Consider an object moving along a line with the given velocity v . Assume t is time measured in seconds and velocities have units of \( \frac{\mathrm{m}}{\mathrm{s}} \) a. Determine when the motion is in the positive direction and when it is in the negative direction. b. Find the displacement over the given interval. c. Find the distance traveled over the given interval. \( v(\mathrm{t})=2 \mathrm{t}^{2}-16 \mathrm{t}+30 ;[0,6] \) a. When is the motion in the positive direction? Select the correct choice and, if necessary, fill in the answer box to complete your choice. A. The motion is in the positive direction for t -values in the interval(s) \( [0,3),(5,6] \). (Use a comma to separate answers as needed. Type your answers in interval notation.) B. The motion is never in the positive direction. When is the motion in the negative direction? Select the correct choice and, if necessary, fill in the answer box to complete your choice. A. The motion is in the negative direction for t -values in the interval(s) \( (3,5) \). (Use a comma to separate answers as needed. Type your answers in interval notation.) B. The motion is never in the negative direction. b. The displacement of the particle is 36 m . c. The total distance traveled by the particle is m .
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Bonus Knowledge
To determine when the motion is in the positive or negative direction, we first need to analyze the velocity function \( v(t) = 2t^2 - 16t + 30 \). To find the intervals of positive and negative motion, we set \( v(t) = 0 \) to find critical points. Solving \( 2t^2 - 16t + 30 = 0 \) using the quadratic formula: \[ t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} = \frac{16 \pm \sqrt{(-16)^2 - 4 \cdot 2 \cdot 30}}{2 \cdot 2} = \frac{16 \pm \sqrt{256 - 240}}{4} = \frac{16 \pm 4}{4} \] This gives us the critical points \( t = 5 \) and \( t = 3 \). Evaluating the sign of \( v(t) \) between the critical points: 1. For \( t \in [0, 3) \), pick \( t = 2 \): \( v(2) = 2(2)^2 - 16(2) + 30 = 8 - 32 + 30 = 6 \) (positive). 2. For \( t \in (3, 5) \), pick \( t = 4 \): \( v(4) = 2(4)^2 - 16(4) + 30 = 32 - 64 + 30 = -2 \) (negative). 3. For \( t \in (5, 6] \), pick \( t = 5.5 \): \( v(5.5) = 2(5.5)^2 - 16(5.5) + 30 = 60.5 - 88 + 30 = 2.5 \) (positive). Hence, the motion is in the positive direction for \( t \in [0, 3) \) and \( (5, 6] \) and in the negative direction for \( t \in (3, 5) \). b. To find the displacement over the interval \([0, 6]\), we integrate the velocity function: \[ \text{Displacement} = \int_0^6 v(t) \, dt = \int_0^6 (2t^2 - 16t + 30) \, dt. \] Calculating this integral gives us \( 36 \) meters, as stated. c. To find the total distance traveled, we need to consider the intervals where the velocity changes sign. The particle travels \( [0,3] \) (positive direction), then slows down from \( 3 \) to \( 5 \) (negative direction), and finally back to \( 6\) (positive direction). 1. Distance for \( [0, 3] \): \[ |v| \text{ gives distance }\int_0^3 (2t^2-16t+30) \, dt = 36 \,m. \] 2. Distance for \( [3, 5] \) (consider the absolute value of velocity): \[ \int_3^5 |v(t)| \, dt = \int_3^5 -(2t^2 - 16t + 30) \, dt = 12 \, m. \] 3. Distance for \( [5, 6] \): \[ \int_5^6 (2t^2 - 16t + 30) \, dt = 6 \, m. \] Thus, total distance traveled is \( 36 + 12 + 6 = 54 \, m. \)