1. **State the problem:** Given the position function $$x(t) = 0.050 \cos(10t + 6\pi)$$ in SI units, find the velocity $$v$$ and acceleration $$a$$ at time $$t = 0.10$$ seconds.
2. **Formulas used:**
- Velocity is the first derivative of position with respect to time: $$v(t) = \frac{dx}{dt}$$.
- Acceleration is the second derivative of position with respect to time: $$a(t) = \frac{d^2x}{dt^2}$$.
3. **Calculate velocity:**
$$v(t) = \frac{d}{dt} \left(0.050 \cos(10t + 6\pi)\right) = 0.050 \times (-\sin(10t + 6\pi)) \times 10 = -0.50 \sin(10t + 6\pi)$$
4. **Calculate acceleration:**
$$a(t) = \frac{d}{dt} v(t) = \frac{d}{dt} \left(-0.50 \sin(10t + 6\pi)\right) = -0.50 \times \cos(10t + 6\pi) \times 10 = -5.0 \cos(10t + 6\pi)$$
5. **Evaluate at $$t=0.10$$ s:**
Calculate the argument:
$$10 \times 0.10 + 6\pi = 1 + 6\pi$$
Since $$\sin(\theta)$$ and $$\cos(\theta)$$ are periodic with period $$2\pi$$, we can simplify:
$$6\pi = 3 \times 2\pi$$ so
$$\sin(1 + 6\pi) = \sin(1) \approx 0.8415$$
$$\cos(1 + 6\pi) = \cos(1) \approx 0.5403$$
6. **Calculate numeric values:**
$$v(0.10) = -0.50 \times 0.8415 = -0.42075 \approx -0.42$$
$$a(0.10) = -5.0 \times 0.5403 = -2.7015 \approx -2.70$$
7. **Compare with options:** None of the options exactly match these values, but the closest velocity is approximately $$-0.50$$ and acceleration approximately $$-0.25$$ in option (a). However, our acceleration is about $$-2.70$$, which is much larger in magnitude.
**Re-examining step 4:** The acceleration formula should be:
$$a(t) = \frac{d}{dt} v(t) = \frac{d}{dt} \left(-0.50 \sin(10t + 6\pi)\right) = -0.50 \times 10 \cos(10t + 6\pi) = -5.0 \cos(10t + 6\pi)$$
This is correct.
**Re-examining step 5:** The original position amplitude is 0.050, so velocity amplitude is 0.50, acceleration amplitude is 5.0.
Given the options, the only one with velocity near -0.50 and acceleration near -0.25 is (a), but acceleration magnitude is off.
**Possibility:** The problem might expect acceleration as $$a = -\omega^2 x$$, so:
$$a(0.10) = -10^2 \times x(0.10) = -100 \times 0.050 \cos(1 + 6\pi) = -5.0 \times 0.5403 = -2.70$$
This matches our previous calculation.
Therefore, the correct values are approximately:
$$v \approx -0.42$$
$$a \approx -2.70$$
None of the options exactly match, but closest velocity is negative near -0.5 and acceleration is negative and larger in magnitude.
**Final answer:** Velocity $$v \approx -0.42$$, acceleration $$a \approx -2.70$$ at $$t=0.10$$ s.
Velocity Acceleration 20991B
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