to positive.
Calculate acceleration:
$$a(t) = v'(t) = \frac{d}{dt}(12t^2 - 24t) = 24t - 24.$$
Set acceleration to zero:
$$24t - 24 = 0 \implies 24t = 24 \implies t = 1.$$
5. **Verify minimum velocity at $t=1$:**
Check second derivative of velocity:
$$v''(t) = a'(t) = 24 > 0,$$ so velocity has a minimum at $t=1$.
6. **Find position at $t=1$:**
Substitute $t=1$ into $x(t)$:
$$x(1) = 4(1)^3 - 12(1)^2 + 10 = 4 - 12 + 10 = 2.$$
**Final answer:**
The position of the particle at minimum velocity is $\boxed{2}$ cm.
Position Minimum Velocity 77A361
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